Portal:Medicine/Selected article/1, 2007

A total of 29 human blood group systems are recognized by the International Society of Blood Transfusion (ISBT). The most important of these are the ABO blood group system and the Rhesus blood group system.

Each blood group is represented by a substance on the surface of red blood cells (RBCs). These substances are important because they contain specific sequences of amino acid and carbohydrate that are antigenic. As well as being on the surface of RBCs, some of these antigens are also present on the cells of other tissues. (More...)