A comparative study of two routinely used protocols for ex vivo erythroid differentiation.

BACKGROUND: Erythropoiesis is a complex developmental process in which a hematopoietic stem cell undergoes serial divisions and differentiates through well-defined stages to give rise to red blood cells. Over the last decades, several protocols have been developed to perform ex vivo erythroid differentiation, allowing investigation into erythropoiesis and red cell production in health and disease. RESULTS: In the current study, we compared the two commonly used protocols by assessing the differentiation kinetics, synchronisation, and cellular yield, using molecular and cellular approaches. Peripheral blood CD34+ cells were cultured in a two-phase (2P) or a four-phase (4P) liquid culture (LC) and monitored for 20 days. Both protocols could recapitulate all stages of erythropoiesis and generate reticulocytes, although to different extents. Higher proliferation and viability rates were achieved in the 4P-LC, with a higher degree of terminal differentiation and enucleation, associated with higher levels of the erythroid-specific transcription factors GATA-1, KLF-1, and TAL-1. Although the 2P-LC protocol was less efficient regarding terminal erythroid differentiation and maturation, it showed a higher yield of erythroid progenitors in the erythropoietin (EPO)-free expansion phase. CONCLUSIONS: We provide data supporting the use of one protocol or the other to study the biological processes occurring in the early or late stages of erythroid differentiation, depending on the physiological process or pathological defect under investigation in a given study.

Access to care for aging former workers living in an immigrant hostel / Accès aux soins d'une population d'anciens travailleurs immigrés vivant en foyer

The Chibanis represent the population of aging former immigrant workers who arrived in France in the 1970s in order to take up employment. Most of them still live in immigrant hostels, which are not appropriate for an older population. This anthropological study was conducted on Chibanis living in an immigrant hostel in the 15th arrondissement of Marseille. The objectives were to assess the medical, economic, and social characteristics of this population, to understand their access to health care, and to measure their adherence to the prevention actions of an association. 67 Chibanis aged 65 and over were included, with a median age of 77: 91% had access to a general practitioner, and 86.6% had more than two chronic diseases. More than half of the Chibanis complained of dental problems, and 20% complained of ophthalmological problems. Only 32.8% of the Chibanis included agreed to follow-up care with the nurses from the association. The population of Chibanis are isolated geographically from their families, live in poor socio-economic conditions, and often have insufficient medico-social coverage. They must "manage" their chronic diseases, as well as costly health problems such as dental or ophthalmic diseases. Improving care pathways for this population requires us to identify their specificities and all the factors hindering prevention actions.

Les Chibanis ­ "cheveux blancs" en arabe dialectal ­ désignent les anciens travailleurs immigrés arrivés en France dans les années 1970 pour exercer un emploi. Ils vivent encore pour la plupart au sein de foyers construits pour des hommes seuls exerçant une profession et non pour accueillir des hommes en situation de vieillissement. Notre travail anthropologique s'est organisé autour d'une population de Chibanis, vivant dans un foyer dans le 15e arrondissement de Marseille. Les objectifs étaient de mieux connaître cette population d'un point de vue médico-socio-culturel, de connaître les modalités de leur accès aux soins et enfin de connaître leur adhésion aux actions de prévention d'une association. 67 Chibanis ≥65 ans ont été inclus, avec une médiane de l'âge de 77 ans : 91 % déclaraient avoir un médecin traitant, 86,6 % avaient plus de 2 maladies chroniques. Plus de la moitié des Chibanis souffraient de problèmes dentaires et près de 20 % présentaient des problèmes ophtalmologiques. Seuls 32,8 % des Chibanis inclus ont accepté de réaliser un suivi par les infirmiers. La population des Chibanis, isolée géographiquement de leur famille, économiquement précaire et avec une couverture médico-sociale souvent insuffisante, doit « gérer ¼ ses pathologies chroniques, et des problèmes de santé notamment dentaires et ophtalmiques couteux. L'amélioration de leurs parcours de santé nécessite de mieux comprendre leurs spécificités et les divers facteurs qui peuvent entraver les actions de prévention.

Comparison of HLA antibody identification methods for the selection of platelet products for HLA-mediated platelet refractory patients.

In an ineffective transfusion context, solid-phase immunoassays using the Luminex platform for the detection and characterization of HLA antibodies are currently used to select HLA-compatible platelet products. A new HLA antibody identification method, the HISTO SPOT® HLA AB test (BAG Health care GmbH, Lich, Germany), based on the detection of antibodies directed against a recombinant single antigen (SA) by colored spots detected by HISTO MATCH HLA AB module software, runs fully automated on the MR.SPOT®. The aim of this study was to compare the ability of the HISTO SPOT HLA AB and C1qScreen™ (C1q SAB) assays with that of the Labscreen single antigen class I (OL SAB) assay to detect anti-HLA class I antibodies in 56 serum samples from 54 platelet refractory acute myeloid leukemia patients who received HLA mismatch platelet concentrates at a single oncohematology center. In total, 1414 class I specificities, 433 HLA-A and 981 HLA-B, were detected by the OL SAB test. The mean fluorescence intensity (MFI) was >5000 for 874 antigens and <5000 for 655 antigens. The HISTO SPOT® HLA AB and C1q SAB tests identified 85% and 79% of OL SA-detected antigens with an MFI >5000, respectively, but did not identify 34% and 44% of OL SAB-detected antigens, highlighting the lower sensitivity of these techniques. Interestingly, the donor-specific antibodies (DSAs) identified by the HISTO SPOT® HLA AB and C1q SAB assays reacted against HLA mismatch platelet concentrates with the same specificity (86%) and positive predictive (77%) value as in the OL SAB test when the MFI threshold was >2000 for DSA detection. Although the HISTO SPOT® HLA AB test is less sensitive than the OL SAB test, this test could be used for the selection of HLA-compatible platelet products.

Low Prevalence of HLA-G Antibodies in Lung Transplant Patients Detected using MAIPA-Adapted Protocol.

Lung transplantation is often complicated by acute and/or chronic rejection leading to graft-function loss. In addition to the HLA donor-specific antibodies (HLA-DSA), a few autoantibodies are correlated with the occurrence of these complications. Recently, antibodies directed against non-classical HLA molecules, HLA-G, -E, and -F have been detected in autoimmune diseases, like systemic lupus erythematosus. Non-classical HLA molecules are crucial in the immunological acceptance of the lung graft, and some of their isoforms, like HLA-G*01:04 and -G*01:06, are associated with a negative clinical outcome. The aim of this study is to determine the frequency of detection of HLA-G antibodies in lung transplant recipients (LTRs) and their impact on the occurrence of clinical complications. After incubating the cell lines SPI-801, with and without three different HLA-G isoform expression, with sera from 90 healthy blood donors and 35 LTRs (before and after transplantation), HLA-G reactivity was revealed using reagents from commercial monoclonal antibody immobilization of platelet antigen assay (MAIPA ApDIA®). Only one serum from one blood donor had specific reactivity against the HLA-G transduced lines. Non-specific reactivity in many sera from LTRs was observed with transduced- and wild-type cell lines, which may suggest recognition of an autoantigen expressed by the SPI-801 cell line. In conclusion, this study allowed the development of a specific detection tool for non-denatured HLA-G antibodies. These antibodies seem uncommon, both in healthy subjects and in complicated LTRs. This study should be extended to patients suffering from autoimmune diseases as well as kidney and heart transplant recipients.

HLA-F and LILRB1 Genetic Polymorphisms Associated with Alloimmunisation in Sickle Cell Disease.

Red blood cell (RBC) transfusion remains a critical component in caring for the acute and chronic complications of sickle cell disease (SCD). Patient alloimmunisation is the main limitation of transfusion, which can worsen anaemia and lead to delayed haemolytic transfusion reaction or transfusion deadlock. Although biological risk factors have been identified for immunisation, patient alloimmunisation remains difficult to predict. We aimed to characterise genetic alloimmunisation factors to optimise the management of blood products compatible with extended antigen matching to ensure the self-sufficiency of labile blood products. Considering alloimmunisation in other clinical settings, like pregnancy and transplantation, many studies have shown that HLA Ib molecules (HLA-G, -E, and -F) are involved in tolerance mechanism; these molecules are ligands of immune effector cell receptors (LILRB1, LILRB2, and KIR3DS1). Genetic polymorphisms of these ligands and receptors have been linked to their expression levels and their influence on inflammatory and immune response modulation. Our hypothesis was that polymorphisms of HLA Ib genes and of their receptors are associated with alloimmunisation susceptibility in SCD patients. The alloimmunisation profile of thirty-seven adult SCD patients was analysed according to these genetic polymorphisms and transfusion history. Our results suggest that the alloimmunisation of SCD patients is linked to both HLA-F and LILRB1 genetic polymorphisms located in their regulatory region and associated with their protein expression level.

Characterization of the novel HLA-B*07:482 allele using next-generation sequencing methods.

HLA-B*07:482 differs from HLA-B*07:02:01:01 allele by one nucleotide substitution in codon 285 in exon 5.

HLA-F transcriptional and protein differential expression according to its genetic polymorphisms.

Many specificities single out HLA-F: its structure, expression regulation at cell membrane and function. HLA-F mRNA is detected in the most cell types and the protein is localized in the ER and Golgi apparatus. When expressed at cell surface, HLA-F may be associated to ß2-microglobulin and peptide or expressed as an open-conformer molecule. HLA-F reaches the membrane upon activation of different primary cell types and cell-lines. HLA-F has its highest affinity for the KIR3DS1-activating NK receptor, but also binds inhibitory immune receptors. Some studies reported that HLA-F expression is associated with its genotype. Higher HLA-F mRNA expression associated with F*01:01:02, and 3 noncoding SNPs, rs1362126, rs2523405, and rs2523393, located in HLA-F-AS1 or upstream the HLA-F sequence were associated with HLA-F mRNA expression. Given the implication of HLA-F in many clinical setting, and the undisclosed process of its expression regulation, we aim to confirm the effect of the aforementioned SNPs with HLA-F transcriptional and protein expression. We analyzed the distribution, frequency and linkage disequilibrium of these SNPs at worldwide scale in the 1000 Genomes Project samples. Influence on the genotype of each SNP on HLA-F expression was explored using RNAseq data from the 1000 Genomes Project, and using Q-PCR and intracellular cytometry in PBMC from healthy individuals. Our results show that the SNPs under studied displayed remarkably different allelic proportion according to geography and confirm that rs1362126, rs2523405, and rs2523393 displayed the most concordant results, with the highest effect size and a double-dose effect.

Clinical relevance of cell-free DNA quantification and qualification during the first month after lung transplantation.

Background: Many studies have reported the relevance of donor-derived cfDNA (dd-cfDNA) after lung transplantation (LTx) to diagnose and monitor acute rejection (AR) or chronic rejection or infection (INF). However, the analysis of cfDNA fragment size has not been studied. The aim of this study was to determine the clinical relevance of dd-cfDNA and cfDNA size profiles in events (AR and INF) during the first month after LTx. Methods: This prospective, single-center study includes 62 LTx recipients at the Marseille Nord Hospital, France. Total cfDNA quantification was performed by fluorimetry and digital PCR, dd-cfDNA by NGS (AlloSeq cfDNA-CareDX®), and the size profile by BIABooster (Adelis®). A bronchoalveolar lavage and transbronchial biopsies at D30 established the following groups: not-injured and injured graft (AR, INF, or AR+INF). Results: Quantification of total cfDNA was not correlated with the patient's status at D30. The percentage of dd-cfDNA was significantly higher for injured graft patients at D30 (p=0.0004). A threshold of 1.72% of dd-cfDNA correctly classified the not-injured graft patients (negative predictive value of 91.4%). Among recipients with dd-cfDNA >1.72%, the quantification of small sizes (80-120bp) >3.70% identified the INF with high performance (specificity and positive predictive value of 100%). Conclusion: With the aim of considering cfDNA as a polyvalent non-invasive biomarker in transplantation, an algorithm combining the quantification of dd-cfDNA and small sizes of DNA may significantly classify the different types of allograft injuries.

Evaluation of a new complement-dependent lymphocytotoxicity cross match method using an automated cell counter, the NucleoCounter® NC-3000™.

Complement-dependent lymphocytotoxicity cross match (CDC-XM) is the ultimate test of donor/recipient compatibility prior to organ transplantation. This test is based on cell viability, evaluated under fluorescence microscopy by an operator after proper staining. The determination of the positivity threshold may vary depending on the operator. We developed a new method in which the final step of determining cell viability is automated using the NC-3000™ (Chemometec®), an image cytometer able to precisely determine the percentage of dead/live cells in a suspension. After T and B donor cells isolation by negative selection, complement-dependent lysis was performed in macrovolumes in a PCR plate. Then, cell viability was measured by the NC-3000™. The sensitivity and routine CDC-XM results of this new method were compared to those of CDC-XM reference method using Terasaki plates. The sensitivity of CDC-XM expressed in the ASHI scoring system of this method was similar to the reference method results for a dilution range of the positive controls. Similarly, the results of the new method were comparable in a clinical situation to those obtained with the reference method after a study of 10 cross-matches, of which 5 cross-matches with DSA were positive and five cross-matches without DSA were negative. Moreover, ASHI scores were similar to those obtained using the reference method, and the mortality percentage was reproducible (CV < 15%). The assessment of cell viability by the NC-3000™ is easy to perform and highly reproducible but requires CDC-XM to be performed by the macrovolume method. The determination of a precise percentage of viability/mortality by the automation excludes operator variability and allows a better understanding of results close to the decision threshold.

Therapeutic efficacy of platelet transfusion treated with amotosalen/UVA pathogen inactivation technology (INTERCEPTTM Blood System) in acute myeloid leukemia patients undergoing chemotherapy with curative intent: a single center experience.

BACKGROUND: The INTERCEPTTM Blood System (Intercept Blood System, Cerus Europe BV, Amersfoort, the Netherlands) has been used to reduce or inactivate pathogen load in platelet concentrates in France for three years. MATERIALS AND METHODS: After comparing the transfusion efficiency between pathogen-reduced platelets (PR_PLT) and untreated platelet products (U_PLT), our single-center observational study assessed the effectiveness of PR_PLT for the prevention of bleeding and for therapeutic treatment of WHO grade 2 bleeding in 176 patients undergoing chemotherapy with curative intent for acute myeloid leukemia (AML). The main endpoints were the 24-hour (h) corrected count increment (24h_CCI) after each transfusion, and time to next transfusion. RESULTS: Whereas the transfused doses tended to be higher in the PR_PLT group compared to U_PLT, there was a significant difference in intertransfusion interval (ITI) and 24h_CCI. In prophylactic transfusions, PR_PLT transfusions of >0.65×1011/10 kg, regardless of the age of the product (day 2 to day 5), resulted in a 24h_CCI similar to that of the untreated platelet product; this meant the patient could be transfused at least every 48h. In contrast, most PR_PLT transfusions of <0.55×1011/10 kg did not achieve a transfusion interval of 48h. In the context of WHO grade 2 bleeding, PR_PLT transfusions >0.65×1011/10 kg and storage of less than 4 days seems more effective in stopping bleeding. DISCUSSION: These results, which must be confirmed by prospective studies, indicate the need for vigilance regarding the quantity and quality of PR_PLT products used to treat patients at risk of bleeding crisis. Future prospective studies are needed to confirm these findings.

New methods for the quantification of mixed chimerism in transplantation.

Background: Quantification of chimerism showing the proportion of the donor in a recipient is essential for the follow-up of hematopoietic stem cell transplantation but can also be useful to document an immune tolerance situation after solid organ transplantation. Historically, chimerism has been quantified from genomic DNA, but with technological advances, chimerism from donor-derived cell-free DNA seems particularly relevant in solid organ transplantation. Methods: The reference method was until recently the short tandem repeat technique, but new innovative techniques as digital PCR (dPCR) and NGS, have revolutionized the quantification of chimerism, such as the so-called microchimerism analysis. After a short review of chimerism methods, a comparison of chimerism quantification data for two new digital PCR systems (QIAcuity™ dPCR (Qiagen®) and QuantStudio Absolute Q (ThermoFisher®) and two NGS-based chimerism quantification methods (AlloSeq HCT™ (CareDx®) and NGStrack™ (GenDX®)) was performed. Results: These new methods were correlated and concordant to routinely methods (r²=0.9978 and r²=0.9974 for dPCR methods, r²=0.9978 and r²=0.9988 for NGS methods), and had similar high performance (sensitivity, reproductibility, linearity). Conclusion: Finally, the choice of the innovative method of chimerism within the laboratory does not depend on the analytical performances because they are similar but mainly on the amount of activity and the access to instruments and computer services.

Accès aux soins d'une population d'anciens travailleurs immigrés vivant en foyer.

The Chibanis represent the population of aging former immigrant workers who arrived in France in the 1970s in order to take up employment. Most of them still live in immigrant hostels, which are not appropriate for an older population. This anthropological study was conducted on Chibanis living in an immigrant hostel in the 15th arrondissement of Marseille. The objectives were to assess the medical, economic, and social characteristics of this population, to understand their access to health care, and to measure their adherence to the prevention actions of an association. 67 Chibanis aged 65 and over were included, with a median age of 77: 91% had access to a general practitioner, and 86.6% had more than two chronic diseases. More than half of the Chibanis complained of dental problems, and 20% complained of ophthalmological problems. Only 32.8% of the Chibanis included agreed to follow-up care with the nurses from the association. The population of Chibanis are isolated geographically from their families, live in poor socio-economic conditions, and often have insufficient medico-social coverage. They must "manage" their chronic diseases, as well as costly health problems such as dental or ophthalmic diseases. Improving care pathways for this population requires us to identify their specificities and all the factors hindering prevention actions.

Frequency and characterization of RHD and RHCE variants in the Noir Marron population from French Guiana.

BACKGROUND: The RH system is one of the most polymorphic blood group systems due to the proximity and opposite orientation of RHD and RHCE genes. Numerous alleles are described and can affect Rh protein expression. This complexity is especially evident in populations of African origin. We performed RHD and RHCE genotyping of the Noir Marron population in French Guiana. This population belongs to the Maroon community who are direct descendants of African slaves, who escaped from Dutch plantations, in the current day Suriname, during the 17th century. They represent an original ethnic group with highly blended culture. METHODS AND MATERIALS: A total of 89 DNA samples were collected from four different ethnic groups of the Noir Marron population of French Guiana. RHD and RHCE genotyping was performed using DNA microarray and/or sequencing. RESULTS AND DISCUSSION: Significant allelic diversity was shown, with 45% of individuals presenting an RHD gene variant (most common: RHD*DAU, RHD*DIVa, and RHD*DIIIa allele) and 9.4% with a partial D phenotype. Likewise, 85% presenting an RHCE gene variant and 9% a partial RH2 antigen. One original allele was identified in two D+ Noir Marron individuals: a hybrid RHD*DIIIa-CE(9)-D allele, encoding probably a partial D antigen and associated with an RHCE*ce(48C,733G,1006T) allele. The African diversity of RHD and RHCE genes is found in this population with preserved genetic but mixed cultural backgrounds. These data allow us to describe the characteristics of the RH system antigen and highlights a significant number of partial antigens with a risk of alloimmunization.

An overview of red blood cell and platelet alloimmunisation in transfusion.

Post-transfusion alloimmunisation is the main complication of all those observed after one or more transfusion episodes. Alloimmunisation is observed after the transfusion of red blood cell concentrates but also of platelet concentrates. Besides alloimmunisation due to antigens carried almost exclusively by red blood cells such as those of the Rhesus-Kell system, alloimmunisation often raises against HLA antigens; the main responsibility for that, apart from platelet transfusions, lies with residual leukocytes in the products transfused, hence the central importance of effective leukoreduction right from the blood product preparation stage. Alloimmunization is not restricted to transfusion, but it is also observed during pregnancies, carrying out microtransfusions of blood from the fetus immunizing the mother through the placenta (in a retrograde way). Preexisting maternal-fetal immunization can complicate a transfusion program and intensify the creation of alloantibodies in several blood and tissue group systems. The occurrence of autoantibodies, created by several pathogenic reasons, can also interfere with the propensity of certain recipients of blood components to produce alloantibodies. The genetic condition of individuals is in fact strongly linked to the ability or not to recognize antigenic variants foreign to their own biological program and mount an alloimmune response. Some hemoglobin diseases, in carriers of which transfusions can be iterative and lifelong, are complicated by frequent alloimmunizations and amplification of the complications of these alloimmunizations, imposing even stricter transfusion rules. This review details the mechanisms favoring the occurrence of alloimmunization and the immunological principles for the production of molecular and cellular tools for alloimmunization. It concludes with the main preventive measures available to limit the occurrence of these frequent complications of varying severity but sometimes severe.

Mobilisation of HLA-F on the surface of bronchial epithelial cells and platelets in asthmatic patients.

Uncontrolled inflammation of the airways in chronic obstructive lung diseases leads to exacerbation, accelerated lung dysfunction and respiratory insufficiency. Among these diseases, asthma affects 358 million people worldwide. Human bronchial epithelium cells (HBEC) express both anti-inflammatory and activating molecules, and their deregulated expression contribute to immune cell recruitment and activation, especially platelets (PLT) particularly involved in lung tissue inflammation in asthma context. Previous results supported that HLA-G dysregulation in lung tissue is associated with immune cell activation. We investigated here HLA-F expression, reported to be mobilised on immune cell surface upon activation and displaying its highest affinity for the KIR3DS1-activating NK receptor. We explored HLA-F transcriptional expression in HBEC; HLA-F total expression in PBMC and HBEC collected from healthy individuals at rest and upon chemical activation and HLA-F membrane expression in PBMC, HBEC and PLT collected from healthy individuals at rest and upon chemical activation. We compared HLA-F transcriptional expression in HBEC from healthy individuals and asthmatic patients and its surface expression in HBEC and PLT from healthy individuals and asthmatic patients. Our results support that HLA-F is expressed by HBEC and PLT under healthy physiological conditions and is retained in cytoplasm, barely expressed on the surface, as previously reported in immune cells. In both cell types, HLA-F reaches the surface in the inflammatory asthma context whereas no effect is observed at the transcriptional level. Our study suggests that HLA-F surface expression is a ubiquitous post-transcriptional process in activated cells. It may be of therapeutic interest in controlling lung inflammation.

Five-Years Review of RHCE Alleles Detected after Weak and/or Discrepant C Results in Southern France.

Immunohematology laboratories are regularly facing transfusion issues due to serological weaknesses. Altered (partial) RH antigens account for most of them. In some situations, RHCE variant alleles are involved. Herein we present our three-step molecular exploration, with allele frequencies, that has efficiently untangled RH2 phenotype weaknesses and discrepancies in our 2017-2021 cohort. In the last 5 years, the PACA Corse EFS molecular platform received 265 samples from healthy blood donors or patients with C and C/e typing difficulties. The first-intention technique (DNA array and real time PCR for RHCE*CeRN research) detected RHCE variant alleles in 143 cases (54%). The RHCE alleles classically found in African populations were the most frequent, with RHCE*CeRN allele in 40 cases (15%) and (C)ces haplotype type 1 and 2 in 26 cases (10%). A "CE" effect haplotype was suspected in 56 cases, due to the uncommon DCE haplotype that may explain the low C expression. When there were no RHCE*Ce or RHCE*CE alleles, we then searched for RHD polymorphisms by DNA array. We detected the RHD*DAU5 and RHD*DIVa in 18 and 7 cases respectively, suggesting that C ambiguity is related to the presence of these alleles which has never been described with DAU5. If no variant RHCE and RHD alleles were detected, we finally sequenced the 10 exons of both RHCE and RHD genes according to the clinical context and found seven new RHCE alleles. Thus, this molecular strategy would improve the knowledge of RHCE variants' expression and, thus, optimize the transfusion management.

Screening platelet function in blood donors.

BACKGROUND: Transfusion of defective platelets could contribute to the inefficiency of platelet transfusion in preventing or stopping bleeding. STUDY DESIGN AND METHODS: This single-center prospective study aimed to determine the prevalence of functional platelet abnormalities in a population of blood donors with a clinical history of bleeding diathesis or with history of hematoma (>4 cm) during blood donation. Donors with positive bleeding screening questionnaire were referred to the reference center for rare platelet diseases at La Timone University Hospital (Marseille) to confirm the bleeding tendency using a more extensive bleeding questionnaire (MCMDMscore) and to assess hemostasis, including a comprehensive platelet analysis. RESULTS: One hundred and ninety-five donors identified based on a history of hematoma and 2434 blood donors were included in the study. Eighty-eight donors (3.6%) had a bleeding score indicating a potential bleeding disorder. Five donors with a history of hematoma (2.5%) and 15 (17%) donors with a confirmed bleeding score underwent hemostatic analysis, including two men and 18 women with average age of 33.9 years. Minor hemostatic abnormalities were observed in three donors. Two donors exhibited accelerated fibrinolysis with reduced euglobulin lysis time and increased D-dimer levels in serum. Two donors had a platelet granule defect, without identification of genetic abnormality. CONCLUSION: The bleeding questionnaire proved to be a valuable tool to screen blood donors for potential platelet defects. Platelet dysfunction was rare in the blood donor population assessed. Additional studies are necessary to understand the clinical impact that the transfusion of platelets with qualitative defects has on recipients.