Human Blood Group Antigens and Antibodies
Pretransfusion testing includes ABO and Rhesus (Rh) type, and antibody screening to determine whether a patient has an unexpected red blood cell (RBC) antibody against a blood group antigen. If the antibody screen is positive, an identification panel is performed to identify the specificity of the antibody. Blood group antigens are polymorphic, inherited, carbohydrate, or protein structures located on the surface of the RBC membrane. There are more than 300 blood group antigens, most of which are included in 38 different blood group systems. The majority of genes encoding blood group antigens have been identified and cloned, and the molecular basis of most blood group antigens has been determined. Although the simple hemagglutination test remains the principal assay for RBC antigen typing for ABO and Rh, antibody screen, and compatibility testing; DNA -based typing (genotyping), especially for the minor blood group antigens, has become commonplace in some clinical situations.
