Background. - Prevention of hemolytic transfusion reactions depends upon our capacity to prevent allo-immunization and conflicts between antigens of transfused red blood cells and antibodies produced by the recipient. In this study, we show that to secure transfusion of sickle cell disease patients, it is necessary to take into account their immunohematologic characteristics in the organization of transfusion.Methods and results. - Immunohematological data of 206 chronically transfused patients have been collected its well as phenotypes of transfused units. In order to prevent allo-immunization against C and E antigens for patients typed D+C-E-c+e+ (56%), 26% of the transfused units were D-C-E-c+e+. We found that 47% of the patients had a history of allo-immunization, whereas only 15% produced an antibody the day of inclusion in the Study. The non-detectable antibodies were frequently known as dangerous for transfusion. Finally. this study shows the frequency of anti-D in D+ patients and anti-C in C+ patients, pointing out the question of partial antigens.Conclusion. - To insure optimal transfusion safety for sickle cell disease patients, three points have to be unproved: blood donation within the Afro-Caribbean community living in France, access to history of immuno-hematological data, detection of variant antigens, especially within the RH blood system. (C) 2009 Publie par Elsevier Masson SAS.

We read with interest the recently published paper (Ranasinghe et al, 2001) on the provision of platelet support for fetuses and neonates affected by severe fetomaternal alloimmune thrombocytopenia (FMAIT). In this situation, there is a high risk of potentially life-threatening bleeding while the number of thrombocytes remains below 20–30 × 109/l, and the most rapid and effective treatment is immediate transfusion of compatible platelets (Letsky & Greaves, 1996). The antibodies involved are anti-human platelet antigen (HPA)-1-a in 80–90% of cases and anti-HPA-5-b in 5–15% of cases, with other platelet antibodies rarely involved (Letsky & Greaves, 1996). Ranasinghe et al (2001) screened over 60 000 blood donors to obtain 45 HPA-1-a-negative donors suitable for plateletpheresis and available if fetal or neonatal platelet transfusion was required. We would like to report another approach tested by our blood centre, which has developed a protocol to maintain a permanent stock of HPA-1-a-negative platelet concentrates (PC). Group O plateletpheresis blood donors are routinely HPA phenotyped by our Platelet Immunology Laboratory to provide a panel for platelet antibody screening. We therefore established a cohort of platelet blood donors phenotyped for the HPA-1, 3 and 5 systems and for the CD36 molecule. For these donors, HPA phenotyping is performed twice and we screen for antibody to HPA antigen in HPA-1-a-negative donors using the Platelet Suspension Indirect Immunofluorescence Test (PSIIFT) and the Monoclonal Antibody-specific Immobilization of Platelet Antigen (MAIPA) test. The 363 plateletpheresis blood donors phenotyped for HPA systems and attending our blood centre include 10 currently active HPA-1-a/HPA-5-b-negative donors, without platelet antibody. These donors can give platelets up to three times a year for men and twice a year for women. The adult HPA-1-a-/HPA-5-b-negative PC obtained (one adult PC contains a mean of 4–7 × 1011 platelets) are divided into two or three paediatric PC, which are then frozen in dimethylsulphoxide (DMSO) for cryoprotection (final concentration 5%) within 24 h, preferably at −196°C in liquid nitrogen, but occasionally at −80°C in a freezer (Barnard et al, 1999). Under French legislation, PC treated in this way may be stored for up to 3 years. At each platelet donation, blood donors are systematically subjected to the following mandatory tests: blood groups ABO Rhesus and Kell, tests for antibodies against erythrocyte antigens other than ABO, high titres of anti-A and/or anti-B, infectious markers such as alanine aminotransferase (ALT), hepatitis B virus (HBV) surface antigen (HBsAg), HBV antibody (HBcAb), antibodies against hepatitis C virus (HCV), human immunodeficiency virus (HIV) 1/2, Human T-lymphotropic virus (HTLV) I/II and the agent of syphilis, HCV and HIV antigens using polymerase chain reaction (PCR) screening. Tests for cytomegalovirus (CMV) antibody are also performed if previous test results were negative. PC are accredited only if the clinical assessment has been successfully validated by the blood donor and if mandatory tests present no abnormalities. In cases of severe FMAIT requiring transfusion, accredited frozen PC are thawed and washed. This operation takes no longer than 90 min. The paediatric unit is then infused into the thrombocytopenic neonate in a volume of 20 ml/kg, generally leading to a significant increase in platelet counts (Table I). In our experience, this approach is the most rapid and safest way to provide HPA-compatible PC, particularly because blood donors, even if available when called, may be disqualified from blood donation on clinical grounds or as a result of abnormal results in mandatory biological tests. Furthermore, for each blood donation, there is a waiting period of 24–48 h before the results of the tests required for certification of the PC become available. If the approach described here is used, accredited HPA-phenotyped PC are always available within a reasonable time period.

To characterize the antigenic targets of anti-platelet antibodies (APA) found in systemic lupus erythematosus (SLE)-associated thrombocytopenia, 48 patients with immune thrombocytopenia and SLE were compared with 20 patients with SLE who had never been thrombocytopenic. Both cases and controls were tested for circulating APA by an indirect platelet suspension immunofluorescence assay (PSIIFT) and by indirect monoclonal antibody specific immobilization of platelet antigens (MAIPA). A direct platelet suspension immunofluorescence assay (PSIFT) was also used for antibodies bound to platelets in vivo in thrombocytopenic patients; 13 of them with high titres of platelets-bound APA were investigated by direct and indirect MAIPA and platelet eluate analysis. Circulating APA were detected by PSIIFT in 88% of cases and 55% of controls (P = 0.0066) and platelet-bound antibodies were detected by PSIFT in 90% of cases. Indirect MAIPA detected specific APA (mainly directed against GpIIbIIIa) in 36% of cases and only 5% of the controls (P = 0.0076). Nine out of the 13 fully investigated thrombocytopenic patients (69%) had a positive direct MAIPA and/or APA detected in platelet eluates. In conclusion, the production of specific anti-platelet autoantibodies, mainly directed against GpIIb/IIIa, and their binding to platelet membrane plays an important role in the pathogenesis of SLE-associated thrombocytopenia.

It is thought that an increase in the adhesion of circulating reticulocytes to the vascular endothelium may initiate the vascular occlusion underlying the painful crises and organ failures typical of sickle cell disease (SCD). At least 2 receptors, usually present on reticulocytes, seem to be involved in this adhesion process: glycoprotein CD36 (glycoprotein IV) and integrin alpha(4)beta(1) (very late activation antigen--4). Recently, a high frequency of the platelet CD36--deficient phenotype was reported in black Africans. The frequency of this deficiency was similar in subjects with and without SCD. The role of CD36 in vaso-occlusion was then investigated by comparing the clinical course in 2 groups of black Africans homozygous for hemoglobin S, with and without CD36 deficiency, but similar in age, sex, geographical origin, number of alpha-globin genes, and beta-globin gene haplotype. Flow cytometry showed that CD36 was absent from the circulating red blood cells and reticulocytes of platelet CD36--deficient individuals but present on those from patients with normal platelet CD36 expression, and that alpha(4)beta(1) integrin levels were similar on the reticulocytes of the 2 groups. Neither clinical severity, as evaluated by the frequency and characteristics of vaso-occlusive events, nor biological data differed significantly in the 2 groups of patients. Finally, although CD36 has been suggested to play a critical role in the pathogenesis of vaso-occlusion, this study, despite including only a small number of patients, supports the idea that the modulation of expression of a single type of adhesion molecule is insufficient to counteract the pathological process leading to vaso-occlusion in SCD patients. (Blood. 2001;98:966-971)

BACKGROUND: CD36 is expressed on several cell lineages. About 5 to 10 percent of Asians lack platelet membrane CD36 (pCD36), but the frequency of pCD36 deficiency in other ethnic groups is not known. Persons who are pCD36‐negative are apparently healthy but can develop CD36 isoimmunization.STUDY DESIGN AND METHODS: The pCD36 phenotype was studied in 1885 subjects belonging either to a group of 1127 healthy French blood donors (almost all of whom were white Europeans) or to a group of 758 patients of known ethnic origin.RESULTS: No pCD36‐negative persons were found among the blood donors. Only 1 of the 301 white European patients was pCD36‐negative. In contrast, 16 of the 206 sub‐Saharan Africans was pCD36‐negative, a proportion higher than that among that black Caribbeans (1/148, p<0.01). The frequency of pCD36‐negative patients was similar in blacks with and without sickle cell disease. Monocyte CD36 (mCD36) expression was studied in 15 of 22 pCD36‐negative individuals: it was <10 percent in 7 subjects (type I deficiency) and between 12 and 100 percent in 8 others (type II deficiency). Thirteen pCD36‐negative individuals had risk factors for immunization, and 4 had anti‐CD36. Some had a history resembling posttransfusion purpura (n = 2), platelet transfusion refractoriness (n = 1), and recurrent miscarriage (n = 1). No correlation was found between immunization and the amount of mCD36. Anti‐CD36 from an immunized type II‐deficient woman reacted with monocytes from normal controls but not with monocytes from type I‐ or type II‐deficient individuals, and thus it is postulated that mCD36 could be structurally different in normal and type II CD36‐deficient individuals.CONCLUSION: CD36 deficiency is frequent in sub‐Saharan Africans; development of anti‐CD36 can lead to serious complications in multiply transfused patients, such as those with sicke cell disease.

The clinical and biological heterogeneity of sickle cell hemoglobin (Hb) C disease (SC disease) is similar to sickle cell anemia, but has a much milder course. The effect of genetic factors such as alpha thalassemia or beta-globin gene haplotype has been analyzed in a limited number of cases. In this work, we report about 114 adult SC patients, aged 15 to 65 years (M/F = 0.93). The frequency of deletional alpha thalassemia (alpha(-3.7)) was found to be about 35%. The coinheritance of an alpha-thalassemia trait with SC disease had no effect on the hemoglobin level but hemolysis was significantly reduced. In these patients, as described for homozygous Hb S individuals, the Hb F level was higher in females than in males and in individuals carrying the beta(s)-Senegal haplotype. This haplotype involves the presence of an Xmnl site 5' to Ggamma, which is considered responsible for an increased Ggamma/Agamma ratio. Our survey showed that some genetic factors may modulate hematological parameters in SC disease.

Priapism is a frequent and serious cause of morbidity in males with sickle cell disease. Acute priapism (AP) is preceeded in two-thirds of the cases by repeated minor events called stuttering priapism (SP). Since 1994, we have used a specific approach to prevent the commonly devasting effects of AP, using the alpha adrenergic agent etilefrine. Treatment of AP has been simplified (drainage without aspiration followed by one or two intracavernous injections (ICI) of 10 mg of etilefrine, until detumescence). For SP lasting more than one hour or causing pain, we use oral etilefrine and/or self ICI. This strategy was effective in five patients seen having AP, 21 patients with SP; it is simple, cheap, and avoids surgical procedure and transfusion. Morever, erectile dysfunction, present in three patients, has been treated safely by ICI of protaglandins.

Priapism is a frequent and serious cause of morbidity in males with sickle cell disease. Acute priapism (AP) is preceeded in two-thirds of the cases by repeated minor events called stuttering priapism (SP). Since 1994, we have used a specific approach to prevent the commonly devastating effects of AP, using the alpha adrenergic agent etilefrine. Treatment of AP has been simplified (drainage without aspiration followed by one or two intracavernous injections (ICI) of 10 mg of etilefrine, until detumescence). For SP lasting more than one hour or causing pain, we use oral etilefrine and/or self ICI. This strategy was effective in five patients seen having AP, 21 patients with SP; it is simple, cheap, and avoids surgical procedure and transfusion. Moreover, erectile dysfunction, present in three patients, has been treated safely by ICI of protaglandins.

Priapism is a frequent and serious cause of morbidity in males with sickle cell disease. Acute priapism (AP) is preceeded in two-thirds of the cases by repeated minor events called stuttering priapism (SP). Since 1994, we have used a specific approach to prevent the commonly devastating effects of AP, using the alpha adrenergic agent etilefrine. Treatment of AP has been simplified (drainage without aspiration followed by one or two intracavernous injections (ICI) of 10 mg of etilefrine, until detumescence). For SP lasting more than one hour or causing pain, we use oral etilefrine and/or self ICI. This strategy was effective in five patients seen having AP, 21 patients with SP; it is simple, cheap, and avoids surgical procedure and transfusion. Moreover, erectile dysfunction, present in three patients, has been treated safely by ICI of protaglandins.

Objectives. Priapism is a common and currently unsatisfactorily managed complication of sickle cell disease (SCD). In June 1994, 6 SCD patients received a new therapeutic regimen to prevent the occurrence and recurrence of priapism.Methods. The patients (5 with SS and 1 with SC) were adults and had frequent episodes of stuttering priapism (SP), and two of them had had acute episodes (AP) lasting more than 3 hours. The treatment consists of preventive oral administration of the alpha-adrenergic agent etilefrine, and self-administered intracavernous injection (SICI) of the same agent to reverse episodes lasting more than 1 hour.Results. Since the beginning of treatment, all patients were protected against AP, 4 patients had no recurrence with the oral treatment alone, 2 had to use SICI, occasionally and I constantly. There was no modification of sexual activity and no complications. Blood pressure was unaffected.Conclusions. This treatment is simple, cheap, and self-administered. It should be proposed to all patients with SCD in all geographic areas as part of an educational program for active prevention of this severe complication.