Chapter 4 - Red Blood Cell Antigens and Human Blood Groups

Abstract

This chapter describes red blood cell (RBC) antigens, which are most commonly encountered in the clinical practice of transfusion medicine. Blood group antigens are determined by either carbohydrate moieties linked to proteins or lipids, or by amino acid (protein) sequences. Specificity of the carbohydrate-defined RBC antigens is determined by terminal sugars; genes code for the production of enzymes that transfer these sugar molecules onto a protein or lipid. Specificity of the protein-defined RBC antigens is determined by amino acid sequences that are directly determined by genes. Many factors influence the clinical significance of alloantibodies formed against RBC antigens. The prevalence of different RBC antibodies depends on both the prevalence of the corresponding RBC antigen in the population and the relative immunogenicity. The clinical importance of an RBC antibody depends on both its prevalence in a population and whether it is likely to cause RBC destruction or hemolytic disease of the newborn (HDN). The chapter also reviews the type and degree of transfusion reactions and the degree of clinical HDN caused by antibodies to each blood group antigen system.