Optimized Antigen-Matched in Sickle Cell Disease Patients: Chances and Challenges in Molecular Times - the Brazilian Way.

The development of red blood cell (RBC) alloantibodies and autoantibodies complicates transfusion therapy in sickle cell disease (SCD) patients. In an effort to reduce the risk of alloimmunization, some strategies have been used to provide antigen-matched RBC transfusions to patients with SCD in Brazil, including molecular matching in 3 levels: RH and K matching; extended matching (RH, KEL, FY, JK, MNS, DI), and extended matching including RHD and RHCE variant alleles. Molecular matching has shown clinical benefits to the patients with SCD, contributing significantly to reduce the rates of alloimmunization. Improvements in the clinical outcomes of the patients have also been observed as shown by an increase in their hemoglobin levels and reduction in their percentage of hemoglobin S as well as better in vivo RBC survival and diminished frequency of transfusions. However, prevention of RBC alloimmunization still remains a challenge in Brazil due to the difficulty to fulfill all transfusion requests of the patients with antigen-matching units, inaccuracy of RBC phenotyping, RBC transfusions outside the institution where the patient is treated, advanced age of some patients, the RBC antigen discrepancy between donors and recipients, and the presence of RH variants.