These carbohydrate moieties are recognized as foreign by the immune systems of other individuals, which produce antibodies to them. 2 Thus by definition, blood group antigens are secondary gene products the primary gene products are the various glycosyltransferase enzymes that attach the sugar molecules to the oligosaccharide chain. 2 In the mid-1940s, the antiglobulin test was developed, which allowed the detection of non-agglutinating antibodies, 1 and biochemical genetic investigations were undertaken, which established that the specificity of antigens was determined by their oligosaccharide structures. 1 His classification of the ABO blood groups and subsequent research by others confirmed that antibodies and antigens were inherited characteristics. Landsteiner’s discovery of blood groups in the early 1900s was based on the observation that some individuals' red cells agglutinated when mixed with plasma from other individuals.
Serological research has focused on identifying and understanding the structure, function, and interactions of serum antibodies and blood groups. Further research to identify differences in the biochemical composition of blood group antigens, and the relationship to risks for disease, can be important for the identification of targets for the development of nutritional intervention strategies, or the identification of druggable targets.
Recent advances in technology, biochemistry, and genetics have clarified the functional classifications of human blood group antigens, the structure of the A, B, H, and Lewis determinants and the enzymes that produce them, and the association of blood group antigens with disease risks. Blood group antigens are found on red blood cells, platelets, leukocytes, plasma proteins, certain tissues, and various cell surface enzymes, and also exist in soluble form in body secretions such as breast milk, seminal fluid, saliva, sweat, gastric secretions, urine, and amniotic fluid. The blood type is defined by oligosaccharide structures, which are specific to the antigens, thus, blood group antigens are secondary gene products, while the primary gene products are various glycosyltransferase enzymes that attach the sugar molecules to the oligosaccharide chain. In the 1950s, the chemical identification of the carbohydrate structure of surface antigens led to the understanding of biosynthetic pathways.
Associations between blood type and disease have been studied since the early 1900s when researchers determined that antibodies and antigens are inherited.