Temporal variability of air-water gas exchange of carbon dioxide in clam and fish aquaculture ponds

The growing trend of land-based aquaculture has heightened the significance of comprehensively assessing air-water carbon dioxide (CO2) gas exchange in these inland waters, given their potential impact on carbon neutral strategies. However, temporal variations of partial pressure of CO2 (pCO2) and CO2 flux in clam and fish aquaculture ponds were barely investigated. We assessed the water surface pCO2 in one to five months intervals by deploying a lab-made buoy in three clam ponds and three fishponds located in tropical and subtropical climates. Measurements were conducted over a 24 h period each time, spanning from April 2021 to June 2022, covering the stocking, middle, and harvesting stages of the culture cycle. Diurnal pCO2 variations were dominantly controlled by biologically driven changes in dissolved inorganic carbon and total alkalinity (~97 %), while temperature and salinity effects were minor (~3 %). Clam ponds acted as a sink of atmospheric CO2 during stocking stages and transitioned to a source during middle to harvesting stages. In contrast, fishponds acted as a source of atmospheric CO2 throughout culture cycles and CO2 flux strengthened when reaching harvesting stages. Overall, clam ponds acted as a weak sink for atmospheric CO2 (-2.8 ± 17.3 mmol m-2 d-1), whereas fishponds acted as a source (16.8 ± 21.7 mmol m-2 d-1). CO2 emission was stronger during daytime coinciding with higher windspeeds compared to nighttime in fishponds. We suggest incorporating high temporal resolution measurements to account for diurnal and culture-stage variations, enabling more accurate estimates of air-water CO2 flux in aquaculture ponds. Moreover, the findings of this study highlight the importance of feeding, aeration, and biological activities (photosynthesis, remineralization, and calcification) in controlling the air-water CO2 flux in aquaculture ponds and such information can be used in implementing better strategies to achieve carbon neutral goals.

Ocean acidification increases inorganic carbon over organic carbon in shrimp's exoskeleton

Ocean acidification (OA) may either increase or have a neutral effect on the calcification in shrimp's exoskeleton. However, investigations on changes in the carbon composition of shrimp's exoskeletons under OA are lacking. We exposed juvenile Pacific white shrimps to target pHs of 8.0, 7.9, and 7.6 for 100 days to evaluate changes in carapace thickness, total carbon (TC), particulate organic carbon (POC), particulate inorganic carbon (PIC), calcium, and magnesium concentrations in their exoskeletons. The PIC: POC ratio of shrimp in pH 7.6 treatment was significantly higher by 175 % as compared to pH 8.0 treatment. Thickness and Ca% in pH 7.6 treatment were significantly higher as compared to pH 8.0 treatment (90 % and 65 %, respectively). This is the first direct evidence of an increased PIC: POC ratio in shrimp exoskeletons under OA. In the future, such changes in carbon composition may affect the shrimp population, ecosystem functions, and regional carbon cycle.

Radiocesium in the Taiwan Strait and the Kuroshio east of Taiwan from 2018 to 2019

The release of anthropogenic radiocesium to the North Pacific Ocean (NPO) has occurred in the past 60 years. Factors controlling ¹³⁷Cs (half-life, 30.2 year) and ¹³⁴Cs (half-life, 2.06 year) activity concentrations in the Kuroshio east of Taiwan and the Taiwan Strait (latitude 20° N–27° N, longitude 116° E–123° E) remain unclear. This study collected seawater samples throughout this region and analyzed ¹³⁴Cs and ¹³⁷Cs activity concentrations between 2018 and 2019. A principal component analysis (PCA) was performed to analyze the controlling factors of radiocesium. Results of all ¹³⁴Cs activity concentrations were below the detection limit (0.5 Bq m⁻³). Analyses of water column ¹³⁷Cs profiles revealed a primary concentration peak (2.1–2.2 Bq m⁻³) at a depth range of 200–400 m (potential density σ_θ: 25.3 to 26.1 kg m⁻³). The PCA result suggests that this primary peak was related to density layers in the water column. A secondary ¹³⁷Cs peak (1.90 Bq m⁻³) was observed in the near-surface waters (σ_θ = 18.8 to 21.4 kg m⁻³) and was possibly related to upwelling and river-to-sea mixing on the shelf. In the Taiwan Strait, ¹³⁷Cs activity concentrations in the near-surface waters were higher in the summer than in the winter. We suggest that upwelling facilitates the vertical transport of ¹³⁷Cs at the shelf break of the western NPO.

Functional Involvement of Thrombospondin in Platelet Aggregation Induced by Low Versus High Concentrations of Thrombin

Thrombospondin (TSP) is a major platelet secretory glycoprotein. Earlier studies of various investigators demonstrated that TSP is the endogenous platelet lectin and is responsible for the hemagglutinating activity expressed on formaldehyde-fixed thrombin-treated platelets. The direct effect of highly purified TSP on thrombin-induced platelet aggregation was studied. It was observed that aggregation of gel-filtered platelets induced by low concentrations of thrombin (≤0.05 U/ml) was progressively inhibited by increasing concentrations of exogenous TSP (≥60 μg/ml). However, inhibition of platelet aggregation by TSP was not observed when higher than 0.1 U/ml thrombin was used to activate platelets. To exclude the possibility that TSP inhibits platelet aggregation by affecting thrombin activation of platelets, three different approaches were utilized. First, by using a chromogenic substrate assay it was shown that TSP does not inhibit the proteolytic activity of thrombin. Second, thromboxane B2 synthesis by thrombin-stimulated platelets was not affected by exogenous TSP. Finally, electron microscopy of thrombin-induced platelet aggregates showed that platelets were activated by thrombin regardless of the presence or absence of exogenous TSP. The results indicate that high concentrations of exogenous TSP (≥60 μg/ml) directly interfere with interplatelet recognition among thrombin-activated platelets. This inhibitory effect of TSP can be neutralized by anti-TSP Fab. In addition, anti-TSP Fab directly inhibits platelet aggregation induced by a low (0.02 U/ml) but not by a high (0.1 U/ml) concentration of thrombin. In conclusion, our findings demonstrate that TSP is functionally important for platelet aggregation induced by low (≤0.05 U/ml) but not high (≥0.1 U/ml) concentrations of thrombin. High concentrations of exogenous TSP may univalently saturate all its platelet binding sites consequently interfering with TSP-crosslinking of thrombin-activated platelets.

Plasma Thrombospondin as an Indicator of Intravascular Platelet Activation in Patients with Vasculitis

The use of plasma thrombospondin (TSP) concentration was investigated as an indicator of intravascular platelet activation. Patients (n = 20) with diseases that have known vasculitis were included in the study. The range and the mean of plasma TSP concentrations of patients with vasculitis were 117 ng/ml to 6500 ng/ml and 791±1412 ng/ml (mean ± SD); the range and the mean of plasma TSP concentrations of control individuals (n = 33) were 13 ng/ml to 137 ng/ml and 59±29 ng/ml. When plasma TSP concentrations were correlated with plasma concentrations of another platelet activation marker, β-thromboglobulin (P-TG), it was found that the TSP concentration inei eased exponentially as the plasma β-TG level rose. A positive correlation between plasma levels of plasma TSP and serum fibrin degradation products was also observed. The results suggest that platelets are the primary source of plasma TSP in patients with various vasculitis and that plasma TSP can be a better indicator than β-TG to assess intravascular platelet activation due to its longer circulation half life.

Modeling RAS phenotype in colorectal cancer uncovers novel molecular traits of RAS dependency and improves prediction of response to targeted agents in patients

PURPOSE

KRAS wild-type status is an imperfect predictor of sensitivity to anti-EGF receptor (EGFR) monoclonal antibodies in colorectal cancer, motivating efforts to identify novel molecular aberrations driving RAS. This study aimed to build a quantitative readout of RAS pathway activity to (i) uncover molecular surrogates of RAS activity specific to colorectal cancer, (ii) improve the prediction of cetuximab response in patients, and (iii) suggest new treatment strategies.

EXPERIMENTAL DESIGN

A model of RAS pathway activity was trained in a large colorectal cancer dataset and validated in three independent colorectal cancer patient datasets. Novel molecular traits were inferred from The Cancer Genome Atlas colorectal cancer data. The ability of the RAS model to predict resistance to cetuximab was tested in mouse xenografts and three independent patient cohorts. Drug sensitivity correlations between our model and large cell line compendiums were performed.

RESULTS

The performance of the RAS model was remarkably robust across three validation datasets. (i) Our model confirmed the heterogeneity of the RAS phenotype in KRAS wild-type patients, and suggests novel molecular traits driving its phenotype (e.g., MED12 loss, FBXW7 mutation, MAP2K4 mutation). (ii) It improved the prediction of response and progression-free survival (HR, 2.0; P < 0.01) to cetuximab compared with KRAS mutation (xenograft and patient cohorts). (iii) Our model consistently predicted sensitivity to MAP-ERK kinase (MEK) inhibitors (P < 0.01) in two cell panel screens.

CONCLUSIONS

Modeling the RAS phenotype in colorectal cancer allows for the robust interrogation of RAS pathway activity across cell lines, xenografts, and patient cohorts. It demonstrates clinical utility in predicting response to anti-EGFR agents and MEK inhibitors.

A prospective randomized trial of prophylactic platelet transfusion and bleeding incidence in hematopoietic stem cell transplant recipients: 10,000/L versus 20,000/microL trigger

An optimal platelet-count threshold for prophylactic platelet transfusion in hematopoietic stem cell transplant (HSCT) recipients has yet to be determined. Between July 1997 and December 1999, we performed the first prospective randomized clinical trial addressing this issue in 159 HSCT recipients who received a prophylactic platelet transfusion when the morning platelet count fell below a 10,000/microL (10K) or 20,000/microL (20K) threshold. Subsequent prophylactic transfusions were administered according to a predetermined algorithm. The number of prophylactic and therapeutic transfusions and the incidence of minor and major bleeding were compared between the 2 groups. The groups were matched according to patient and transplantation characteristics. There were no significant differences in bleeding incidence or severity. Fourteen percent of patients in the 10K arm compared to 17% in the 20K arm had major bleeding events. Only 3 central nervous system bleeds occurred, 2 in the 10K group and 1 in the 20K group. No deaths were attributed to bleeding. An average of 11.4 days of bleeding occurred in both groups. An average of 10.4 platelet transfusions per patient were administered in the 10K group compared to 10.2 in the 20K group (P = .94). More transfusions were given above the assigned transfusion threshold in the 10K group than in the 20K group (4.3/patient versus 1.9/patient, respectively, P = .05). Safety measures incorporated into our study may have precluded demonstration of significant differences in platelet use between the groups. In conclusion, a platelet transfusion trigger of 10K was found to be safe; however, a decrease in platelet use was not achieved because of safety measures incorporated into our study design.

Suppression of interleukin-12 production through endogenously secreted interleukin-10 in activated dendritic cells: involvement of activation of extracellular signal-regulated protein kinase

Our recent study suggested the reverse relationship between the production of interleukin-10 (IL-10) and IL-12 in dendritic cells (DCs) activated by lipopolysaccharide (LPS) or LPS plus interferon (IFN)-gamma. In the present study, a series of experiments were performed to investigate the mechanisms responsible for this reverse relationship. Our results showed that neutralization of the secreted IL-10 by antibody could enhance the production of IL-12. Neutralization of IL-12 by antibody did not affect the IL-10 production. Addition of exogenous IL-10 suppressed the production of IL-12 by activated DCs, and addition of exogenous IL-12 did not affect IL-10 production. TaqMan real-time reverse transcriptase-polymerase chain reaction supported the fact that the observed effects occurred at mRNA transcription level. We also found that LPS or LPS plus IFN-gamma significantly enhanced the phosphorylation of extracellular signal-regulated protein kinase (ERK) and p38 mitogen-activated protein kinase. In addition, inhibition of ERK by PD98059 significantly suppressed IL-10 and increased the IL-12 production. Exogenous IL-10 reversed the upregulated production of IL-12 induced by PD98059. The above findings suggest a unidirectional negative autocrine regulation of IL-12 by IL-10 in activated DCs and that activation of ERK involves the differential production of IL-10 and IL-12 by activated DCs. Thus, the regulation of differential production of IL-10 and IL-12 may play an important role for DCs in priming T helper 1 (Th1) or Th2 in the immune responses.

Monocyte-derived CD1a+ dendritic cells generated in two different culture systems: immunophenotypic and functional comparison

Previous studies demonstrated that CD1a+ dendritic cells (DCs) could not be prepared ex vivo without using fetal calf serum (FCS). Recently, we developed a method of using heparin to induce differentiation of human monocytes into CD1a+ DCs without using FCS. In order to determine the potential clinical applicability of heparin-induced CD1a+ DCs, we conducted this study to compare both types of CD1a+ DCs, immunophenotypically and functionally. Our results showed that the expression of CD1a on heparin-DCs was lower than that on FCS-DCs. Both types of DCs expressed similar levels of CD11c, HLA-DR, CD40, CD83, CD80 and CD86 before and after lipopolysaccharide stimulation. Immature heparin-DCs and FCS-DCs had similar phagocytic activities. Heparin-DCs consistently secreted higher interleukin-10 (IL-10) and lesser IL-12 than FCS-DCs after activation. Mature heparin-DCs were slightly more active than mature FCS-DCs in stimulating the proliferation of allogeneic CD4+ T cells. Both types of mature CD1a+ DCs primed the naïve CD4+ T cells to produce large amount of interferon-gamma (IFN-gamma). However, naïve CD4+ T cells stimulated with FCS-DCs produced more IFN-gamma, while the naïve CD4+ T cells stimulated with heparin-DCs produced more IL-5. The results indicate that both types of CD1a+ DCs do not have identical function in the priming of CD4+ T cells and have minor difference in immunophenotypes.

Obtaining blood samples for anti-factor Xa quantification through umbilical artery catheters

OBJECTIVE

Neonates who are treated with low-molecular-weight heparin require repeated venipunctures to monitor anti-factor Xa (anti-FXa) levels. Generally, blood withdrawn from umbilical artery catheters (UACs) is not useful for such monitoring because heparin in the fluids running through the catheters contaminates the results. We tested methods for collecting blood for anti-FXa levels from UACs through which heparin-containing fluids were running, in an attempt to reduce the need for repeated venipunctures of anticoagulated neonates.

STUDY DESIGN AND METHODS

A new blood drawing port, through which no heparin was run, was added to the UAC system. Qualifying neonates with UACs were randomized to have anti-FXa levels drawn after line-clearing volumes of 0.5, 3.0, or 4.0 ml.

RESULTS

Twelve patients with UACs were enrolled and all completed the study with no adverse events. When 0.5, 3.0, or 4.0 ml of blood was cleared from the UAC before withdrawing the test sample, heparin contaminated the test (anti-FXa levels > or = 0.1 U/ml) in 66%, 16%, and 8% of samples, respectively. Differences between the 0.5- vs. 3.0-ml line-clearing volumes and between the 0.5- vs. 4.0-ml clearing volumes were significant (p = 0.0026 and 0.0006, respectively).

CONCLUSION

Blood samples for anti-FXa can be drawn from UACs through which heparin-containing solutions are infusing if a port is added through which no heparin-containing fluids are run, a line-clearing volume of at least 4.0 ml is drawn, and a contamination rate of 8% of samples is acceptable.

The autoimmune regulator (AIRE) is a DNA-binding protein

The autoimmune regulator (AIRE) protein is a putative transcription regulator with two plant homeodomain-type zinc fingers, a putative DNA-binding domain (SAND), and four nuclear receptor binding LXXLL motifs. We have shown here that in vitro, recombinant AIRE can form homodimers and homotetramers that were also detected in thymic protein extracts. Recombinant AIRE also oligomerizes spontaneously upon phosphorylation by cAMP dependent protein kinase A or protein kinase C. Similarly, thymic AIRE protein is phosphorylated at the tyrosine and serine/threonine residues. AIRE dimers and tetramers, but not the monomers, can bind to G-doublets with the ATTGGTTA motif and the TTATTA-box. Competition assays revealed that sequences with one TTATTA motif and two tandem repeats of ATTGGTTA had the highest binding affinity. These findings demonstrate that AIRE is an important DNA binding molecule involved in immune regulation.

Characterization of immunologic tolerance induced by transfusion of UV-B--irradiated allogeneic mononuclear leukocytes

Transfusions of UV-B--irradiated peripheral blood mononuclear cells (UV-B--PBMCs) from BALB/c (H-2(d)) mice into CBA (H-2(k)) mice can induce humoral immune tolerance to H-2(d) antigens, and the induced tolerance is partially mediated by negative regulatory PBMCs. To further identify which subset of spleen mononuclear leukocytes (MNLs) in the tolerant CBA mice is responsible for the negative regulatory activity, adoptive transfer experiments were conducted using spleen MNLs from the tolerant CBA mice. Results showed that only CD4(+) T cells could transfer the negative regulatory activity in a dose-dependent manner. This negative regulatory activity was significantly reduced when CD25(+) helper T cells were removed. Further study suggested that inhibition of IL-12 production by UV-B--irradiated PBMCs played a role in the induction of immune tolerance. In vitro study of the cytokine production profile by CBA CD4(+) T cells, after stimulation with gamma-irradiated BALB/c spleen cells, revealed an enhanced production of the type 2 T-cell cytokines after tolerance induction. Induction of tolerance also prevented the development of cytotoxic T cells in CBA mice against BALB/c MNLs. Adoptive transfer study suggested that the cellular immune tolerance was also mediated by CD4(+) negative regulatory T cells. The induced immune tolerance was nullified after 400 cGy sublethal gamma irradiation. These results suggest that the ex vivo study of cytokine production by T cells may be used to monitor tolerance induction and the selection of gamma radiation dose is critical for potential clinical application of the tolerance induced by UV-B--PBMCs. (Blood. 2001;98:1239-1245)

Structural studies of a neuropeptide precursor protein with an RGD proteolytic site

The snail Lymnaea stagnalis produces a neuropeptide precursor protein that contains seven Arg-Gly-Asp (RGD) sites. These sites are recognized and cleaved by one or more prohormone convertases in the first processing step to yield mature neuropeptides in the secretory pathway. Conformations of two synthetic RGD-containing peptides derived from the L. stagnalis precursor protein were determined by NMR spectroscopy. The peptides were tested in a platelet aggregation assay for RGD activity and were processed in vitro by PC2 and furin. The native peptide with a proline following the RGD site has minimal structure around the RGD region, does not inhibit platelet aggregation, and is properly processed by the enzymes PC2 and furin. A variant of the native fragment with a serine following the RGD sequence has a significant amount of a reverse turn around the RGD region, is a potent inhibitor of platelet aggregation, and is processed with the same specificity as the native fragment. The large conformational differences between the two peptides provide a molecular mechanism for effects of proline residues following the RGD site and suggest that precursor processing is influenced more by flexibility than by the conformation of the processing site.

Platelet transfusions in the neonatal intensive care unit:factors predicting which patients will require multiple transfusions

BACKGROUND

Previous studies suggest that recombinant thrombopoietin (rTPO) will increase platelet production in thrombocytopenic neonates. However, the target populations of neonates most likely to benefit should be defined. Studies suggest that rTPO will not elevate the platelet count until 5 days after the start of treatment. Therefore, the neonates who might benefit from rTPO are those who will require multiple platelet transfusions for more than 5 days. This study was designed to find means of prospectively identifying these patients.

STUDY DESIGN AND METHODS

A historic cohort study of all patients in the neonatal intensive care unit (NICU) at the University of Florida who received platelet transfusions from January 1, 1997, through December 31, 1998, was conducted.

RESULTS

Of the 1389 patients admitted to the NICU during the study period, 131 (9.4%) received platelet transfusions. Seventeen were treated with extracorporeal membrane oxygenation and were excluded from further analysis. Of the remaining 114 patients, 55 (48%) received one transfusion and 59 (52%) received more than one transfusion (21 had >4). None of the demographic factors examined predicted multiple platelet transfusions. However, two clinical conditions did; liver disease and renal insufficiency. Neonates who received one platelet transfusion had a relative risk of death 10.4 times that in neonates who received none (p = 0.0001). Neonates who received >4 platelet transfusions had a risk of death 29.9 times that in those who received no transfusions (p = 0.0001).

CONCLUSION

NICU patients with liver disease or renal insufficiency who receive one platelet transfusion are likely to receive additional transfusions. Therefore, these patients constitute a possible study population for a Phase I/II rTPO trial.

Mechanisms for genetically predetermined differential quantitative expression of HLA-A and -B antigens

Previous studies showed that different HLA-A and -B antigens are differentially expressed in cells. Their relative quantities are genetically predetermined and inherited according to Mendelian laws. To investigate mechanisms responsible for this differential expression, a correlation study between the relative quantities of different HLA-A and -B proteins and their mRNA levels in eight different HLA-phenotyped lymphoblastoid cell lines (LCLs) were performed. The results show proportional correlation in all the studied cell lines except those that are positive for HLA-A24. Study of the turnover of HLA antigens reveals that different HLA-A and -B antigens are proportionally degraded. Measurement of the relative quantities of HLA-A and -B mRNAs in six LCLs before and after treatment with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), an inhibitor of RNA polymerase II, demonstrates that HLA-A and -B mRNAs are proportionally degraded except slight differences in two LCLs. Measurement of the relative quantities of different HLA-A and -B pre-mRNAs in nuclei shows that they are not proportional to the relative quantities of their respective mature mRNAs in cytoplasm in four of six LCLs. These results indicate that combinations of different regulatory steps which include gene transcription, pre-mRNA splicing and mRNA degradation are involved in the genetically predetermined quantitative differential expression of HLA-A and -B antigens. Transcription of HLA genes and splicing of HLA pre-mRNAs appear to be the dominant regulatory steps.

Management of a patient with a mechanical aortic valve and antibodies to both thrombin and factor V after repeat exposure to fibrin sealant

We describe a patient who developed a markedly prolonged PT, PTT, and thrombin time 13 days after repeat exposure to fibrin sealant during coronary artery bypass grafting and aortic valve replacement. Evaluation revealed an inhibitor to bovine thrombin that cross-reacted with human thrombin. In addition an inhibitor to human coagulation factor V was identified. Despite coagulation abnormalities there was no evidence of bleeding. Nevertheless, effective anticoagulation was required to minimize the thrombotic complications associated with the patient's prosthetic valve. We elected to take a conservative approach and not utilize pharmacologic anticoagulation until there was diminution in the effect of the acquired inhibitors. We report on our patient's course and review the available literature addressing the management of patients demonstrating inhibitors to blood coagulation factors after repeat exposure to fibrin sealants.

Measurement of tissue factor activity in whole blood

High circulating levels of the procoagulant molecule tissue factor (TF) are associated with thrombosis in a variety of diseases including unstable angina, cancer, and sepsis. Currently, there are no clinical assays to measure the level of TF activity in whole blood. We present an assay called Tissue Factor Clotting Time ("TiFaCT") that detects fibrin formation in human blood. The mean baseline clotting time in a healthy population was 472 +/- 94 s (mean +/- SD, n = 150). Bacterial lipopolysaccharide (LPS or endotoxin) shortened the clotting time in a time-dependent manner. Inhibitory anti-TF antibodies prolonged the clotting time of LPS-stimulated blood, indicating that the shortened clotting time was due to induction of TF expression. Patients with unstable angina had shortened mean baseline clotting time (284 +/- 86, n = 13) compared with healthy volunteers (474 +/- 98, n = 30), suggesting that these patients had elevated levels of circulating TF. The TiFaCT assay should prove clinically useful in quantifying the levels of circulating TF in patients at risk of thrombosis.

Prevention of graft-versus-host disease by induction of immune tolerance with ultraviolet B-irradiated leukocytes in H-2 disparate bone marrow donor

Transfusions (Tx) of Ultraviolet B (UVB)-irradiated peripheral blood mononuclear leukocytes (MNL) have been shown to induce humoral immune tolerance to major histocompatability complex (MHC) antigens (Blood 88:4375, 1996). To determine whether cellular immune tolerance to MHC antigens can be induced by the same approach, transplantation of bone marrow and spleen cells from tolerant donors across the H-2 barrier was conducted to study its effect on prevention of graft-versus-host disease (GVHD). After immune tolerance induction by four weekly Tx of UVB-irradiated BALB/c (H-2(d)) peripheral blood MNL into CBA/HT6 (H-2(k)) mice, bone marrow cells (BMC) and spleen MNL from tolerant or naive CBA mice were transplanted into lethally irradiated BALB/c mice. The transplanted mice were followed by measuring body weight, peripheral leukocyte counts, GVHD, survival, and cytokine response. All BALB/c recipient mice were fully engrafted with H-2(k) CBA donor cells after transplantation. The severity of GVHD was significantly attenuated in BALB/c mice transplanted with BMC and spleen MNL from tolerant CBA donor mice. The recovery of peripheral leukocyte and lymphocyte counts were faster and more complete in mice transplanted with cells from the tolerant donors. The serum cytokine profile after transplantation with tolerant donor cells showed increased interleukin-4 and reduced gamma interferon that are consistent with a polarized Th2 response. The results pooled from three separate experiments showed that BALB/c mice transplanted with 5 x 10(6) BMC and 4 x 10(5) spleen MNL from tolerant CBA donors had better overall survival than the control group (72% v 17%, P =.018). The findings show that transplantation with bone marrow and spleen cells from tolerant H-2 disparate donor mice is associated with significant attenuation of GVHD and better outcomes. The results also support that transfusions of UVB-irradiated leukocytes may induce cellular immune tolerance.

Role of class-II major histocompatibility complex (MHC)-antigen-positive donor leukocytes in transfusion-induced alloimmunization to donor class-I MHC antigens

It has been shown that peripheral-blood mononuclear leukocytes (MNL) are responsible for transfusion-induced alloimmunization to donor major histocompatability complex (MHC) antigens. However, it is not known which subset of MNL is responsible for this immune response. Because elimination of class-II MHC antigen-positive passenger leukocytes effectively prolongs the survival of allografts, it has been hypothesized that class-II positive MNL are responsible for immunizing transfusion recipients to donor MHC antigens. To test this hypothesis, two different approaches were used. First, we compared the alloantigenicity of BALB/c mice (H-2(d)) peripheral blood MNL before and after depletion of class-II positive cells. CBA mice (H-2(k)) were used as transfusion recipients. Antibody development to donor class-I H-2 antigens was determined by flow cytometry and enzyme-linked immunoassay. After four weekly transfusions of MNL depleted for class-II positive cells, only 25% of recipient mice developed antibodies to donor H-2(d) antigens. In contrast, all mice transfused with control MNL became immunized. Second, we studied the alloantigenicity of peripheral MNL from C57BL/6 mice (H-2(b)) with homozygous deficiency of class-II MHC molecules in H-2 disparate recipient mice. After transfusions with class-II MHC molecule-deficient MNL, 0% of BALB/c, 40% of C57BR, and 25% of CBA-recipient mice developed antibodies to donor H-2(b) antigen. All control recipient mice were immunized. The antibody activities of the controls were also higher than those in the treatment group who became immunized. Thus, our study shows that class-II MHC antigen-positive MNL play a significant role in transfusion-induced alloimmunization to donor class-I MHC antigens. The results also support the hypothesis that direct antigen presentation by donor class-II positive MNL to the immune system of transfusion recipients is critical for the initiation of humoral immune response to donor MHC antigens.

The Collaborative Hospital Transfusion Study: variations in use of autologous blood account for hospital differences in red cell use during primary hip and knee surgery

BACKGROUND

Red cell use in patients undergoing Diagnosis Related Group (DRG) 209 procedures (major joint and limb reconstruction procedures of the lower extremities) has been shown to have large, unexplained interhospital variations.

STUDY DESIGN AND METHODS

Abstracted records of 2590 consecutive DRG 209 patients at five university hospitals from January 1992 to December 1993 were stratified by procedure and preoperative blood deposit status. Patient characteristics and transfusion and in-hospital outcomes were compared across hospitals.

RESULTS

Blood use among patients who did not preoperatively deposit blood was similar across hospitals. Significant differences were found across hospitals for total hip replacement patients in the percentage of patients preoperatively depositing blood (59-80%), percentage of patients receiving transfusion(s) (51 to > 99%), the mean number of units collected per patient (1.6-2.9), and the mean number of unused autologous units per 100 patients (1-185). No significant differences were found in the percentage of those who deposited blood and then required allogeneic units. There was little variability in length of hospital stay or in last hematocrits. Findings were similar for total knee replacement patients.

CONCLUSIONS

Interhospital variations in red cell use for primary total hip and knee reconstruction are primarily due to hospital-specific differences in autologous blood collection and transfusion.

Neonatal alloimmune thrombocytopenia associated with maternal anti-HLA antibody: a case report

PURPOSE

Although neonatal alloimmune thrombocytopenia (NAIT) due to maternal sensitization to human platelet antigens is well described, the role of maternal anti-human lymphocyte antigen (HLA) antibodies in NAIT is not yet firmly established.

PATIENT

A 31-week-old girl born prematurely to a G2POA1 mother was noted to have thrombocytopenia which lasted 18 days without any evidence of infection.

MATERIALS AND METHODS

Platelet-associated IgG, anti-platelet antibody, and platelet PL(A1) antigen typing were determined using a commercial solid-phase red cell adherent test. Antibodies to platelet glycoproteins human platelet antigen (HPA) 1 to 5 were determined using a commercial ELISA. Anti-HLA antibodies were assayed using a standard lymphocytotoxicity test. Activities and IgG subclass of anti-HLA antibodies in plasma of the mother and other postpartum mothers were measured using purified HLA antigens in an enzyme linked immunoassay.

RESULTS

Both mother and infant were positive for HPA-1 (PL(A1)) antigens. The mother's HLA phenotype was A3, A31, B7, B27. The level of platelet-associated IgG was not increased on maternal platelets; however, increased platelet-associated IgG was detected on the infant's platelets. Antibodies to platelet glycoproteins HPA1 to 5 were not detectable in the maternal plasma. Maternal serum was positive for anti-HLA antibodies, which reacted to 23 of 27 panel cells. The presence of HLA antibodies was confirmed by enzyme-linked immunoassay. Of note, the maternal antibodies reacted positively to the infant's platelets and anti-IgG anti-HLA antibodies were detected in the serum sample from the infant collected at birth. When the activity and IgG subclass of the maternal anti-HLA antibodies were compared with those of other mothers known to have high anti-HLA antibody activity, no differences were noted.

CONCLUSION

This report documents a patient with neonatal thrombocytopenia induced by maternal IgG anti-HLA antibody. Neither activity nor IgG subclass could explain the occurrence of NAIT. The factors that contribute to NAIT induced by maternal anti-HLA antibodies remain to be identified.

The specific hospital significantly affects red cell and component transfusion practice in coronary artery bypass graft surgery: a study of five hospitals

BACKGROUND

Interhospital differences in blood transfusion practice during coronary artery bypass graft (CABG) surgery have been noted, but the underlying issues have not been identified.

STUDY DESIGN AND METHODS

Records of 3217 consecutive CABG cases in five university teaching hospitals in 1992 and 1993 were stratified by hospital, type of revascularization conduit, patients' sex, and other factors. Statistical methods were used to compare patient characteristics, transfusion outcomes, and hospital outcomes.

RESULTS

Forward two-step logistic regression using patient likelihood of red cell transfusion factors in the first step and the specific hospital in the second step revealed a significant effect of hospital on the delta odds ratios for red cell transfusion. This finding was confirmed by analyses of a highly stratified subset of cases, males in diagnosis-related group 107 (primary cases of coronary bypass without coronary catheterization) who underwent revascularization with venous and internal mammary artery grafts, revealing variations among hospitals from 109 to 457 units of red cells transfused per hundred cases. Corresponding variations in transfusions of all blood components were from 324 to 1019 units by hospital. Variation in red cell transfusion practice among surgeons in the same hospital was not responsible for these interhospital differences.

CONCLUSION

The effect of the specific hospital on transfusion practice is attributed to institutional differences that, through reasons of training or hierarchy, become ingrained in hospitals.

In vitro-generation of islets in long-term cultures of pluripotent stem cells from adult mouse pancreas

Pancreatic islets of Langerhans exhibit an architecture and cellular organization ideal for rapid, yet finely controlled, responses to changes in blood glucose levels. In type I, insulin-dependent diabetes (IDD), this organization is lost as a result of the progressive autoimmune response which selectively destroys the insulin-producing pancreatic beta cells. Since beta cells are perceived as end-stage differentiated cells having limited capacity for regeneration in situ, individuals with IDD resulting from beta cell loss or dysfunction require life-long insulin therapy. Efforts to produce islet neogenesis or initiate islet growth in vitro from either fetal or adult tissue have had minimal success. We now report that pancreatic-derived, pluripotent islet-producing stem cells (IPSCs), isolated from prediabetic mice, can be grown in long-term cultures and differentiated into immature functional islet-like structures containing cells which express low levels of insulin, glucagon and/or somatostatin. When such in vitro grown islets were implanted into clinically diabetic NOD mice, the implanted mice were successfully weaned from insulin long-term (>50 days) without ill effects. The implanted mice maintained blood glucose levels just above euglycemic (180-220 mg/dl) and showed no signs of disease. Thus, this technical breakthrough provides new therapeutic approaches to diabetes as an alternative to insulin therapy.

Measurement of relative quantities of different HLA-A and -B mRNAs in cells by reverse transcription-polymerase chain reaction and denaturing gradient gel electrophoresis

In order to determine the relative quantities of different HLA-A and -B mRNAs in cells, we have developed a simple and reliable method by using reverse transcription-polymerase chain reaction (RT-PCR), denaturing gradient gel electrophoresis (DGGE) and phosphor imaging analysis. Cytoplasmic RNA from lymphoblastoid cell lines with well-characterized HLA phenotypes are reversely transcribed with a primer specific for all HLA-A and -B antigens. The first-strand cDNA is used as template for quantitative PCR. The primer pair used for quantitative PCR are specific for all class I HLA and one of the primers is labeled with [gamma-32P]ATP. The amplified sequences include parts of exon 2 and exon 3 which contain most polymorphic residues in class I HLA molecules. The RT-PCR products containing the amplified HLA-A and -B sequences are separated by DGGE. The radioactivities of different DNA bands separated in denaturing gradient polyacrylamide gels are measured by phosphor imaging and used to determine the relative amounts of HLA-A and -B mRNAs. This approach is validated by using samples containing known quantities of different HLA-A and -B mRNA transcripts and confirmed by S1 nuclease protection assay. The combined RT-PCR/DGGE approach therefore provides a simple and reliable method for quantitation of relative amounts of different HLA-A and -B mRNAs in cells. This method should also be useful for studying the expression of other highly conserved and duplicated genes.

Antiphospholipid antibodies in pediatric lupus nephritis

Antiphospholipid antibodies (aPL) of various isotypes are known to occur in systemic lupus erythematosus (SLE), but the significance of this finding in the pediatric population remains unclear. Our aim was to determine whether children with lupus nephritis have an increased risk of thrombosis and whether antiphosphatidylserine (APS) or antiphosphatidylinositol (API) antibodies were predictive of thrombotic complications. Thirty-six children (27 girls/9 boys; 44% black) with SLE nephritis (WHO II, 1; WHO III, 7; WHO IV, 21; WHO V, 7) were evaluated for antiphosphatidylserine, antiphosphatidylinositol, and anticardiolipin immunoglobulin (Ig) G and IgM isotypes, using a modified solid-phase enzyme-linked immunoassay (ELISA). Twenty-four patients (67%) had at least one positive aPL. Longitudinal data on 26 patients showed fluctuations in the degree of positivity. Eight patients experienced thrombotic complications, with equal distribution between arterial and venous events. Other clinical manifestations included thrombocytopenia in seven patients (19%), hemolytic anemia (44%), lupus anticoagulant (6%) and false-positive Venereal Disease Research Laboratory (VDRL) test results (11%). Comparisons between those with and without a thrombotic event showed no detectable difference in the incidence of aPL positivity between the two groups. We conclude that neither APS, API, nor anticardiolipin (ACL) activity was predictive of thrombotic complications in our subset of patients with lupus nephritis.

Induction of humoral immune tolerance to major histocompatibility complex antigens by transfusions of UVB-irradiated leukocytes

To determine whether immune tolerance to donor major histocompatibility complex (MHC) antigens can be induced by transfusions of UVB-irradiated leukocytes, studies were conducted in inbred strains of mice with well-characterized MHC antigens. CBA mice with H-2k phenotype and BALB/c mice with H-2d phenotype were used as recipients and donors, respectively. Humoral immune tolerance is defined as absence of antibody response after challenge with transfusions of untreated donor leukocytes. It was found that transfusions of purified peripheral blood mononuclear leukocytes irradiated with 1,200 mJ/cm2 UVB not only prevented allo-immunization but also induced humoral immune tolerance to donor class-I and -II MHC antigens in all recipient mice. Donor plasma and platelets interfered with the induction of this tolerance. The tolerance induction by UVB-irradiated leukocytes is dose-dependent. Four weekly transfusions of 2 x 10(5) leukocytes were required to ensure tolerance induction in all mice. The results of a long-term follow-up study showed that the induced tolerance is long-lasting and can withstand repeated challenges by untreated donor leukocytes. Recipient mice tolerant to H-2d antigens also became tolerant to H-2b, H-2r, and H-2n MHC antigens but did not have impaired antibody responses to antigens unrelated to donor leukocytes. Adoptive transfer experiments showed the development of negative regulatory cells in spleens of the tolerized mice. In view of recent feasibility of using UVB-irradiated human platelet concentrates for prevention of HLA alloimmunization, the findings of this study support that UVB-irradiated donor leukocytes could have potential, important clinical application in transplantation medicine.

High frequency of HLA-A*0207 subtype in Chinese population

BACKGROUND

HLA-A2 is the most polymorphic and most common HLA phenotype found in various ethnic populations. Seventeen HLA-A2 subtypes have been reported and characterized by molecular techniques. Differences among these subtypes are limited to a few amino acids. Among them, HLA-A*0201 is the predominant subtype among whites. The results of a recent study, however, suggest that the HLA-A*0207 subtype may be present at a high frequency in the Chinese population.

STUDY DESIGN AND METHODS

To determine the exact frequency of the HLA-A*0207 subtype in the Chinese population, genomic DNA samples obtained from 54 HLA-A2-positive Chinese in Taiwan were studied by using sequence-specific primers and polymerase chain reaction.

RESULTS

HLA-A*0207 was present in 56 percent of the studied subjects. The estimated gene frequency for HLA-A*0207 is 17.8 percent in the Chinese population.

CONCLUSION

HLA-A*0207 is the most common HLA-A2 subtype among Chinese. The high frequency of the HLA-A*0207 allele in this population offers a unique opportunity to study the ways in which different HLA-A2 subtypes may influence the clinical outcome of allograft transplantation and the disease susceptibility of recipients.

Determinants of red cell, platelet, plasma, and cryoprecipitate transfusions during coronary artery bypass graft surgery: the Collaborative Hospital Transfusion Study

BACKGROUND

Very little is known about the determinants of blood transfusions in patients undergoing coronary artery bypass graft surgery.

STUDY DESIGN AND METHODS

To identify factors that influenced the transfusion of red cells, platelets, plasma, and cryoprecipitate, statistical methods were used to study 2476 consecutive diagnosis-related group 106 and 107 patients in five teaching hospitals who underwent coronary artery bypass surgery between January 1, 1992, and June 30, 1993.

RESULTS

The likelihood of red cell transfusion was significantly associated with 10 preoperative factors: 1) admission hematocrit, 2) the patient's age, 3) the patient's gender, 4) previous coronary artery bypass surgery, 5) active tobacco use, 6) catheterization during the same admission, 7) coagulation defects, 8) insulin-dependent diabetes with renal or circulatory manifestations, 9) first treatment of new episode of transmural myocardial infarction, and 10) severe clinical complications. Platelet and/or plasma transfusions were strongly associated with the dose of red cells transfused. Transfusion requirements and other in-hospital outcomes were associated with patient characteristics, surgical procedure (reoperation vs. primary procedure), and the conduits used for revascularization (venous graft only, venous and internal mammary artery graft, or internal mammary artery graft only). Blood resource use and donor exposures were evaluated with respect to the risk to patients of contracting hepatitis C virus and human immunodeficiency virus infections.

CONCLUSION

The classification of coronary artery bypass graft patients on the basis of attributes known preoperatively and by conduits used yields subsets of patients with distinctly different transfusion requirements and in-hospital outcomes.

Functional significance of varied quantitative and qualitative expression of HLA-A2.1 antigens in determining the susceptibility of cells to cytotoxic T lymphocytes

To determine whether varied quantitative HLA expression affects the susceptibility of target cells to CTLs, a panel of 15 EBV-transformed lymphoblastoid cell lines expressing a fivefold difference of surface HLA-A2.1 antigens were employed. The susceptibility of these cell lines to HLA-A2.1-restricted and influenza virus matrix peptide-specific CTLs was correlated with the amounts of HLA-A2.1 antigens expressed on their surface. The results show a linear correlation between both parameters using exogenous viral peptide. The same linear correlation was observed when target cells infected with influenza virus were studied. These findings support the hypothesis that the amount of HLA antigens expressed on the cell surface is functionally significant in determining the susceptibility of target cells to CTLs. During our study, we also found that two HLA-A-2.1-positive cell lines were unresponsive to the CTL. Further investigation of the amino acid sequences of these cell lines reveals that their HLA-A2.1 antigens belong to the HLA-A0207 subtype which is different from HLA-A0201(A2.1) by one nucleotide. This difference results in an amino acid substitution from tyrosine to cysteine at position 99 of HLA-A2.1 heavy chains. Using a peptide-induced reconstitution assay, it was shown that failure of the peptide binding is responsible for the absence of cytotoxicity. This finding supports the hypothesis that amino acid 99 plays an important role in determining the peptide-binding specificity of HLA-A2 molecules.

The role of HLA antibodies in neonatal thrombocytopenia: a prospective study

The role of HLA antibodies in neonatal alloimmune thrombocytopenia is controversial. We prospectively studied the sera of obstetric patients at delivery for HLA antibodies and correlated their presence with umbilical cord blood platelet counts. We studied 493 births at The Johns Hopkins Hospital comprising of 357 African American, 115 Caucasian, and 21 babies of other racial groups. One hundred and thirty nine mothers had HLA antibodies. Of these HLA alloimmunized mothers, only ten infants had platelet counts of 150,000/ microL or less. Three hundred and eight mothers with no detectable antibodies gave birth to 27 infants with platelet counts of 150,000/microL or less. Yates corrected Chi square analysis showed no significant relationship between maternal HLA alloimmunization and baby platelet count (p = 0.709). Only 8 of sixty cord sera from babies of HLA alloimmunized mothers were positive for HLA antibodies. The HLA cord blood antibody results were then correlated with the neonatal platelet counts. The Fisher's exact test showed no significant relationship between the presence of HLA antibodies in cord blood samples and neonatal platelet counts (p = 0.232). Although one third (31%) of mothers have HLA antibodies, neonatal thrombocytopenia is rarely associated with this finding. However, HLA antibodies can cross the placenta, and in these unusual cases, may be associated with a higher risk of neonatal thrombocytopenia.

IgM rheumatoid factors react with human class I HLA molecules

Half of 30 human polyclonal IgM rheumatoid factors (RF) showed positive ELISA reactions with affinity-isolated human class I molecules (A2 and B7). Positive RF reactivity with isolated class I heavy chains indicated that anti-class I RF interaction did not merely reflect RF anti-beta 2m specificity. Cross-reactions between antigenic determinants on human IgG, class I molecules, and beta 2m reacting with RF could be demonstrated by ELISA inhibition. When gene products of A2 alpha 2 exons 2, 3, and 4 were synthesized as overlapping heptamers on polypropylene pins, six RF-reactive epitopes within solvent accessible class I HLA regions were identified: EPRAPWI, QEGPEYW, QTHRVDL (second A2 exon), EQLRAYL, GTCVEWL, and WLRRYLE (third A2 exon). Glycine-alanine substitution for each residue within these RF-reactive sites identified R48, W51, E55, Y107, R108, W147, Q155, and E172 as immunodominant residues for RF reactivity. Many of these RF-reactive class I regions also showed positive ELISA reactions with monoclonal human IgM RFs derived from rheumatoid arthritis synovial B cells. Whole serum from patients with rheumatoid arthritis showed a spectrum of IgM, IgA, and IgG Abs that adsorbed to and could be eluted from monomeric IgG or HLA A2 affinity columns. Normal serum similarly analyzed showed only trace reactions with IgG, A2, or beta 2m. Flow cytometry using RF incubated with A2 cell lines showed definite immunofluorescence reactivity with cell membranes not observed with normal non-RF IgM. Reactivity of human IgM RF with determinants on class I molecules may reflect antigenic overlap within several members of Ig gene superfamily products.

IgM rheumatoid factors react with human class I HLA molecules

Half of 30 human polyclonal IgM rheumatoid factors (RF) showed positive ELISA reactions with affinity-isolated human class I molecules (A2 and B7). Positive RF reactivity with isolated class I heavy chains indicated that anti-class I RF interaction did not merely reflect RF anti-beta 2m specificity. Cross-reactions between antigenic determinants on human IgG, class I molecules, and beta 2m reacting with RF could be demonstrated by ELISA inhibition. When gene products of A2 alpha 2 exons 2, 3, and 4 were synthesized as overlapping heptamers on polypropylene pins, six RF-reactive epitopes within solvent accessible class I HLA regions were identified: EPRAPWI, QEGPEYW, QTHRVDL (second A2 exon), EQLRAYL, GTCVEWL, and WLRRYLE (third A2 exon). Glycine-alanine substitution for each residue within these RF-reactive sites identified R48, W51, E55, Y107, R108, W147, Q155, and E172 as immunodominant residues for RF reactivity. Many of these RF-reactive class I regions also showed positive ELISA reactions with monoclonal human IgM RFs derived from rheumatoid arthritis synovial B cells. Whole serum from patients with rheumatoid arthritis showed a spectrum of IgM, IgA, and IgG Abs that adsorbed to and could be eluted from monomeric IgG or HLA A2 affinity columns. Normal serum similarly analyzed showed only trace reactions with IgG, A2, or beta 2m. Flow cytometry using RF incubated with A2 cell lines showed definite immunofluorescence reactivity with cell membranes not observed with normal non-RF IgM. Reactivity of human IgM RF with determinants on class I molecules may reflect antigenic overlap within several members of Ig gene superfamily products.

Use of thrombospondin level to predict the clinical course of atopic dermatitis associated with food hypersensitivity or skin infection

Plasma thrombospondin (TSP) levels were monitored in patients with atopic dermatitis (AD) exacerbated by food hypersensitivity (FH) or skin infection. In both groups, the TSP levels correlated positively with skin disease severity score from the onset to 2 months after treatment. A sustained TSP level above 250 ng/ml predicted a 7-fold increase in the incidence of flare-up of AD.

A combined approach for quantitation of each specific HLA-A or -B antigen expressed on cells

In order to measure the amount of each individual HLA-A or -B antigen expressed in or on a cell without relying on monoclonal antibodies to different specific HLA antigens, we have developed a combined approach that consists of two separate measurements. The first measurement is to determine the relative quantities of different HLA-A and -B antigens in lysates of whole cells using IEF gel electrophoresis, immunoblotting with 171.4 anti-HLA heavy chain monoclonal antibody, and scanning densitometry. The second measurement is to determine the concentration of total HLA antigens expressed in or on a cell using an enzyme-linked immunoassay or a surface binding assay based on W6/32 anti-HLA monoclonal antibody. The quantity of each specific HLA antigen in or on a cell then is calculated from the results of these two measurements. To validate this combined approach, we conducted studies to show that the amounts of different specific HLA antigens measured by this approach were linearly correlated with those measured by FITC-labeled monoclonal antibodies and immunofluorescence flow cytometry in platelets and lymphoblastoid cell lines. We also demonstrated that the relative quantities of different HLA-A and -B antigens determined from the lysates of whole cells were the same as those expressed on the cell surface. These findings indicated that the newly developed combined approach can be applied to quantify each specific HLA-A or -B antigen expressed in or on a cell.

Proportional amplification of individual HLA-A and -B antigens during upregulated expression of total class I HLA molecules

Our recent studies demonstrated that each specific HLA-A or -B antigen is not expressed in equal quantity in cells of an individual and that the relative amounts of different HLA-A and -B antigens are genetically predetermined following Mendelian laws. These findings suggest the potential genetic importance of varied quantitative HLA expression on target cells in determining the sensitivity to cytotoxic T lymphocytes. It would be important to know whether the amounts of different HLA antigens are differentially or proportionally amplified after upregulated expression of total HLA antigens. We have therefore determined the effects of IFN treatment, EBV transformation, and influenza virus infection on the quantitative expression of total HLA antigens and the relative quantities of different specific HLA-A and -B antigens in human fibroblasts cell line and peripheral blood mononuclear leukocytes. In contrast to earlier studies using the transfected HLA genes, our results show that different individual HLA-A and -B antigens are proportionally and not differentially amplified during upregulated expression of total class I HLA molecules. This finding indicates that the genetic predetermination of varied quantitative expression of HLA antigens may play a role in influencing antiviral immunity and disease susceptibility.

White cell reduction in platelet concentrates and packed red cells by filtration: a multicenter clinical trial. The Trap Study Group

BACKGROUND

Most previous studies on white cell (WBC) reduction by filtration have been small-scale studies conducted under tightly controlled laboratory conditions. Their results would be the ideal, rather than what might be expected during routine operation.

STUDY DESIGN AND METHODS

To obtain information on routine filtration of blood components, data have been collected from a large-scale, ongoing, multicenter clinical trial designed to determine the effectiveness of WBC reduction in or ultraviolet B radiation of platelet concentrates before transfusion in preventing platelet alloimmunization and platelet transfusion refractoriness. The WBC content of blood components both before and after filtration was determined by automated cell counters and a manual propidium iodide-staining method, respectively. Platelet and red cell losses during filtration were measured.

RESULTS

The average platelet losses after filtration were 24 +/- 15 percent and 20 +/- 9 percent for apheresis platelets and pooled platelets, respectively. The frequencies at which filtered platelet concentrates contained high levels of residual WBCs (> 5 x 10(6)) were 7 percent and 5 percent for apheresis platelets and pooled platelets, respectively. Further analysis of the platelet filtration data showed that greater numbers of total initial WBCs in the pooled platelets were associated with increased percentages of filtration failure (> 5 x 10(6) residual WBCs). For packed red cells, the average losses during filtration were 23 +/- 4 percent and 15 +/- 3 percent for CPDA-1 units and Adsol units, respectively. The frequencies at which filtered red cells contained > 5 x 10(6) residual WBCs were 2.7 percent for one type of filter and 0.3 percent for another type of filter.

CONCLUSION

There were significant losses of platelets during filtration, which could add to the costs of WBC reduction and lead to possible increases in donor exposures. Filtration failures still occurred, despite careful observation of the standard filtration procedures. The number of total WBCs in pooled platelets before filtration has been identified as an important factor in determining the success of WBC reduction.

A simple quantitative assay for ristocetin cofactor activity using microtiter plate and ELISA plate reader

Ristocetin cofactor activity is the test of choice for diagnosing von Willebrand disease. There is however no simple and precise quantitative method for its rapid determination in the clinical laboratory. We describe here a new approach for measuring ristocetin cofactor activity using an ELISA plate reader. Paraformaldehyde-fixed platelets, diluted plasma samples and ristocetin were mixed and incubated in the wells of a microtiter plate. Platelet agglutination was measured by light absorbance at 405 nm. Measurements of platelet agglutination at 1x to 64x dilution of a normal pooled plasma were used to construct a standard curve. Further characterization showed a significant linear correlation between results determined by the new method and by an aggregometer assay (p < 0.0001), and that the intra- and inter-assay variations were 6% and 17%, respectively. Therefore, the newly developed assay provides a simple and rapid way for precise quantitation of plasma ristocetin cofactor activity.

Lack of immune responsiveness to bovine serum albumin in insulin-dependent diabetes

BACKGROUND

Epidemiologic studies have implicated the ingestion of cow's milk in the pathogenesis of insulin-dependent diabetes mellitus (IDDM). Moreover, in a recent study, 100 percent of patients with new-onset IDDM had antibodies against bovine serum albumin (BSA), with a majority directed against a 17-amino-acid BSA peptide (ABBOS). Cellular immune mechanisms are thought to be the principal mediators of pancreatic beta-cell destruction in IDDM.

METHODS

We measured the responses of peripheral-blood mononuclear cells to BSA and ABBOS or serum IgG anti-BSA antibodies (by particle-concentration fluorescence immunoassay) in 71 patients with IDDM, 55 subjects at various degrees of risk for IDDM, 36 patients with other autoimmune disorders (chronic autoimmune thyroiditis, rheumatoid arthritis, and systemic lupus erythematosus), and 48 normal subjects.

RESULTS

The responses of peripheral-blood mononuclear cells to BSA or ABBOS were positive in 2 of 24 patients with new-onset IDDM, 1 of 25 first-degree relatives of patients with IDDM who were negative for islet-cell antibodies, 2 of 30 first-degree relatives of patients with IDDM who were positive for islet-cell antibodies, 1 of 28 patients with established IDDM, and 1 of 29 normal subjects. Similarly, anti-BSA antibodies were not detected significantly more often in patients with new-onset IDDM (3 of 31, 10 percent) than in normal subjects (1 of 37, 3 percent; P = 0.32). However, many patients with autoimmune disease and subjects at increased risk for IDDM had anti-BSA antibodies (frequency, 10 to 31 percent).

CONCLUSIONS

Anti-BSA antibodies may reflect a general defect in the process of immunologic tolerance associated with a predisposition to autoimmunity rather than immunity specific to beta cells. The absence of cellular immunity to BSA and ABBOS in IDDM does not support a role for this antigen in the pathogenesis of the disorder.

Genetic predetermination of quantitative expression of HLA antigens in platelets and mononuclear leukocytes

In view of the potential functional importance of quantitative expression of HLA antigens, a series of studies were conducted to determine the relative quantities of specific HLA-A and -B antigens expressed in MNLs and platelets of HLA-phenotyped family members and unrelated individuals. An mAb that reacts with a well-defined monomorphic epitope in the alpha 3 domain of the heavy chains of HLA molecules was developed and used to quantify each HLA-A or -B antigen on western blots of IEF gels. The results of these studies demonstrated that the relative quantities of HLA-A and -B antigens in platelets and MNLs of an individual did not change over time. Further studies showed that the relative quantities of HLA-A and -B antigens for haplotypes shared among first-degree relatives were always the same and followed Mendelian inheritance. In contrast, the relative quantities of HLA-A and -B antigens for a haplotype shared by unrelated individuals varied significantly. All these findings support the hypothesis that the quantitative expression of HLA antigens is genetically predetermined and may play important roles in determining disease susceptibility and severity.

The relationship between plasma thrombospondin level and the clinical course of atopic dermatitis

The tests currently used to monitor atopic dermatitis in children--serum IgE level and eosinophil count--are not sensitive enough to accurately track the course of the disease. Because previous studies have shown that atopic dermatitis is an inflammatory disease and because our previous work has shown that plasma thrombospondin level correlates well with the course of other inflammatory diseases, we conducted this study to determine the relationship between plasma thrombospondin level and the severity of skin inflammation in children with atopic dermatitis. Eosinophil count, serum IgE level, and plasma thrombospondin level were measured in 48 children with atopic dermatitis at onset of flare-up, 2 weeks after treatment started, and 2 months after treatment started. The results of all three tests were better after 2 months of therapy than they had been at the initial visit, but only plasma thrombospondin level showed a statistically significant decrease, which coincided with clinical improvement. Plasma thrombospondin level seems to correlate with the clinical course of patients with atopic dermatitis better than do serum IgE level or eosinophil count.

Quantitation and characterization of plasma HLA in neonates of different gestational ages

The functional significance of plasma HLA class I antigens is unclear. They are thought to have an immunomodulatory role and be tolerogenic in transplant settings including the materno-fetal semi-allograft. There is, however, no available data on the concentrations of soluble HLA class I antigens in fetuses or newborns. We therefore determined plasma HLA class I antigen levels in 93 neonates born at different gestational ages and compared them to those in 66 healthy adults. The mean plasma HLA concentration in cord blood obtained from these neonates (0.30 +/- 0.15 microgram/ml, mean +/- SD) was significantly lower (p < 0.0001) than in the adults (0.77 +/- 0.44 microgram/ml). No correlation between the plasma HLA levels and the gestational ages of the neonates was detected. Characterizing the plasma HLA class I antigens by immunoprecipitation and immunoblotting, four different molecular weight forms, 44, 39, 36 and 34 kDa, were recognized. Their distribution in neonates was not different from that in adults. Since the circulating leukocytes are a probable source of plasma HLA class I antigens, we measured the surface HLA expression on leukocytes in 4 neonates and 4 adults by immunofluorescent flow cytometry. The fluorescence intensities on neonatal granulocytes and lymphocytes were 50% of those on corresponding adult cells. This finding suggests that the reduced HLA expression by neonatal leukocytes may be partially responsible for the lower concentration of HLA class I antigens in neonatal plasma.

Enzyme-linked immunoassay for anti-HLA antibodies--an alternative to panel studies by lymphocytotoxicity

In order to provide a simple and specific assay for the detection and quantitation of IgG and IgM anti-HLA antibodies in sera, HLA antigens purified from a pool of 240 random donor platelets were used to develop a solid-phase enzyme-linked immunoassay (EIA). The reference values for identifying the presence of IgG or IgM anti-HLA antibodies were determined by assaying sera from 39 healthy individuals without prior HLA alloimmunization. The assay was evaluated by studying sera from 122 patients who had been characterized previously for panel reactive antibodies by the lymphocytotoxicity assay (LCA). A significant linear correlation between two assays was noted (r = 0.8, P = 0.0001). Further analyses of the data demonstrated that the newly developed EIA has 100% specificity and 95.3% sensitivity as compared with the LCA. Additional studies revealed that patients whose PRA increased or decreased over time were in parallel with antibody levels measured by EIA. When the EIA was used to measure anti-HLA antibody titers, it was more sensitive than the LCA. Since the EIA is sensitive, specific, and technically less demanding, it should provide an useful alternative to reduce the number of the more laborious panel studies for monitoring anti-HLA antibody status in candidates for organ transplantation and recipients of blood transfusions.

Effects of leukocyte depletion and UVB irradiation on alloantigenicity of major histocompatibility complex antigens in platelet concentrates: a comparative study

Recent technologic advancement enables us to prepare leukocyte-depleted or UVB-irradiated platelet concentrates for possible prevention of primary HLA alloimmunization. However, it is yet not known which of these two approaches is more efficacious. Because well-controlled studies cannot be easily conducted in human subjects to answer this question, a series of experiments were performed using a mouse transfusion model. The results showed that 100% of CBA mice with H2k haplotype developed antibody to donor H2d major histocompatibility complex (MHC) antigens after two weekly transfusions of platelet concentrates containing 2000 leukocytes/microL. In contrast, only 50% of the mice became alloimmunized after receiving platelets containing < or = 2 leukocytes/microL. More impressively, none developed anti-H2d antibodies after receiving two platelet concentrates irradiated with 1,200 mJ/cm2 UVB. UVB irradiation was found to be equally effective in reducing the alloantigenicity of platelet concentrates regardless of whether they contained more than a fully immunogenic dose of leukocytes. The antibody titers determined after five weekly transfusions also supported the observation that UVB irradiation was more efficacious than a 3-log leukocyte depletion in the prevention of primary alloimmunization to MHC antigens. In addition, the studies showed that only transfusions of UVB-irradiated platelet products could induce the suppression of immunologic responses to donor MHC antigens in recipients and the induced immunologic suppression could not be further enhanced by gamma irradiation or by leukocyte depletion.

Effect of HLA phenotype and gender on expression of various forms of class I HLA in plasma

To understand the complexity of plasma HLA antigens, the distribution of different molecular weight forms of class I HLA in plasma was investigated in 44 HLA-phenotyped and unrelated individuals. Plasma class I HLA were immunoprecipitated by using the W6/32 anti-HLA monoclonal antibody, separated by SDS-polyacrylamide gel electrophoresis and characterized by immunoblotting with the HC-10 monoclonal antibody. Four different forms of HLA heavy chains (HLA-HC) with relative molecular masses of 44, 39, 36, and 34 kd were detected. Plasma samples from all individuals contained 44 and 36 kd HLA-HC, but varied as to the presence of 39 and 34 kd HLA-HC. Eighteen percent of the individuals did not have any detectable class I HLA with 39-kd heavy chains in their plasma and 61% did not have plasma class I HLA with 34-kd heavy chains. Thus, four different distribution patterns were identified for plasma class I HLA among all individuals included in our study. The distribution patterns in four different individuals were evaluated quarterly and remained unchanged during 1 year follow-up. A significant association of absence of 39-kd plasma class I HLA-HC with female gender (p less than 0.05) and HLA-B7 phenotype (p less than 0.00015) was also found. Further pedigree analyses of four families of HLA-B7-positive and 39-kd HLA-HC-negative probands indicated that genetic factor(s) other than those associated with HLA-B7 allele and female gender is involved in regulating the expression of the plasma class I HLA with 39-kd heavy chains.

Use of 8-methoxypsoralen and ultraviolet-A pretreated platelet concentrates to prevent alloimmunization against class I major histocompatibility antigens

The use of 8-methoxypsoralen (8-MOP) and UV-A irradiation to inactivate contaminating donor leukocytes in platelet concentrates and to prevent primary alloimmunization against donor class I major histocompatibility (MHC) antigens in mice was investigated. CBA/CaH-T6J mice with the H2k haplotype and BALB/cByJ mice with the H2d haplotype were used as donors and recipients, respectively. The mixed leukocyte reaction between these two strains of mice showed that treatment of spleen cells with 500 ng/mL 8-MOP and 5J/cm2 UV-A inhibited 99% of responder and 92% of stimulator function. There was no measurable loss of platelet aggregating activity after the treatment. After two weekly transfusions of platelets without any treatment, 93% of control mice (n = 15) developed anti-H2k antibody. In contrast, only 33% of mice (n = 15) receiving platelets treated with 8-MOP and UV-A became alloimmunized. After six weekly platelet transfusions, all mice became alloimmunized. Nevertheless, the mean titers of anti-H2k antibody in sera of the treated groups were significantly lower than the control groups. One hour posttransfusion recoveries of 51Cr-labeled donor platelets were also higher in mice transfused with the treated platelets. Thus, the pretreatment of platelet concentrates with 8-MOP and UV-A irradiation effectively reduced the alloantigenicity of class I MHC molecules. The implication of this finding in relation to the mechanism by which donor leukocytes allosensitize recipients is discussed.

Guidelines for hemophilia care

The patient with hemophilia has a multitude of medical and psychosocial concerns. The HIV epidemic has drastically exacerbated his needs. Physicians must continue to educate themselves to keep apace of the rapidly changing treatments for hemophilia and for HIV detection and treatment. These recommendations highlight changes that have taken place in the past several months and are up-to-date as of July 1990. It is likely that they will change, however, as more information becomes known about current factor products and better care for HIV infections.

Biochemical characterization of 39-kDa class I histocompatibility antigen in plasma. A secretable membrane protein derived from transmembrane domain deletion

Three human class I major histocompatibility antigens (HLA) with molecular masses of 44, 39, and 36 kDa were identified in plasma by immunoprecipitation and immunoblotting. Further biochemical characterization showed that these antigens in plasma could be fractionated by Sephacryl S-300 column chromatography into two different pools. The 44-kDa intact HLA heavy chains are detected only in pool I and have an apparent molecular weight of 200,000 as determined by calibrated gel filtration column chromatography. The 39- and 36-kDa HLA heavy chains are present only in pool II and have an apparent molecular weight of 50,000. HLA in pool I can be extracted by Triton X-114 detergent, but 39- and 36-kDa plasma HLA in pool II are water soluble and not extractable by Triton X-114. Amino acid sequences of NH2 termini for 44- and 39-kDa plasma HLA are identical to that of cellular HLA. In contrast, the NH2-terminal amino acid sequence for 36-kDa plasma HLA has not been reported previously for any other proteins. Since the loss of both transmembrane domain and cytoplasmic tail at the carboxyl terminus of HLA will generate a 36-kDa protein, the findings suggest that the 39-kDa HLA might be the product of alternatively spliced mRNA with deletion of the exon coding for transmembrane domain. By using polymerase chain reaction and DNA sequencing, the presence of alternatively spliced mRNA with deletion of the transmembrane domain exon was identified in mononuclear leukocytes of peripheral blood. This alternatively spliced HLA mRNA was not detectable in mononuclear leukocytes of an individual who had no 39-kDa plasma HLA. This finding indicates that the alternatively spliced mRNA in mononuclear leukocytes is responsible for the synthesis of a secretable class I HLA.