Human Red Blood Cell (RBC) Blood Groups System

Understanding of the blood group system of human gives benefits in transplantation and transfusion medicine. Karl Landsteiner received Noble Prize in 1930, and Jan Jansky classified human blood groups to four different blood group types. The human blood group genes are present in allelic or located on the identical chromosomal region. Blood type indicates a specific reaction pattern to antiserum in a given system. Blood group is antigenic determinant antigens expressed on cellular surfaces of RBC. Human blood group system thus contains several distinct antigenic determinants and expanded to transfusion complications [1]. Currently, 33 blood group systems classified show over 300 antigens [2], and each coding gene is autosomal. Only XG and XK genes are located on sexual chromosome X. Both X and Y chromosomes carry MIC2 gene. Amino acid sequence variation causes the antigen polymorphisms in Rh, Kell, and glycolipids as well as glycoproteins in ABO type (Table 6.1). Currently, four main types of A, B, AB, and O blood groups commonly present in human are expressed due to their inherited determination. Each group is either Rhesus (Rh) D positive (+) or RhD negative (−), possibly giving eight blood groups. The Rh antigens are only present on RBCs. Each blood group antigen has been identified by human natural antibodies and blood antigen molecules on the RBC surfaces. Currently, ISBT termed from the International Society of Blood Transfusion has a definition of 33 independent systems of human blood group (Table 6.1). The known specific antigens, but not RhD, are expressed on normal blood cells and tissues. Apart from ABO and Rhesus systems, the RBC membrane antigens represent the blood groups. The ABO antigens widely present in the body refer to histo-blood group antigens. Some systems have only one determinant, and other systems have on more multiple determinants such as MNS and Rh. The MNS blood group consists of three genes, while the Chido/Rodgers blood group and Rh group are comprised of two genes. Some systems consist of a single gene. In addition, more 30 RBC antigens present in very high or very low prevalent levels are not characterized yet. Blood groups are inherited, and some groups are environmentally, developmentally, or by disease changed.