Red cell antigen testing

The testing of red cell antigens in blood donors and blood recipients is the basic and most important part of the pretransfusion diagnostics. Depending on the national guidelines, the testing includes different mandatory typing ranging from ABO only up to ABO, RhD, RhCcEe, K and the RhD genotyping of serologically RhD‐negative donors. Testing of additional blood group antigens in blood donors and recipients is needed to provide compatible blood products for patients with clinically significant red cell antibodies. The red cell antigen testing is performed by a variety of serological methods mostly using haemagglutination test. For typing of ABO, RhD, RhCcEe, K and some further antigens, monoclonal IgM sera have become standard reagents. However, for extended antigen testing, polyclonal sera remained the most frequently used reagents. For some antigens, no certified commercial sera are available. The testing of the antigens has different significance in blood donors and recipients. Because of possible false‐negative reactions with weak or partial antigens, the typing of blood donors requires more sensitive techniques and reagents. In the last 10 years, molecular DNA typing of blood group alleles has become available for the routine. Providing genotypes, it gives essential information predicting the phenotype of red cell antigens when serological testing is not possible because of reagent limitations or in pretransfused patients.