Obstetric complications in patients with hereditary thrombophilia identified using the LCx microparticle enzyme immunoassay: a controlled study of 5,000 patients

Factor V Leiden (FVL) and prothrombin (PT) G20210A mutations are associated with increased risk of deep venous thrombosis, pulmonary embolism, and obstetric complications. The development of inexpensive and reliable screening methods will assist in defining subpopulations of patients at risk who should undergo testing. We used a method, developed by Abbott Laboratories (Abbott Park, IL), to study 5,000 pregnant women and evaluated the association of obstetric complications with the presence of the FVL and PT G20210A mutations. We found a statistically significant association between FVL and stillbirth. There were also trends toward an association between FVL and placental abruption and between PT G20210A and intrauterine growth retardation. In addition, an association may exist between PT G20210A and preterm delivery for white women. All other parameters studied, including miscarriage and preeclampsia, did not show a statistically significant association with FVL or PT G20210A. These results confirm the association between genetic thrombophilia and selected obstetric complications.

The use of recombinant activated factor VII in three patients with central nervous system hemorrhages associated with factor VII deficiency

BACKGROUND

Recombinant activated factor VII (rFVIIa) is being tested to improve hemostasis in a variety of bleeding disorders. Clinical indications and efficacy are still being evaluated for this product.

CASE REPORT

Over a 17-month period, rFVIIa was used to treat central nervous system hemorrhage in three patients who were found to have isolated FVII deficiency (21%, 40%, 27%). Patient A fell 30 feet, Patient B suffered a motor vehicle accident, and Patient C had a spinal cord hematoma. None of the patients had a history of bleeding diathesis. All three patients received rFVIIa after failing initial treatment with fresh-frozen plasma.

RESULTS

Patient A was treated with 11 doses (initial dose 95 microg/kg; subsequent doses 8-38 microg/kg) over 10 days; Patient B received 13 doses (45-60 microg/kg) over 13 days; and Patient C received 5 doses (12-24 microg/kg) over 4 days. The prothrombin time corrected from 16.2 +/- 1.8 (mean +/- SD) to 11.2 +/- 1.6 seconds after infusion of rFVIIa, but returned to pretreatment level in 14 +/- 4 hours. At the cessation of therapy, all patients showed neurologic improvement. No complications related to the infusion of rFVIIa occurred.

CONCLUSION

The use of rFVIIa may be of value both for its general effect on hemostasis, and specifically in the setting where there is a documented reduction in FVII. Doses lower than those used in patients with FVIII inhibitors appear to be effective in the setting of central nervous system hemorrhage.

Thrombotic microangiopathy associated with unusual viral sequences in HIV-1-positive patients

BACKGROUND

Thrombotic microangiopathy (TMA) is a rare disorder caused by endothelial cell damage. TMA has been associated with the human immunodeficiency virus 1 (HIV-1) infection, yet only a minority of all HIV-1 patients develops TMA. Since HIV-1 has been shown to interact with endothelial cells, we investigated whether certain mutations in the HIV-1 envelope protein are associated with the development of TMA in HIV-1-infected patients.

METHODS

Plasma was obtained from nine HIV-1-positive patients with TMA. Viral loads were determined from the samples and compared with the clinical data. Viral envelope protein sequences from the regions known to be responsible for viral tropism were isolated, sequenced and compared with known HIV-1 isolates. The isolates were expressed as synthetic fusion proteins; binding of these fusion proteins to CD4+ cells as well as to endothelial cell lines was investigated.

RESULTS

The viral loads in patients with HIV/TMA were highly variable with no correlation to the clinical status. Most patients carried macrophage-tropic viral envelope protein sequences and an unusual insertion was found in the V2 variable region. The isolates showed increased CD4 binding, but a direct binding to endothelial cells was not observed.

CONCLUSIONS

Although TMA is generally diagnosed in patients with advanced HIV-1 infection, viral loads per se were not predictive of TMA in this study. While a direct interaction with endothelial cells was not detectable, specific viral envelope mutations were found in a region known to influence viral tropism. Hence, viral-specific factors might contribute to the pathogenesis of HIV-associated TMA.

Universal red blood cells—enzymatic conversion of blood group A and B antigens

Accidental transfusion of ABO-incompatible red blood cells (RBCs) is a leading cause of fatal transfusion reactions. To prevent this and to create a universal blood supply, the idea of converting blood group A and B antigens to H using specific exo-glycosidases capable of removing the immunodominant sugar residues was pioneered by Goldstein and colleagues at the New York Blood Center in the early 1980s. Conversion of group B RBCs to O was initially carried out with alpha-galactosidase extracted from coffee beans. These enzyme-converted O (ECO) RBCs appeared to survive normally in all recipients independent of blood group. The clinical trials moved from small infusions to single RBC units and finally multiple and repeated transfusions. A successful phase II trial utilizing recombinant enzyme was reported by Kruskall and colleagues in 2000. Enzymatic conversion of group A RBCs has lagged behind due to lack of appropriate glycosidases and the more complex nature of A antigens. Identification of novel bacterial glycosidases with improved kinetic properties and specificities for the A and B antigens has greatly advanced the field. Conversion of group A RBCs can be achieved with improved glycosidases and the conversion conditions for both A and B antigens optimized to use more cost-efficient quantities of enzymes and gentler conditions including neutral pH and short incubation times at room temperature. Of the different strategies envisioned to create a universal blood supply, the ECO concept is the only one, for which human clinical trials have been performed. This paper discusses some biochemical and clinical aspects of this developing technology.

Automated detection of the G20210A prothrombin mutation using the LCx microparticle enzyme immunoassay

BACKGROUND

The prothrombin mutation, a G/A transition at position 20210 in the 3' untranslated region of the prothrombin gene, is associated with an increased risk of deep venous thrombosis and obstetrical complications. Several methods have been developed to detect the mutation; however, given the increased demand for this test in risk factor assessment, the development of simple and efficient screening methods has become necessary.

METHODS

We have used a rapid, sensitive, and precise method developed by Abbott Laboratories to detect the prothrombin mutation. The method employs a polymerase chain reaction (PCR) amplification and the Abbot LCx microparticle enzyme immunoassay (MEIA) for detection. This method is able to detect and identify both homozygous and heterozygous genotypes.

RESULTS

Two hundred ninety-six patients with a history of deep venous thrombosis, pulmonary embolism, preeclampsia, or cardiovascular disease and 163 control patients were included in this study. The prevalence of the mutation was 5.74% in the high-risk group and 3.06% in the control group. There was complete agreement between the results from the MEIA detection with those obtained using other detection methodologies, namely standard PCR and restriction fragment length polymorphism (RFLP) analysis.

CONCLUSIONS

The MEIA detection method of the prothrombin mutation represents a simple, fast, and reliable alternative to standard methods of detection and is well suited for use in routine clinical laboratories. The results of our study confirm others' studies showing a greater incidence of G20210A prothrombin gene mutation in patients with an increased risk of venous thrombosis and pulmonary embolism as well as patients with cardiovascular disease and pregnant women with preeclampsia. It reinforces the necessity of including the screening for prothrombin mutation in populations at risk.

Survival of transfused donor white blood cells in HIV-infected recipients

The appearance and expansion of donor white blood cells in a recipient after transfusion has many potential biologic ramifications. Although patients with HIV infection are ostensibly at high risk for microchimerism, transfusion-associated graft-versus-host disease (TA-GVHD) is rare. The purpose of this study was to search for sustained microchimerism in such patients. Blood samples were collected from 93 HIV-infected women (a subset from the Viral Activation Transfusion Study, an NHLBI multicenter randomized trial comparing leukoreduced versus unmodified red blood cell [RBC] transfusions) before and after transfusions from male donors. Donor lymphocytes were detected in posttransfusion specimens using a quantitative Y-chromosome-specific polymerase chain reaction (PCR) assay, and donor-specific human leukocyte antigen (HLA) alleles were identified with allele-specific PCR primers and probes. Five of 47 subjects randomized to receive nonleukoreduced RBCs had detectable male lymphocytes 1 to 2 weeks after transfusion, but no subject had detectable male cells more than 4 weeks after a transfusion. In 4 subjects studied, donor-specific HLA haplotypes were detected in posttransfusion specimens, consistent with one or more donors' cells. None of 46 subjects randomized to receive leukoreduced RBCs had detectable male lymphocytes in the month after transfusion. Development of sustained microchimerism after transfusion in HIV-infected patients is rare; HIV-infected patients do not appear to be at risk for TA-GVHD.

Transfusion to blood group A and O patients of group B RBCs that have been enzymatically converted to group O

BACKGROUND

The transfusion of ABO-incompatible RBCs is the leading cause of fatal transfusion reactions. Group O RBCs, lacking terminal immunodominant A and B sugars to which humans are immunized, are safe for transfusion to persons of any ABO blood group. With the use of a recombinant alpha-galactosidase to remove terminal galactose from group B RBCs, the safety and efficacy of enzyme-converted group-B-to-group-O (ECO) RBC components were studied in transfusion-dependent patients.

STUDY DESIGN AND METHODS

Twenty-four patients (blood groups A and O) were randomly assigned to receive transfusion(s) of either ECO or control group O RBCs. If a second transfusion was given, the other blood component was administered.

RESULTS

Twenty-one patients were given ECO RBCs; 18 also underwent control transfusions. One patient received only a small aliquot for RBC survival studies, instead of a full-unit transfusion, because his serum was incompatible with ECO RBCs. No adverse events occurred. Both ECO and control transfusions resulted in appropriate Hb increments and comparable (51)Cr-labeled RBC survival studies. One patient developed a transient, weak-positive DAT, without hemolysis. Two weeks after transfusion, 5 of 19 evaluable ECO RBC recipients had increases in anti-B titers.

CONCLUSION

ECO RBCs were comparable to group O cells for safety and efficacy in this study. The clinical significance of the increase in anti-B and of occasional serologic incompatibilities with ECO RBCs is unclear. If strategies can be developed to remove A epitopes, enzymatic conversion could be used to create a universal (group O) donor blood supply.

Prospective analysis suggests susceptibility genes for deficiencies of IgA and several other immunoglobulins on the [HLA-B8, SC01, DR3] conserved extended haplotype

The extended major histocompatibility complex (MHC) haplotype [HLA-B8, SC01, DR3] is increased in frequency among patients with immunoglobulin (Ig)A deficiency and common variable immunodeficiency. Because the genomic region from HLA-B to HLA-DR/DQ is virtually the same on all instances of the haplotype in the general population, we reasoned that all independent instances of [HLA-B8, SC01, DR3] carry MHC susceptibility genes for these disorders. To define immunoglobulin deficiencies determined by genes on this haplotype and their mode of expression and penetrance, serum immunoglobulin class and IgG subclass concentrations were determined prospectively in homozygotes and heterozygotes of this haplotype and in Caucasian controls. Prevalence of individual immunoglobulin deficiencies in persons with [HLA-B8, SC01, DR3] ranged from 13% to 37%, significantly higher than rates in non-carriers or general controls. We found significantly increased frequencies of IgA and IgG4 deficiency only in homozygotes (13.3% and 30%, respectively) compared with heterozygotes (1.7% and 3.4%) or non-carriers (1.6% each), suggesting recessive expression. In contrast, IgD and IgG3 deficiencies were significantly more common in both homozygotes (36.7% and 30%) and heterozygotes (20.3% and 17.5%) compared with controls (4.9% and 3.4%), suggesting dominant inheritance. These results indicate multiple distinct susceptibility genes, some recessive and others dominant, for deficiency of IgA, IgD, IgG3 or IgG4 (but not for IgE, IgG1, IgG2 or IgM) on [HLA-B8, SC01, DR3]. These observations may also help to explain the observed associations of [HLA-B8, SC01, DR3] with both IgA deficiency and common variable immunodeficiency and the common occurrence of IgG subclass deficiencies in some patients with IgA deficiency.

Lowering the hemoglobin cutoff for female plateletpheresis donors

BACKGROUND

The standards of the American Association of Blood Banks describe a minimum hemoglobin level of 12.5 g per dL for apheresis donors. Until 1995, the authors' institution accepted occasional platelet donors with a lower minimum hemoglobin (11.5 g/dL), if accompanied by medical director approval.

STUDY DESIGN

All donation records from a 6-month period before 1995 were retrospectively reviewed to determine whether this lower hemoglobin cutoff adversely affected either the safety of the platelet donation process or donors' subsequent hemoglobin levels.

RESULTS

Of 450 donations, 56 (12%, Group 1) were from donors with hemoglobin concentrations between 11.5 and 12.4 g per dL (2 donations from 1 man; 54 donations from 45 women). The remaining 394 donations (88%, Group 2) came from donors with hemoglobin concentrations > or = 12.5 g per dL (216 donations from 118 men; 178 donations from 119 women). The frequency of donor reactions was acceptable (Group 1, 11%; Group 2, 6%); 2 percent of donations by Group 1 donors and 1 percent by Group 2 donors were terminated because of these reactions. Of 46 donors in Group 1, 30 returned to donate platelets again at a later time; at least once, 23 (77%) had a hemoglobin > or = 12.5 g per dL. Ten donors in Group 1 returned for additional donations within 56 days; no meaningful decrease in hemoglobin levels occurred. A hemoglobin cutoff of 12.5 g per dL during the study period would have excluded 1 percent of platelet donations by men and 23 percent by women.

CONCLUSION

The data demonstrate that the lower hemoglobin cutoff of 11.5 g per dL is a safe and relevant threshold for accepting female plateletpheresis donors and would allow more participation by women in blood donor programs.

Making Landsteiner's discovery superfluous: safety and economic implications of a universal group O red blood cell supply

The risks of ABO-mediated acute immune hemolytic transfusion reactions continue to bedevil modern transfusion services. Of particular concern, the incidence of transfusion fatalities has not changed over time, in stark comparison to the fall in risks of infectious diseases. This article reviews the approaches employed to combat aspects of ABO transfusion errors. The advantages of a universal group O donor pool are considered, and some innovative approaches for achieving this goal, including enzymatic modification of the red cell membrane, the epitope masking through the use of polyethylene glycol, are described. The impact of a group O blood supply on transfusion practices, and on costs to healthcare system, are considered.

Unexpected citrate toxicity and severe hypocalcemia during apheresis

BACKGROUND

The citrate anticoagulant used during apheresis procedures is considered a safe medication because it is rapidly metabolized by the donor. However, acute, life-threatening hypocalcemia is possible if the infusion rate of citrate is increased.

CASE REPORT

A 54-year-old woman with metastatic breast cancer, but otherwise in good health, had just begun a fifth collection of hematopoietic peripheral blood progenitor cells by leukapheresis. The instrument's self-loading apheresis kit was primed uneventfully. Seven minutes into the procedure, the patient developed signs and symptoms suggesting severe hypocalcemia, including muscle spasms, chest pain, and hypotension. The citrate bag was discovered to have emptied, and a section of the anticoagulant tubing was protruding outside of the rotary pump. The patient's ionized calcium level was 0.64 mmol per L (normal range, 1.18-1.38 mmol/L). In subsequent experiments where the anticoagulant tubing was either improperly loaded at the outset or partially pulled out of the rotary pump, no instrument alarms sounded.

CONCLUSION

Citrate toxicity and life-threatening hypocalcemia can occur if the anticoagulant line of an apheresis instrument is not properly housed in its rotary pump or becomes disengaged during the procedure. Instrument manufacturers are encouraged to consider designs that allow the direct measurement of the volume of citrate delivered. In the interim, periodic visual and tactile confirmation of tubing placement during apheresis procedures is prudent.

Possible association between the Norplant contraceptive system and thrombotic thrombocytopenic purpura

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a rare, potentially fatal disease of uncertain etiology. Early diagnosis and treatment are essential to patient survival. The ]purpose of this report is to describe three patients with levonorgestrel implants (Norplant system) who developed TTP.

CASES

A 24-year-old woman with levonorgestrel implants in place for 7 months was admitted to our hospital for treatment of TTP. Clinical symptoms included easy bruising, menorrhagia, headaches, and fever; laboratory evaluation revealed thrombocytopenia (18 x 10(9)/L) and microangiopathic hemolytic anemia. She was treated with plasmapheresis, and the implants were removed. Through the Freedom of Information Act, we reviewed all adverse events associated with Norplant use reported to the Food and Drug Administration (FDA) as of the end of 1992. Two additional cases were identified.

CONCLUSIONS

Although a causal relationship between progestogen-only contraceptives and TTP is not established by the data presented, these three cases may represent an increased incidence of TTP in women using levonorgestrel implants. Patients who receive Norplant should be advised to seek medical attention if symptoms appear. Physicians and other health care providers should be aware of the possible association between use of the Norplant system and TTP and are urged to report similar cases to the FDA.

Hemolytic disease of the newborn due to the Scianna antibody, anti-Sc2

BACKGROUND

Alloantibodies to the low-frequency antigen Scianna 2 (Sc2) are uncommon and not previously reported to cause immune hemolysis.

CASE REPORT

A group B, Rh-negative infant born to a group B, Rh-positive mother had a 2+ direct antiglobulin test, as well as modest hyperbilirubinemia and a hematocrit of 45 percent. Ongoing immune hemolysis led to a hematocrit of 17.3 percent on Day 20 of life, and the infant required hospitalization and red cell transfusions. The routine maternal antibody screen was negative, but anti-Sc2 was detected during work-up for a low-frequency red cell antigen, and the father's red cells typed as Sc:1,2.

CONCLUSION

Anti-Sc2 can cause clinically significant hemolytic disease of the newborn. Although the antibody is uncommon, its frequency and hemolytic potential may be underappreciated, in part because investigations often are not carried out in the infant whose red cells are ABO-incompatible with maternal blood.

Red cell loss following orthopedic surgery: the case against postoperative blood salvage

BACKGROUND

Expensive devices have been developed for the collection and transfusion of blood salvaged after hip or knee arthroplasty.

STUDY DESIGN AND METHODS

The volume of salvaged red cells was measured for the first 6 hours after operation. This volume was compared to total red cell loss during hospitalization and to the volume of allogeneic red cells transfused.

RESULTS

Mean postoperative red cell loss in 31 patients following hip replacement was 55 +/- 29 mL and that in 20 patients following knee replacement was 121 +/- 50 mL. The 6-hour wound drainage represented 8.7 and 16.8 percent of overall red cell loss during hospitalization for hip and knee replacement, respectively. The transfusion of postoperatively salvaged red cells would have supplanted transfusion of less than one-third of a unit of allogenic blood after hip replacement and two-thirds of a unit after knee replacement. Only three patients (5.9%) lost red cell volume in the drainage equivalent to or in excess of 1 unit of red cells (180 mL). The volume of red cells salvaged postoperatively bore no relationship to perioperative red cell losses as a whole.

CONCLUSION

The relatively small red cell loss in the postoperative period in most arthroplasty patients does not appear to justify the routine use of this technique for the recovery of autologous blood.

Guidelines for blood utilization review

Hospitals are required by accrediting agencies to perform blood utilization review. Specific areas that must be addressed are the ordering, distribution, handling, dispensing, and administration of blood components. Monitoring the effects of transfusion on patients is also required. The format of the review process and the criteria for appropriate blood utilization must be developed by each institution. This article provides examples of areas that can be reviewed and procedures that may be used. However, the suggested laboratory values must not be interpreted as defining indications or criteria for transfusion. Each transfusion committee, or its equivalent, is responsible for developing its own institutional blood utilization procedures and audit criteria. Review and approval by the medical staff prior to implementation are essential. The procedures must also be reviewed and revised on a regular basis.

Cellular recognition and HLA restriction of a midsequence HBsAg peptide in hepatitis B vaccinated individuals

Vaccination with native HBsAg results in both a humoral and a cellular immune response in humans. In individuals who responded to vaccination, the HBsAg (S region) specific response, as measured by cell proliferation, diminished significantly after 12 weeks, a time when the antibody response was still vigorous. Reduced and nonreduced HBsAg were equivalent in eliciting lymphocyte proliferation. Anti-MHC class II monoclonal antibodies were used in blocking studies to demonstrate that anti-HLA-DR but not anti-HLA-DQ or anti-HLA-DP inhibited specific lymphocyte proliferation to HBsAg. Both the monomer (reduced) and dimer (nonreduced) forms of an immunodominant midsequence HBsAg peptide (amino acid residues 139-146) produced lymphocyte proliferation roughly comparable to that induced by whole HBsAg in 6 of 7 responders immunized with whole HBsAg and the peptide-induced proliferation was blocked by anti-HLA-DR but not by anti-HLA-DP antibodies. These results suggest that HBsAg p 139-146 is a major immunodominant peptide of HBsAg and is restricted by HLA-DR.

Membrane properties of erythrocytes in subjects undergoing multiple blood donations with or without recombinant erythropoietin

To examine the characteristics of 'young' human red cells, we studied blood from seven healthy male volunteers who developed systemic reticulocytosis during a 3-week blood donation period. Each of these subjects donated a total of 6 units (450 ml/unit) of blood (2 units/week for 3 weeks) with subcutaneous recombinant erythropoietin (SC rEPO; 200 U/kg daily for 3 weeks). Two of these subjects were also studied with a similar protocol in the absence of rEPO (4.5 +/- 0.5 units donated). SC rEPO administration was associated with an increased K content of the erythrocyte and with the appearance of hypochromic cells, which were initially normocytic and then became normochromic and microcytic. Measurements of cation transport revealed that, with the exception of the Na-K-Cl cotransport, all the systems studied increased their activities following blood donations with or without SC rEPO. The increase was highest in the K-Cl cotransport (2- and 5-fold for control and rEPO parts of the study, respectively), while the Na-K pump increased slightly in control and 40% with rEPO. The Na-Li countertransport increased 40% and 100% in the control and rEPO parts of the study, respectively. Concomitant with increased ion transport activity, electron microscopic studies of plasma and red cells of subjects receiving SC rEPO showed the presence of circulating exosomes and cytoplasmic multivesicular bodies. The transferrin receptor was detected in the circulating exosomes, thereby providing evidence that, as do nonhuman red cells, maturing human reticulocytes shed exosome-associated transferrin receptors.

Red blood cell regeneration induced by subcutaneous recombinant erythropoietin: iron-deficient erythropoiesis in iron-replete subjects

Limited red blood cell (RBC) regeneration often prevents collection of sufficient blood from autologous donors. We studied the effects of subcutaneous recombinant erythropoietin (rEPO) in subjects making frequent blood donations. Six healthy iron-replete male subjects took rEPO (200 U/kg) subcutaneously daily, and donated blood (450 mL) twice a week for 3 weeks. During a control study, these subjects also attempted twice-weekly blood donations without rEPO. Four other males given rEPO, including one with idiopathic hemochromatosis, waited until day 8 to begin blood donations. All healthy subjects took oral ferrous sulfate. Subcutaneous rEPO given with blood donations resulted in a marked reticulocytosis (mean peak value 568 +/- 159 x 10(9)/L v 235 +/- 77 x 10(9)/L, control study; P < .05), and enhanced RBC production at 28 days (1,208 +/- 227 mL v 719 +/- 161 mL, P < .05). rEPO in advance of blood donations was slightly less effective in normal subjects (941 +/- 139 mL, P < .05); however, the subject with hemochromatosis produced substantially more RBCs (1,764 mL) than any normal subject. rEPO-treated normal subjects (but not the rEPO-treated patient with hemochromatosis or untreated controls) produced iron-deficient RBCs with elevated zinc protoporphyrin levels and low hemoglobin content. These cells appeared within 1 week of rEPO administration and before laboratory confirmation of depleted iron stores. Thus, subcutaneous rEPO is an effective stimulant of erythropoiesis in nonanemic blood donors. However, in addition to eventual depletion of iron stores, early functional iron deficiency affects response to the drug.

A comparative study of blood warmer performance

Massive transfusions of refrigerator-temperature blood may induce hypothermia and life-threatening arrhythmias; for this reason a variety of devices have been developed for rapid blood warming. Blood warmers available in the United States use one of three warming technologies: dry heat, water bath, or countercurrent heat exchange. In the current study we evaluated blood warmers representative of each technology for speed and extent of heat transfer: the Fenwal blood warmer (Fenwal Laboratories; dry heat), the DW-1000 (American Pharmaseal Co.; dry heat), the FloTem IIe (DataChem Inc.; dry heat), the Hemokinetitherm (Dupaco Inc.; water bath), and the H250 and H500 (Level 1 Technologies; countercurrent heat exchange). Only one countercurrent heat instrument (the H500) was able to heat blood > or = 33 degrees C at target flow rates > or = 250 ml/min. Dry heat and water bath blood warmers were unable to warm blood > or = 33 degrees C at target flow rates > or = 100 ml/min. High resistance to flow with the proprietary tubing required for one instrument (the Hemokinetitherm) prevented tests of blood warming at rates > 150 ml/min. We found that instruments that used countercurrent technology warmed blood and saline more effectively than did blood warmers that used either dry heat or water bath technology. Our study also demonstrated the need for close control and standardization of experimental conditions in the evaluation of blood warming devices.

Comparison of two transfusion strategies after elective operations for myocardial revascularization

We performed a prospective, randomized trial of two different strategies for postoperative packed red blood cell replacement in 39 autologous blood donors undergoing elective myocardial revascularization. The "liberal" group received blood to achieve a hematocrit value of 32%, and the "conservative" group received transfusions for a hematocrit value less than 25%. Although the groups had significantly different mean hematocrit values from the fourth postoperative hour (28.7% versus 31.2%) through the fifth postoperative day (28.4% versus 31.3%), there were no significant differences in fluid requirement, hemodynamic parameters, or hospital complications. Significantly fewer units of packed cells were required in the conservatively transfused group (20 units/20 patients) compared with the liberally transfused group (37 units/18 patients) (p = 0.012). Exercise tests were performed on the fifth and sixth postoperative days, with a transfusion being given to the conservative group between tests. Although a significant improvement in exercise endurance occurred in the conservative group receiving a transfusion (p = 0.008), no significant difference in duration or degree of exercise was demonstrated between the two groups on either day. In comparing these two groups of profoundly anemic patients, we identified no adverse consequence associated with the greater degree of hemodilution and could identify no correlation between hematocrit value and exercise capacity. We conclude that although the limits of hemodilution are still poorly defined, postoperative blood transfusion in revascularized patients should be guided by clinical indications and not by specific hematocrit values.

The immune response to hepatitis B vaccine in humans: inheritance patterns in families

We have recently shown that the human antibody response to the hepatitis B virus surface antigen (HBsAg) vaccine is major histocompatibility complex (MHC) associated. In studies of nonresponders to the vaccine, we found an increased incidence of individuals homozygous for human histocompatibility leukocyte antigen (HLA) proteins associated with the extended (conserved) haplotype [HLA-B8,SC01,DR3]. In later prospective vaccination trials, we showed that none of five individuals homozygous for this haplotype developed more than 1,300 radioimmunoassay (RIA) units of antibody (mean, 467 RIA units), while all heterozygotes made at least 2,500 RIA units (mean antibody level, 15,608 units). Our results suggested that [HLA-B8,SC01,DR3] lacks an immune response gene for HBsAg, and that response is inherited in a dominant fashion. To provide further evidence for this hypothesis, we have now analyzed the results of HBsAg immunization in families. 43 members of 10 families were immunized with the hepatitis B vaccine, including seven families where at least one member bore the haplotype [HLA-B8,SC01,DR3], and three families where one member had already received, but failed to respond to, the vaccine. In two of these three families, the presence of [HLA-B8,SC01,DR3] was subsequently found. Of nine MHC-identical sibling pairs in the study, both members of eight pairs had similar antibody responses (five nonresponder and three responder pairs). In all families with such sibling pairs, including the discordant pair, rank-ordering members by antibody level demonstrated that no relative's value came between the sibling pair values. Furthermore, of nine [HLA-B8,SC01,DR3]-haplotype-homozygous individuals, six were nonresponders, and two others had only low-normal responses. [HLA-B8,SC01,DR3]-heterozygous family members always had higher levels of antibody than their homozygous relatives. Linkage analysis of nonresponse to HLA haplotypes revealed a maximum likelihood LOD (logarithm of the odds) score of 6.3 at a recombination fraction of 0.1. The MHC association with lack of antibody response to HBsAg was not seen with tetanus immunization, where 1 of 20 HBsAg responders and 1 of 21 poor or nonresponders had tetanus titers of less than 1:512; both tetanus nonresponders were [HLA-B8,SC01,DR3] heterozygotes. Our results indicate that: (a) response to the HBsAg vaccine is MHC linked, and inherited in a dominant fashion; (b) an abnormal or missing immune response (Ir) gene for HBsAg is a characteristic of most examples of the extended haplotype [HLA-B8,SC01,DR3]; and (c) other haplotypes also have abnormal or missing Ir genes for HBsAg.

Limited efficacy of leukopoor platelets for prevention of febrile transfusion reactions

Leukopoor red cell components have a reduced incidence of febrile transfusion reactions. An analogous efficacy for leukopoor platelets has not been convincingly established. The authors analyzed the transfusion records of 36 patients (26 women, 10 men) who received leukopoor platelets following febrile reactions to unmodified platelets. These patients received 409 unmodified transfusions (mean/patient 11) with 84 febrile reactions (rate 20.5%). Reaction rates to unmodified, non-HLA-matched single donor platelets (14.0%) and HLA-matched platelets (6.5%) were significantly lower than to pooled concentrates (27.2%) (P less than .01 and P less than .001, respectively). Of 623 leukopoor transfusions (mean/patient 17), 84 resulted in reactions (13.5%). Although leukodepletion significantly lowered the overall reaction rate as compared with unmodified products (P less than .02), a majority of patients (28 of 36) continued to have reactions. When individual reaction rates to unmodified and leukopoor transfusions were compared, only two patients showed a significant decrease in their reaction rate with leukopoor platelets. It appears that most susceptible patients continue to react to leukopoor platelets, particularly when pooled concentrates are used, and many patients show no reduction in reaction rate.

Ceftazidime-induced hemolysis in a patient with drug-dependent antibodies reactive by immune complex and drug adsorption mechanisms

A 35-year-old woman developed acute intravascular hemolysis within five days of beginning a course of ceftazidime. The direct antiglobulin test became strongly positive with both anti-IgG and anticomplement. The serum contained an antibody that, in the presence of ceftazidime, sensitized unmodified reagent cells with IgG and complement (immune-complex type). The serum also agglutinated ceftazidime-pretreated cells at room temperature and 37 degrees C (drug-adsorption type). Retrospective testing disclosed that the drug adsorption antibody, which had been present before the current course of antibiotics, was not demonstrable during the hemolysis. The reactivity of the immune complex antibody, which developed by the second day of ceftazidime, paralleled the degree of hemolysis and the strength of the direct antiglobulin test. The authors believe that this patient had two separate ceftazidime-dependent antibodies and that the antibody reactive by immune complex mechanism mediated an episode of acute intravascular hemolysis.

The cellular basis for lack of antibody response to hepatitis B vaccine in humans

We had previously obtained evidence that among normal subjects the humoral antibody response to hepatitis B surface antigen (HBsAg) was bimodally distributed with about 14% of subjects producing less than 1,000 estimated radioimmunoassay RIA units. From the study of major histocompatibility complex (MHC) markers in the very poor responders who produced less than 36 estimated RIA units of antibody, it appeared that there was an excess of homozygotes for two extended haplotypes [HLA-B8, SC01, DR3] and [HLA-B44, FC31, DR7]. This finding suggested that a poor response was inherited as a recessive trait requiring nonresponse genes for HBsAg on both MHC haplotypes and was strengthened by finding a much lower antibody response among prospectively immunized homozygotes for [HLA-B8, SC01, DR3] compared with heterozygotes. In the present study, we have analyzed the cellular basis for nonresponse to this antigen by examining antigen-specific proliferation of T cells from responders and nonresponders in the presence and absence of autologous CD8+ (suppressor) cells. Peripheral blood cells from nonresponders to HBsAg failed to undergo a proliferative response to recombinant HBsAg in vitro, whereas cells from responders proliferated vigorously. This failure of cells from nonresponders to proliferate was not reversed in cell mixtures containing CD4+ and antigen-presenting cells devoid of CD8+ cells. There was no difference between responders and nonresponders with respect to the number of circulating T cells or their subsets, or the proliferative response to mitogens such as pokeweed or phytohemagglutinin or another antigen, tetanus toxoid. Our results indicate that our HBsAg nonresponding subjects have a very specific failure in antigen presentation or the stimulation of T helper cells, or both. Our evidence is against specific immune suppression as the basis for their nonresponsiveness. The failure of antigen presentation or T cell help is consistent with recessive inheritance of nonresponsiveness and suggests that response is dominantly inherited.

Directed-donor programs may adversely affect autologous donor participation

One hundred autologous whole blood donors (11 men, 89 women; 49 preoperative, 51 prenatal) completed a questionnaire concerning their motivations as autologous donors, their perceptions of the relative safety of blood donor options, and their interest in directed donations. Concern about acquiring AIDS from transfusion was the most prevalent reason for autologous donation. Nearly all participants knew that autologous blood was safer than volunteer blood, and most also believed that directed-donor blood was safer than volunteer blood. Most would have used a directed-donor program if available, particularly if they were ineligible as autologous donors. Furthermore, their interest in directed donations was unaffected by written material, provided pathway through the questionnaire, that included a statement that no scientific evidence exists to support directed donations' being safer than volunteer blood. One donor in five believed that autologous and directed donations were equivalent in safety, and 19 (15 of whom were prenatal donors) indicated that they probably or surely would not have participated in the autologous program if directed donations had been available. This study demonstrates that a sizable proportion of autologous donor candidates might not participate if a directed donation program were available. The unrestricted availability of directed donations may thus contribute to suboptimal use of autologous donor programs.

Febrile reactions after platelet transfusion: the effect of single versus multiple donors

Febrile reactions to platelet transfusions are a common problem. The platelet transfusion records from a 30-month period were analyzed to determine 1) when reactions occur in a transfusion sequence; 2) how frequently they recur; and 3) whether the choice of multiple-donor (pooled concentrates) or single-donor components (unmatched apheresis and HLA-compatible apheresis platelets) affected the reaction rate. Overall, 18.7 percent of all patients receiving platelets experienced reactions. A subset of 85 patients, who began platelet support with unmodified components during the study interval, were analyzed in detail. This group received 1204 unmodified transfusions (mean, 14.2/patient), which were associated with 171 reactions (per-transfusion reaction rate, 14.2%). Despite a higher mean white cell content, the transfusion of 438 unmatched single-donor platelets (10.84 x 10(8) white cells, 8.4% reaction rate) resulted in reactions significantly less often than did that of 583 pooled concentrates (8.53 x 10(8) white cells, 21.4% reaction rate) (p less than 0.001). The rate of reaction to HLA-compatible platelets (9/183 transfusions, 4.9%) was not significantly different from that to unmatched single-donor platelets. The use of platelet components from one donor, as opposed to multiple donors, may provide an effective means of reducing the incidence of febrile reactions.

The major histocompatibility complex: the value of extended haplotypes in the analysis of associated immune diseases and disorders

Major histocompatibility complex antigens are critical to an animal's immune response. In most animals, the extreme polymorphism of MHC molecules complicates studies of the role of this complex in the immune response. In mice, however, MHC haplotype-homozygous inbred strains have been developed which are invaluable in the study of the immune system and the search for immune response genes. The human MHC bears many similarities to its murine equivalent with regard to antigen structure and polymorphism; furthermore, a number of combinations of specific MHC alleles between HLA-B and HLA-DR/DQ (extended haplotypes) are found in people more commonly than predicted by individual allele frequencies. Over 30 percent of Caucasian haplotypes are extended haplotypes, and over 55 percent of individuals have at least one extended haplotype. Examples of the same extended haplotype, even in unrelated individuals, should either all have or lack any gene within the MHC region. The value of considering extended haplotypes in searching for associations between the MHC and diseases, or immune response, is shown in three examples: congenital adrenal hyperplasia, hepatitis B immunization, and transfusion-associated graft-versus-host disease.

Major histocompatibility complex markers and red cell antibodies to the Rh (D) antigen. Absence of association

Between 20 and 35 percent of Rh(D) antigen-negative individuals do not develop antibodies to D even after multiple transfusions of Rh-positive red cells. To evaluate the possibility that antibody production after exposure to the D antigen was related to a major histocompatibility complex immune response gene, analysis of the HLA genotypes of 38 Rh-sensitized women and their families was performed. No significant deviations were found in the frequency of any individual HLA class I, II, or III allele or of any extended haplotype (fixed allelic combinations of HLA-B, HLA-DR, and the complement components BF, C2, C4A, and C4B). Type 1 errors due to the extreme allelic polymorphism of the HLA system, as well as the ethnic variation in patient groups, may have contributed to HLA allele-antibody responder relationships reported in earlier studies.

Evaluation of a blood warmer that utilizes a 40 degrees C heat exchanger

Most commercial blood warmers are unable to warm blood components to greater than 35 degrees C at rapid flow rates (greater than 100 mL/min) because of problems with inefficient heat transfer and resistance to the flow of blood through the instrument's tubing. A new blood warmer, using a closed-flow 40 degrees C counter-current water bath and large-bore tubing, is able to warm cold (10 degrees C) packed red cells to temperatures greater than 35 degrees C even at flow rates of 500 mL per minute. To evaluate the effects on red cells of prolonged exposure to the 40 degrees C heat exchanger, blood from five volunteers stored for 42 days in AS-1 was run through the blood warmer using flow rates equivalent to the transfusion of a unit of blood over 4 hours. Compared with unwarmed blood, these blood units showed no significant changes in plasma hemoglobin, mean corpuscular hemoglobin concentration, potassium, ATP, pH, and osmotic fragility. In vivo survivals of chromium-51-labeled warmed autologous red cells were greater than 75 percent in four volunteers and 49.5 percent in the fifth volunteer, whose abnormally low unwarmed red cell ATP level suggested a storage problem. Thus, this blood warmer, which warms blood efficiently at high flow rates, causes no red cell damage, even with prolonged exposure of old red cells to the 40 degrees C heat exchanger.

Increased preoperative collection of autologous blood with recombinant human erythropoietin therapy

To study whether the administration of recombinant human erythropoietin increases the amount of autologous blood that can be collected before surgery, we conducted a randomized, controlled trial of erythropoietin in 47 adults scheduled for elective orthopedic procedures. The patients received either erythropoietin (600 units per kilogram of body weight) or placebo intravenously twice a week for 21 days, during which time up to 6 units of blood was collected. Patients were excluded from donation when their hematocrit values were less than 34 percent. All patients received iron sulfate (325 mg orally three times daily). The mean number of units collected per patient (+/- SE) was 5.4 +/- 0.2 for the erythropoietin group and 4.1 +/- 0.2 for the placebo group. The mean red-cell volume donated by the patients who received erythropoietin was 41 percent greater than that donated by the patients who received placebo (961 vs. 683 ml, P less than 0.05). Only 1 of the 23 patients treated with erythropoietin was unable to donate greater than or equal to 4 units (4 percent) as compared with 7 of the 24 patients who received placebo (29 percent). No adverse effects were attributed to erythropoietin. We conclude that recombinant human erythropoietin increases the ability of patients about to undergo elective surgery to donate autologous blood.

Strategies for the review of transfusion practices

The intent of this report is to familiarize health care professionals with the concept of effective quality assurance in regard to blood use. Although evaluation of the appropriateness of transfusion therapy is now required by the Joint Commission on Accreditation of Health Organizations, health care facilities have little experience with this aspect of professional quality assurance. To this end, the Committee on Transfusion Practices of the American Association of Blood Banks, in Arlington, Va, in this report has provided examples of indications and audit criteria for individual blood components and products and commented on areas of controversy surrounding their use. Audit criteria from different institutions may vary because of differences in local interpretation of the indication, different patient populations, and, in some instances, the availability of blood and laboratory services. Several approaches to the review of transfusion practices are discussed in relation to clinical settings and pertaining to particular blood components. It is evident from these examples that there will be an increased need for trained personnel to perform the initial review process as well as for physicians trained in transfusion medicine to oversee the transfusions and provide the necessary consultation.

Autologous blood donations prior to elective cardiac surgery. Safety and effect on subsequent blood use

Blood transfusions are frequently necessary for patients having open heart surgery. Although autologous blood is free of such risks as transfusion-transmitted diseases, the safety and effectiveness of autologous donations by cardiac patients are debated. We analyzed the records of 291 consecutive patients undergoing elective open heart surgery. One hundred seven (36.8%) donated between 1 and 6 U of autologous blood (mean, 3.0 +/- 1.5 U) before undergoing surgery. First-time elective coronary artery bypass surgery was the most common indication for autologous donation (90.6% of autologous donors). Problems following donations were infrequent (2 of 326 donations) and without long-term consequences. Among patients having coronary artery bypass surgery who donated autologous blood, 27% required homologous blood transfusions as compared with 82% of other patients undergoing the same procedure. We conclude that autologous blood donations are safe for patients with cardiac disease and effective in significantly reducing homologous blood needs in patients undergoing elective coronary artery bypass surgery.

Genetic prediction of nonresponse to hepatitis B vaccine

In previous studies of the antibody response to hepatitis B vaccine in 598 subjects who received a full course of vaccination, we observed a bimodal response, with about 14 percent producing less than approximately 1000 radioimmunoassay (RIA) units. An analysis of the major histocompatibility complex (MHC) HLA and complement types of 20 of the subjects with the lowest responses indicated a greater-than-expected number of homozygotes for the extended or fixed MHC haplotype [HLA-B8, SC01, DR3]. This finding suggested that the lack of a normal response was a recessive MHC-linked trait. In this study, we prospectively vaccinated five homozygotes and nine heterozygotes for this haplotype in the expectation that the homozygotes would produce much lower levels of antibody than the heterozygotes. When the antibody response was assessed two months after the third injection, four of the five homozygotes had produced very low levels (approximately 1000 units or less) of antibody (mean, 467 RIA units; range, less than 8 to 1266), whereas all nine heterozygotes produced more than 2500 RIA units (mean, 15,608; range, 2655 to 28,900) (P less than 0.01). We conclude that the usual response to hepatitis B surface antigen is due to the presence of a dominant immune-response gene in the MHC and that a low response is due to the absence of such a gene and the presence on both chromosomes of MHC haplotypes (such as [HLA-B8, SC01, DR3]) that indicate such a response.