RESUMO
BACKGROUND: RBC alloimmunization remains a significant problem for many patients with SCD. To reduce alloimmunization some strategies have been implemented to provide limited or extended antigen matched RBC transfusions to patients with SCD who need chronic transfusion support. The aim of this study was to evaluate the effects of prophylactic RBC transfusion with extended antigen matching on alloimmunization in patients with SCD. METHODS: This is a 20-year retrospective study of patients with SCD transfused with RBCS that were prospectively matched for D, C, c, E, e, K, Fya/Fyb, Jka/Jkb and S antigens. Our study included 95 patients, and none had antibodies documented before their first transfusion. Patients and donors were phenotyped and molecular typing was performed in all patients who had recent transfusions or a positive direct antiglobulin test to predict their antigen profile. Unexpected antibodies to the Rh system, meaning anti-Rh antibodies in patients whose serologic phenotype was Rh positive, were investigated by molecular genotyping for RH variant alleles. RESULTS: During this study-period, 12 (12.6%) were alloimmunized and 83 (87.4%) were not. Among the 12 patients who alloimmunized, 7 (58.3%) developed antibodies to Rh antigens and 5 (41.7%) produced antibodies to low prevalence antigens. All patients who developed Rh antibodies had RH variant alleles. Autoantibodies were found in 16 (16.8%) transfused patients. CONCLUSION: SCD patients benefit from receiving prophylactic RBC transfusions with extended antigen matching, as demonstrated by the reduction on the rates of alloimmunization and the lack of antibodies to K, FY, JK and S antigens, however, this strategy does not avoid alloimmunization to Rh and low-prevalence antigens.
Assuntos
Anemia Hemolítica Autoimune , Anemia Falciforme , Antígenos de Grupos Sanguíneos , Humanos , Estudos Retrospectivos , Eritrócitos , Transfusão de Eritrócitos , Transfusão de Sangue , IsoanticorposRESUMO
BACKGROUND: Red blood cell (RBC) alloimmunization is a complication of patients with sickle cell disease (SCD) and it has a greater impact on pregnancy, leading to a risk of hemolytic disease of the newborn and reducing blood availability for pregnant women. This study proposed to evaluate antigen matching transfusion protocols, aiming to reduce RBC alloimmunization in Brazilian female patients with SCD. METHODS: Samples from female patients with SCD (153) and self-declared Afro-Brazilian donors (307) were genotyped for RBC antigens and RH variants were investigated. The transfusion needs of patients during 1-year period and the number of compatible donors were assessed using three antigen-matching transfusion protocols: prophylactic CEK antigen-matched RBCs, prophylactic extended antigen-matched RBCs, and extended-matched red blood cells (RBCs) only for alloimmunized patients. In addition, RH molecular matching has been proposed for patients carrying variant RHCE. RESULTS: Provision of CEK antigen-matched donors would have been possible in 92.4% of transfusion events while provision of prophylactic extended antigen-matched RBCs would cover 88.7% of the transfusion events. Extended antigen matching for alloimmunized patients would be efficient in 99% of the cases. The presence of partial D in 10 patients increased the need of D-negative donors. Compatible donors could be enough for four of the five patients with altered RHCE genotypes in both alleles. CONCLUSION: In Brazilians, screening African descent donors allows the implementation of prophylactic CEK and extended antigen-matching transfusion protocols to female patients with SCD to reduce RBC alloimmunization; however, the supply of compatible blood can be impaired for patients with Rh variants.