Blood typing is crucial in blood transfusion to prevent adverse reactions. The main blood group systems are the ABO system and the Rh system. In the ABO system, blood types are classified as A, B, AB, or O based on the presence of specific antigens on the surface of RBCs. The Rh system is based on the presence or absence of the Rh antigen (commonly the D antigen). Histologically, the antigens on the surface of RBCs can be identified using specific immunohistochemical techniques, which help in accurately typing blood for transfusion.
