Risks of restrictive red blood cell transfusion strategies in patients with cardiovascular disease (CVD): a meta-analysis

AIM

To evaluate the risks of restrictive red blood cell transfusion strategies (haemoglobin 7-8 g dL^-1 ) in patients with and without known cardiovascular disease (CVD).

BACKGROUND

Recent guidelines recommend restrictive strategies for CVD patients hospitalised for non-CVD indications, patients without known CVD and patients hospitalised for CVD corrective procedures.

METHODS/MATERIALS

Database searches were conducted through December 2017 for randomised clinical trials that enrolled patients with and without known CVD, hospitalised either for CVD-corrective procedures or non-cardiac indications, comparing effects of liberal with restrictive strategies on major adverse coronary events (MACE) and death.

RESULTS

In CVD patients not undergoing cardiac interventions, a liberal strategy decreased (P = 0·01) the relative risk (95% CI) (RR) of MACE [0·50 (0·29-0·86)] (I²  = 0%). Among patients without known CVD, the incidence of MACE was lower (1·7 vs 3·9%), and the effect of a liberal strategy on MACE [0·79, (0·39-1·58)] was smaller and non-significant but not different from CVD patients (P = 0·30). Combining all CVD and non-CVD patients, a liberal strategy decreased MACE [0·59, (0·39-0·91); P = 0·02]. Conversely, among studies reporting mortality, a liberal strategy decreased mortality in CVD patients (11·7% vs·13·3%) but increased mortality (19·2% vs 18·0%) in patients without known CVD [interaction P = 0·05; ratio of RR 0·73, (0·53-1·00)]. A liberal strategy also did not benefit patients undergoing cardiac surgery; data were insufficient for percutaneous cardiac procedures.

CONCLUSIONS

In patients hospitalised for non-cardiac indications, liberal transfusion strategies are associated with a decreased risk of MACE in both those with and without known CVD. However, this only provides a survival benefit to CVD patients not admitted for CVD-corrective procedures.

Transfusion of recently donated (fresh) red blood cells (RBCs) does not improve survival in comparison with current practice, while safety of the oldest stored units is yet to be established: a meta-analysis

BACKGROUND AND OBJECTIVES

Preclinical studies generated the hypothesis that older stored red blood cells (RBCs) can increase transfusion risks. To examine the most updated and complete clinical evidence and compare results between two trial designs, we assessed both observational studies and randomized controlled trials (RCTs) studying the effect of RBC storage age on mortality.

MATERIALS AND METHODS

Five databases were searched through December 2014 for studies comparing mortality using transfused RBCs having longer and shorter storage times.

RESULTS

Analysis of six RCTs found no significant differences in survival comparing current practice (average storage age of 2 to 3 weeks) to transfusion of 1- to 10-day-old RBCs (OR 0·91, 95% CI 0·77-1·07). RBC storage age was lower in RCTs vs. observational studies (P = 0·01). The 31 observational studies found an increased risk of death (OR 1·13, 95% CI 1·03-1·24) (P = 0·01) with increasing age of RBCs, a different mortality effect than RCTs (P = 0·02).

CONCLUSION

RCTs established that transfusion of 1- to 10-day-old stored RBCs is not superior to current practice. The apparent discrepancy in mortality between analyses of RCTs and observational studies may in part relate to differences in hypotheses tested and ages of stored RBCs studied. Further trials investigating 1- to 10-day-old stored RBC benefits would seem of lower priority than studies to determine whether 4- to 6-week stored units have safety and efficacy equivalent to the 2- to 3-week-old stored RBCs commonly transfused today.

Red blood cell transfusion in the treatment and management of anaemia: the search for the elusive transfusion trigger

Therapeutic red blood cell (RBC) transfusion is widely utilized in the management of anaemia. Critically ill intensive care unit (ICU) patients in particular, as well as medical and haematology-oncology patients, are among the largest groups of users of RBC products. While anaemia is common in these patients, its treatment and management, including appropriate thresholds for RBC transfusion, remain controversial. We review here the function of RBCs in oxygen transport and physiology, with a view to their role in supporting and maintaining systemic tissue oxygenation. Adaptive and physiological compensatory mechanisms in the setting of anaemia are discussed, along with the limits of compensation. Finally, data from clinical studies will be examined in search of evidence for, or against, a clinically relevant transfusion trigger.

Epidemiology of thrombocytopenia in HIV inlection

Thrombocytopenia is a known complication of human immunodeficiency virus Type-1 (HIV-1) infection, and more data need to be collected on its frequency, severity, and clinical sequelae. We determined the frequency of thrombocytopenia and its relationship to other HIV infection characteristics from a review of records of 1004 HIV-infected patients attending two outpatient clinics in Washington, D.C. The self-reported sources of HIV-1 exposure were male homosexual activity (68%), bisexual activity (10%), heterosexual activity (6%), and intravenous drug use (15%). Fifty-nine percent of the individuals were white, 37% were black and 94% were male. Fifteen percent had AIDS. Thrombocytopenia occurred more frequently in subjects with AIDS (21.2%) than in HIV-infected individuals who did not fit clinical criteria for AIDS (9.2%) (p less than 0.001). Patients with few CD4-positive cells and an advanced stage of disease were more likely to have low platelet counts: 30% with an absolute CD4 cell count lower than 200/mm3 vs 8% with CD4 counts between 200 and 500 (p less than 0.00001), and 18.5% with Stage IV disease compared to 7.6% in Stage II (p less than 0.001) had platelet counts less than 150,000/mm3. Thrombocytopenia was more frequent in white males and older subjects. Although subjects infected by heterosexual exposure had a lower frequency of thrombocytopenia, intravenous drug users and homosexual men exhibited similar frequencies of thrombocytopenia. Of all subjects with platelet counts less than 50,000/mm3, 40% reported bleeding and 1 died of an intracranial hemorrhage. Thrombocytopenia occurs frequently in HIV-infected people, primarily in those with AIDS, low CD4 cell numbers, and advanced stages of diseases.

Pathogen-reduction methods: advantages and limits

Pathogen‐reduction (inactivation) provides a proactive approach to reducing transfusion‐transmitted infection. Pathogen‐reduction technologies have been successfully implemented by plasma fractionators resulting in no transmission of human immunodeficiency, hepatitis C, or hepatitis B viruses by US‐licensed plasma derivatives since 1987. Fractionation technologies cannot be used to treat cellular blood components. Although blood donor screening, deferral and disease testing have drastically reduced the incidence of transfusion‐transmitted diseases, the threat of new or re‐emerging pathogens remains. Of particular concern is the silent emergence of a new agent with a prolonged latent period in which asymptomatic infected carriers would donate and spread infection. The ultimate goal of pathogen‐inactivation is to reduce transmission of potential pathogens without significantly compromising the therapeutic efficacy of the cellular and protein constituents of blood. The acceptable technology must not introduce toxicities into the blood supply nor result in neoantigen formation and subsequent antibody production. Several promising pathogen‐inactivation technologies are being developed and tested, and others are currently in use, but all of them have limits. Pathogen‐reduction promises an additional ‘layer of protection’ from infectious agents and has the potential to impact the safety of blood transfusions worldwide.

Patient-specific transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is one of the leading causes of transfusion-associated mortality. The inadvertent transfusion of neutrophil antibodies can cause pulmonary transfusion reactions and TRALI. However, not all patients transfused with neutrophil antibodies experience transfusion reactions. A 22-year-old man with severe aplastic anaemia (SAA) experienced TRALI after a platelet transfusion. The donor was found to be alloimmunized to human neutrophil antigen (HNA)-3a, an antigen expressed by neutrophils from approximately 90% of Caucasians. Eleven other platelet components from this donor were transfused prior to this event and two caused reactions: one chills and one TRALI. Both episodes of TRALI occurred in the same male patient with SAA. The fact that one patient experienced TRALI following both exposures to anti-HNA-3a from the same donor whereas nine other recipients did not adds evidence to the observation that patient factors make a significant contribution to neutrophil antibody-mediated transfusion reactions.

A preliminary comparison of the prevalence of transfusion reactions in recipients of platelet components from donors with and without human leucocyte antigen antibodies

BACKGROUND

Human leucocyte antigen (HLA) antibodies have been implicated in transfusion-related acute lung injury, but the probability that the transfusion of a blood component containing HLA antibodies will cause a reaction is not known. This study compared the prevalence of reactions associated with the transfusion of platelet components with and without HLA antibodies.

STUDY DESIGN AND METHODS

This retrospective study tested 96 consecutive apheresis platelet donors for HLA class I and II antibodies. Matched control donors without HLA antibodies were selected and records were reviewed to determine the proportion of components from each group that caused reactions. In addition, all apheresis platelet donors involved with two or more reactions were identified and tested for HLA class I antibodies.

RESULTS

Five of the 96 donors had antibodies to class I or class II antigens and, of these, four had components transfused. The prevalence of reactions to components from these four donors with HLA antibodies and the 12 matched control donors without antibodies was similar (three reactions to 167 transfusions or 1.8% vs. three to 295 or 1.0%, respectively, P = 0.32). A retrospective review of the transfusion records from all platelet donors found that components from 22 caused two or more reactions and three (13.6%) had antibodies to HLA class I compared to 4.2% of the consecutively selected donors (P = 0.12). None of the patients experienced transfusion-related acute lung injury.

CONCLUSION

Reactions associated with transfusion of apheresis platelets containing HLA antibodies are unusual.

Pathogen inactivation technology: cleansing the blood supply

The calculated residual infectious risk of HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) from blood transfusion is extremely low. However, the risk of bacterial contamination remains and a variety of other agents including emerging viruses, protozoa and tick-borne agents threaten blood supplies and undermine public confidence in blood safety. Traditional methods of donor screening and testing have limited ability to further reduce disease transmission and cannot prevent an emerging infectious agent from entering the blood supply. Pathogen inactivation technologies have all but eliminated the infectious risks of plasma-derived protein fractions, but as yet no technique has proved sufficiently safe and effective for traditional blood components. Half-way technologies can reduce the risk of pathogen transmission from fresh frozen plasma and cryoprecipitate. Traditional methods of mechanical removal such as washing and filtration have limited success in reducing the risk of cell-associated agents, but methods aimed at sterilizing blood have either proved toxic to the cells or to the recipients of blood components. Several promising methods that target pathogen nucleic acid have recently entered clinical testing.

Blood substitutes: how close to a solution?

The term "blood substitute" is commonly misused when "red cell substitute (RCS) is meant. The ideal RCS should deliver (i) oxygen; (ii) require no compatibility testing; (iii) cause few side effects; (iv) have prolonged storage qualities; (v) persist in the circulation and (vi) be available at reasonable cost. While no drug with all these qualities is on the near horizon, several early generation RCS are approaching submission for licensing, at least for limited indications. Haemoglobin-derived RCS from human, bovine and recombinant sources, as well as perfluorochemicals that dissolve 02 are in different stages of development. While each formulation has its own physical characteristics, biological activities, and adverse reaction profile, all share one characteristic: the physiological consequences of delivering 02 with small molecules is poorly understood and may both account for problems seen in the clinical trials and provide therapeutic opportunities for the cancer patient. Those RCS in phase III trials all have a half-life measured in hours and are unlikely to replace transfusions or drugs that stimulate erythropoiesis for chronic anaemia, but they may play a role (i) in military and civilian trauma as resuscitation solutions, (ii) as a bridge to transfusion when no compatible blood is immediately available, (iii) as an adjunct to the autologous haemodilution management of surgery, or even (iv) in radiation therapy or the management of cancer-related vascular occlusive syndromes.

Association of highly active antiretroviral therapy failure with chemokine receptor 5 wild type

OBJECTIVES

Approximately 10% of HIV-infected patients fail to respond properly to highly active antiretroviral therapy (HAART). Among other factors, genetic variants of chemokine receptors have been shown to modify the course and outcome of HIV infection. Our objective was to investigate whether a failure of virological response is associated with polymorphisms of the chemokine receptors or cofactors.

METHODS

A total of 256 HIV-infected patients receiving HAART and 221 healthy controls were analysed for the chemokine receptor 5 (CCR5)-Delta32-bp, stromal derived factor 1 (SDF1)-3'A and chemokine receptor 2 (CCR2)-64I polymorphisms. Treatment failure was defined as failure to lower the viral load below 50 HIV-1 RNA copies/mL within the first year of treatment despite good adherence. Genomic DNA was extracted from peripheral blood lymphocytes (PBL) and amplified by polymerase chain reaction (PCR).

RESULTS

Successful treatment was associated with heterozygosity for the CCR5-Delta32-bp variant found in 24 of 184 responders (13%) vs. one of 72 nonresponders (1.4%; P=0.004). Eighty-four of 184 responders (45.7%) vs. 25 of 72 nonresponders (34.7%) were heterozygous for the SDF1-3'A allele (P=0.073). The CCR2-64I polymorphism was rare in both groups: 4.9% in responders vs. 1.4% in nonresponders (P=0.175). The odds ratio for successful treatment was 4.7 for individuals who tested positive for at least one variant allele of the three polymorphisms. Comparison of genotype frequencies between HIV-infected and healthy individuals showed highly significant differences (P<0.001).

CONCLUSIONS

Chemokine receptor polymorphisms have a modifying effect on the virological response to HAART. Multivariate analysis demonstrated that heterozygosity for the CCR5-Delta32-bp variant is an independent prognostic factor for treatment outcome.

Preserving the national blood supply

This paper examines the current state of the blood supply in the US and focuses on the potential for augmenting blood availability by attention to the iron status of donors. Increasing demands are being made upon the national blood supply as rates of blood donation are declining, in part because of the loss of blood donors as a result of enhanced screening and testing procedures. Iron-related means of expanding the blood supply include the use of blood from individuals undergoing therapeutic phlebotomy for hereditary hemochromatosis and enhancing the retention and commitment of women of childbearing age as donors by using iron supplementation to prevent iron deficiency. In Section I, Dr. Klein discuss the circumstances responsible for a decline in the population of eligible donors, including public attitudes toward donation, factors influencing the retention of donors by blood centers, and the effects of increased screening and testing to maintain the safety of the blood supply. In Section II, Drs. Kushner and Ajioka focus on the consequences of the decision by the US Food and Drug Administration (FDA) to develop recommendations to permit blood centers to collect blood from patients with hereditary hemochromatosis and to distribute this blood obtained without disease labeling if all other screening and testing procedures are passed. After summarizing the pathophysiology of hereditary hemochromatosis, the use by blood centers of blood obtained from heterozygotes and homozygotes for hereditary hemochromatosis is considered. In Section III, Dr. Brittenham reviews the use of low dose, short-term carbonyl iron supplementation for women donors of childbearing age. Replacing the iron lost at donation can help prevent iron deficiency in women of childbearing age and, by decreasing deferral, enhance the retention and commitment of women who give blood regularly. He emphasizes the use by blood centers of iron-related means to enhance recruitment and retention of blood donors.

Autoantibody formation in the alloimmunized red blood cell recipient: clinical and laboratory implications

Alloimmunization to erythrocyte antigens is a well-characterized complication in heavily transfused patients. Less well recognized, however, is the frequency of autoantibody formation in these previously alloimmunized patients. The autoantibodies are heterogeneous and of variable clinical significance. We describe the clinical history, laboratory evaluation, diagnosis, and treatment in 4 patients who developed autoantibodies in temporal association with alloantibody formation. In one case, the autoantibody found on routine screening had no clinical significance. In another case, the autoantibody made accurate blood typing and subsequent transfusion exceedingly difficult. Two patients experienced hemolysis as a consequence of the autoantibody. The management of both patients included supportive measures, while one patient required glucocorticosteroids and red blood cell transfusion. We review the published literature concerning autoimmunization in the transfused alloimmunized host. The spectrum of clinical consequences is important for the general practitioner to recognize, as these complications may occur during routine blood transfusions.

Intravenous Rh immune globulin prevents alloimmunization in D- granulocyte recipients but obscures the detection of an allo-anti-K

Rh immune globulin (RhIG) has been used to prevent alloimmunization in D(-) recipients of apheresis platelet transfusions from D(+) donors that may contain up to 5 mL of D(+) red blood cells (RBCs). Granulocyte concentrates contain approximately 30 mL of RBCs and it has been necessary to give D(-) recipients granulocyte transfusions from D(+) donors. Intravenous RhIG has not yet been demonstrated to be effective in preventing D alloimmunization with granulocyte transfusions. Four D(-) recipients received multiple D(+) granulocyte transfusions from D(+) donors and multiple injections of intravenous RhIG at a standard dose of 600 microg for each D(+) transfusion. Two D(-) males with chronic granulomatous disease were given 32 and 13 daily granulocyte transfusions, 18 and 2 of which, respectively, were D(+). After the first dose of intravenous RhIG, both patients exhibited circulating anti-D that was undetectable 3 to 4 years later. Two patients with severe aplastic anemia were given 5 and 14 granulocyte transfusions, 4 and 7 of which, respectively, were D(+). Both patients died before the effectiveness of RhIG could be assessed. In one of these patients the indirect and direct antiglobulin tests became positive after the first dose of intravenous RhIG, which required that subsequent granulocyte transfusions from D(+) donors be crossmatched by immediate spin (IS) testing only. A delayed hemolytic reaction attributed to allo-anti-K occurred after granulocytes from a K(+) donor were given to this patient. These results suggest that intravenous RhIG can be used to prevent alloimmunization to D in D(-) patients receiving large quantities of RBCs from D(+) granulocyte transfusions. However, anti-D and other passive antibodies from RhIG prohibit the use of the antiglobulin crossmatch with antigen-positive granulocyte donor samples. It may be important to frequently collect new samples to screen for newly formed allo-antibodies when IS crossmatches are used in place of the antiglobulin crossmatch.

From leukocyte reduction to leukocyte transfusion: the immunological effects of transfused leukocytes

In transfusion medicine, mononuclear leukocytes have been studied more often as contaminants of red blood cells or platelets responsible for adverse transfusion outcomes than as therapeutic cells; leukocyte transfusion has been effective in augmenting recipient immunity only in limited clinical situations. Studies in leukocyte reduction and leukocyte transfusion have progressed separately as if the leukocytes' adverse and therapeutic effects result from different immunological mechanisms. With growing clinical experience, however, it is increasingly clear that some adverse immune effects may be exploited for therapeutic benefit. Advances in clinical immunology, understanding of the variety of cells and functions in the leukocyte fraction of blood, and blood component preparation technology may lead to new ways of deriving immunological benefit from transfused blood leukocytes while minimizing their adverse effects. This chapter reviews the current uses of leukocyte reduction and mononuclear leukocyte transfusion, with an emphasis on the relationship between transfusion-associated graft-versus-host disease and donor lymphocyte infusion in controlling relapsed leukaemias.

Trypanosoma cruzi meningoencephalitis in HIV-infected patients

Five cases of Trypanosoma cruzi meningoencephalitis in HIV-infected patients are reported. All patients presented with mass lesions on head computed tomographic scan, trypanosomes in the cerebrospinal fluid and failure to respond to antitoxoplasmosis therapy. Benznidazole therapy was associated with clinical improvement in 1 patient. Another 4 patients had T cruzi identified in a peripheral smear. T cruzi needs to be considered in the differential diagnosis of HIV-infected patients with central nervous system mass lesions if they have a history of appropriate exposure.

Cationic amino acid transporter mRNA expression in rat kidney and liver

Expression of rat cationic amino acid transporter 2 (r-CAT-2) mRNA was studied in kidney and liver using Northern blot analysis and nonradioactive in situ hybridization with a probe identifying both the r-CAT-2alpha and -2beta splice variants. Expression of r-CAT-2 mRNA was higher in the liver than in the kidney. Within the kidney, r-CAT-2 mRNA was more abundant in the outer and inner medulla than in the cortex. In the liver lobule, the intensity of the hybridization signal in hepatocytes decreased between the portal area and the central vein. In the kidney, hybridization signals were detected in parietal cells of Bowman's capsule, various tubule cells of outer and inner medulla, in endothelial and interstitial cells of inner medulla, and in papillary epithelial cells.

Peripheral expansion of pre-existing mature T cells is an important means of CD4+ T-cell regeneration HIV-infected adults

The CD4+ T-cell pool in HIV-infected patients is in a constant state of flux as CD4+ T cells are infected and destroyed by HIV and new cells take their place. To study T-cell survival, we adoptively transferred peripheral blood lymphocytes transduced with the neomycin phosphotransferase gene between syngeneic twin pairs discordant for HIV infection. A stable fraction of marked CD4+ T cells persisted in the circulation for four to eighteen weeks after transfer in all patients. After this time there was a precipitous decline in marked cells in three of the patients. At approximately six months, marked cells were in lymphoid tissues in proportions comparable to those found in peripheral blood. In two patients, the proportion of total signal for the transgene (found by PCR analysis) in the CD4/CD45RA+ T-cell population relative to the CD4/CD45RO+ population increased in the weeks after cell infusion. These findings indicate that genetically-marked CD4+ T cells persist in vivo for weeks to months and that the CD4+ T-cell pool in adults is maintained mostly by the division of mature T cells rather than by differentiation of prethymic stem cells. Thus, after elements of the T-cell repertoire are lost through HIV infection, they may be difficult to replace.

Long-term prognosis of surgically-treated aortic aneurysms and dissections in patients with and without Marfan syndrome

OBJECTIVE

Aortic aneurysms and dissections are the leading causes of premature death in Marfan syndrome (MfS). This study aims to compare long-term results of surgically treated aortic aneurysms and dissections in patients with and without MfS in respect to early and late prognosis.

METHODS

From March 1975 to August 1994, 33 patients with classic MfS (group A, age 34.2 +/- 9 years) and 298 patients with non-fibrillinopathic aortic disease (group B, age 54 +/- 13 years) underwent aortic surgery. Acute dissections occurred in 57.6 (A) versus 37.9% (B). A total of 54.6% of patients in group A were treated with a composite graft versus 16.4% in B. The aortic arch and the descending aorta was replaced in 30.4% of MfS patients and 24.9% of patients without MfS.

RESULTS

We observed 7 (25.0%, A) versus 35 (14.2%, B) late deaths among the 28 (A) versus 247 (B) early survivors. In 5 patients (17.9%) of A and 8 patients (3.2%) of B, late death was caused by redissection or recurrent aneurysm (P < 0.001). Long-term survival after 5, 10 and 15 years in group A was 82 +/- 7, 60 +/- 11 and 30 +/- 22%, and 75 +/- 3, 69 +/- 3 and 64 +/- 4% in group B. A total of 22 reoperations were performed in 11 MfS patients, 17 reoperations were due to recurrent aortic diseases. Three of the 8 patients underwent reoperation after Wheat procedure because of sinus valsalva aneurysm. None of the patients with composite graft replacement needed reoperation in this segment, but 3 patients suffered from redissection at the proximal aortic arch. In group B, reoperations were significantly less frequent (10.7%) compared to MfS patients (66.7%; P < 0.001).

CONCLUSIONS

Surgical treatment of aortic disease in MfS patients is associated with a high risk of redissection and recurrent aneurysm. If the ascending aorta needs to be replaced, we recommend the composite graft technique and a more aggressive approach to reduce the frequency of distal reoperations. In order to reduce the high reoperation rate in MfS patients, frequent clinical follow-up may contribute to improve life expectancy in MfS patients.

Marfan Database (third edition): new mutations and new routines for the software

The Marfan database is a software that contains routines for the analysis of mutations identified in the FBN1 gene that encodes fibrillin-1. Mutations in this gene are associated not only with Marfan syndrome but also with a spectrum of overlapping disorders. The third version of the Marfan database contains 137 entries. The software has been modified to accommodate four new routines and is now accessible on the World Wide Web at http://www.umd.necker.fr

A novel mutation in the neonatal region of the fibrillin (FBN)1 gene associated with a classical phenotype of Marfan syndrome (MfS). Mutations in brief no. 163. Online

Marfan Syndrome (MfS) is an autosomal dominant inherited connective tissue disorder with variable phenotypic expression of cardiovascular, skeletal and ocular manifestations. Cardiovascular complications, such as aortic aneurysm and dissection drastically reduce life expectancy of individuals with MfS, whereas preventive surgery substantially improves the prognosis of these patients. A number of mutations in the fibrillin 1 (FBN1) gene associated with MfS have been identified to date, demonstrating considerable molecular heterogeneity. One region, however, located around exon 24, exhibits a striking clustering of mutations, which are associated with a severe, socalled neonatal form of MfS. Here we report the first mutation (G2950A) in exon 24 of the neonatal region of the FBN1 gene, associated with a classic MfS phenotype. The mutation leads to the subsitution of valin by isoleucin (V984I), both uncharged amino acids, which only differ in a single methyl group. This defect was identified in a proband with cardiovascular manifestations of MfS by SSCP analysis of PCR-amplified genomic DNA, direct PCR sequencing and RFLP analysis. The substitution was neither detected in the unaffected 4-year old daughter of the proband, nor in 3 of his healthy family members nor in 108 allels from control individuals, suggesting that this mutation is causative for MfS in the patient. Since no other family member of the proband is affected by MfS, the defect described is sporadic. In summary, we identified a novel defect in exon 24 of the neonatal region of the FBN1 gene in a patient with a classic phenotype of MfS, suggesting that conservative substitutions in this region may lead to a less severe phenotype of the disease. This finding further demonstrates the remarkable phenotypic heterogeneity associated with FBN1 mutations and stresses the significance of modifying genes and individual alterations in protein function for the pheontypic expression of the disease.

Enumeration of CD34+ hematopoietic progenitor cells in peripheral blood and leukapheresis products by microvolume fluorimetry: a comparison with flow cytometry

There is increasing interest in both standardization and simplification of methods for enumeration of CD34+ hematopoietic progenitor cells (HPC) to facilitate cellular therapies and to improve interinstitutional comparison of clinical and laboratory results. We evaluated a novel method for CD34+ cell enumeration based on microvolume fluorimetry (MVF) compared with our laboratory's routine flow cytometric method on samples of peripheral blood and leukapheresis products. The MVF method is semiautomated and uses a 633-nm light from a helium-neon laser to scan fluorochrome-labeled cells held in stasis in a capillary known volume. The performance of the MVF assay for enumeration of CD34+ cells was found to be comparable to our routine flow cytometric assay in linearity and accuracy in the range of 5-1500 cells per microliter. Precision of MVF for replicate assays on the same instrument was demonstrated by coefficient of variation (CV) values of 8.4% at a CD34+ cell concentration of 284/microliters for a sample volume of 0.8 microliters, and 15.7% at 12/microliters for a sample volume of 3.2 microliter. Precision among three different instruments was demonstrated, using sample volumes of 1.6 microliters, by CV values of 44% at 6 cells/microliters and 4.6% at 733 cells/microliters. In a field sample evaluation, precision of the entire assay system for paired measurements on 0.8-microliter sample volumes was demonstrated by CV values of 50%, 31%, and 15% for peripheral blood samples with concentrations of 0-10, 10-20, and 20-100 CD34+ cells/microliters, respectively, and 6.3%, 8.1% and 6.5% for leukapheresis samples with concentrations of 0-100, 100-1,000, and 1,000-2,500 CD34+ cells/microliters, respectively. The MVF assay was easy to perform, required minimal technical training time, and had a turnaround time of 40 min, of which less than 10 min was actual technical time. These observations suggest that the MVF method for CD34+ cell enumeration may prove useful to clinical laboratories providing support for HPC collection, processing, and transplantation services that require relatively simple, rapid assays for product quality control or to guide real-time clinical decisions.

Growth factors and their impact on transfusion medicine

Hematopoietic growth factors, glycoproteins that stimulate self-renewal, differentiation, and proliferation of responsive hematopoietic cells, promise to revolutionize transfusion medicine. Recombinant DNA technology has made several of these cytokines available at pharmacologic doses, and new candidate agents for clinical application appear regularly. Growth factors prescribed for patients have already reduced the requirement for red blood cell and granulocyte transfusions in selected clinical circumstances. A lineage-specific thrombopoietin will likely limit the need for platelet transfusions. Hematopoietic cytokine injections have also been used to increase the number of red blood cells, granulocytes and circulating primitive progenitor cells in blood donors. Cytokine-stimulated peripheral blood progenitor cell infusions have complemented and, in some instances, replaced bone marrow for adjunctive cancer chemotherapy and for bone marrow transplantation. Finally, synergistic combinations of cytokines can effect ex vivo expansion of lymphocytes and of progenitor cells to provide novel blood components. Hematopoietic growth factors are still expensive and their long-term effects remain to be determined. However, as the biologic activities of cytokines and the physiology of hematopoietic progenitor cells become better understood, the clinical application of novel cellular components may redefine the concept of blood transfusion.

Comparison of random-donor platelet concentrates prepared from whole blood units and platelets prepared from single-donor apheresis collections

BACKGROUND

The use of fresh platelets results in better posttransfusion recovery and survival than does the use of platelets that have been stored before transfusion. Activation of platelets during preparation and storage may be one of the factors responsible for a number of storage-related changes in platelet membrane proteins. Blood centers commonly prepare platelet concentrates from both multiple units of whole blood and single-donor plateletpheresis collections.

STUDY DESIGN AND METHODS

Seventeen plateletpheresis concentrates, anticoagulated with ACD, were compared to platelets prepared from whole blood from the same donor that was anticoagulated with CPDA-1 (random-donor platelets). After preparation, plateletpheresis and random-donor platelets were stored in plastic storage bags at 22 degrees C for 5 days. Platelet surface glycoproteins were examined by flow cytometry after platelets were fixed in dilute plasma with 1-percent formaldehyde and stained with fluorescein isothiocyanate-labeled monoclonal antibodies CD42b (anti-glycoprotein [GP]lb), CD41a (anti-GPllb/llla), and CD62 (anti-P-selectin).

RESULTS

The binding of anti-CD42b was greater in plateletpheresis concentrates than in random-donor platelets on Days 3 and 5 (p < 0.01) of storage; binding of anti-CD62 was greater in the random-donor concentrates (p < 0.01) on Days 3 and 5. Plateletpheresis concentrate aggregation responses were greater on Day 5 (p < 0.01). To determine if the type of anticoagulant and the method of mixture with blood contributed to these changes, 10 samples were split into aliquots and prepared in two separate ways: One group of samples was prepared by allowing anticoagulant (ACD) and blood to flow into the tube at a rate of 3 microL per second, and the other group of samples was prepared by allowing blood to flow into tubes containing a measured amount of CPDA-1. The first samples bound more anti-CD42b than the second samples (p < 0.01). The second group of samples contained significantly more microvesicles that bound anti-CD41a than did the first group (p < 0.01). Samples prepared by the first method but anticoagulated with CPDA-1 contained more microvesicles but had the same amount of anti-CD42b binding as did similarly prepared samples anticoagulated with ACD (p < 0.05).

CONCLUSION

Platelet concentrates prepared from single units of whole blood and anticoagulated with CPDA-1 bind less anti-CD42b and more anti-CD62 than do platelets obtained by apheresis. These differences may be attributed to platelet sedimentation and the transient exposure of some of the platelets in the blood that is first collected during whole-blood donation to high concentrations of anticoagulant.