Blood Transfusion Guidelines for Sickle Cell Disease

Introduction to C Antigen

The C antigen is a clinically significant blood group antigen in the Rh system that requires prophylactic matching for patients with sickle cell disease to prevent alloimmunization and associated transfusion reactions, particularly in patients with sickle cell disease who have partial C antigens, with a prevalence of anti-C production in approximately 30% of cases 1

C antigen mismatch is a major cause of alloimmunization in transfusion recipients, particularly in patients with sickle cell disease, with anti-C antibodies developing when C-negative individuals are exposed to C-positive blood through transfusion or pregnancy 1
Rh (C, E or C/c, E/e) and K antigen matching reduces alloimmunization incidence from 1.94 to 0.40 new alloantibodies per 100 units transfused, based on moderate certainty evidence showing significant reduction in alloimmunization rates 1
Extended matching significantly reduces alloimmunization rates, with Rh- and K-matched red cells having an alloimmunization incidence rate of 0.9 per 100 transfused units compared to 3.1 for ABO/RhD-matched red cells only 1

Patients with sickle cell disease are at high risk of developing anti-C antibodies, particularly those with partial C antigens, and should receive C-negative blood to prevent alloimmunization 1
Patients identified by genotype with hybrid RHDDIIIa-CE (4-7)-D or RHCECeRN alleles encode partial C antigens and should receive C-negative red cells to prevent allo-anti-C development 1

C antigen typing can be performed using serologic methods (hemagglutination or gel column techniques) or molecular genotyping, with molecular genotyping providing improved accuracy for C antigen determination, especially in recently transfused patients, patients with interfering antibodies, and patients with suspected variant antigens 1
Blood typing for the C antigen should be performed in clinical laboratory settings using standardized methods such as hemagglutination or gel column techniques 2
Molecular genotyping provides improved accuracy for C antigen typing compared to serologic methods, especially in recently transfused patients or those with interfering antibodies 1

Extended red cell antigen profiling should be performed at the earliest opportunity, optimally before the first transfusion, to reduce the risk of alloimmunization and improve patient outcomes 1
Having extended red cell antigen profiles available expedites compatibility workup and aids in selection of compatible donor units, particularly for patients with sickle cell disease who are at high risk of developing anti-C antibodies 1
Extended matching may include additional antigens (Jka/Jkb, Fya/Fyb, S/s) for further protection, particularly for patients with partial C antigen who are at high risk of developing anti-C antibodies 1
The American Society of Hematology (ASH) strongly recommends prophylactic red cell antigen matching for Rh (C, E or C/c, E/e) and K antigens over only ABO/RhD matching for patients with sickle cell disease (SCD), based on moderate certainty evidence 1
Extended antigen typing, including C antigen, is particularly important for patients with sickle cell disease, chronically transfused patients, patients who have already developed alloantibodies, and pregnant women with a history of hemolytic disease of the fetus and newborn 1
Extended phenotyping, including C antigen testing, is recommended for patients who may require multiple transfusions 2