[Blood groups and structure-activity relations]

Influence des antigènes de groupes sanguins en transplantation

Blood group antigens seem to be implied in the mechanisms of tissue and cell rejection. All erythrocyte blood groups are not only demonstrated on red cells. Some of them can be observed on several tissues of the body, particularly antigens of ABO, Hh, Lewis and I(i) systems... These ubiquitory antigens, called "histo-antigens" are developed very early at the various embryofetal stages depending on the tissues. The ABO system plays a fundamental role in graft and transplant. If the ABO compatibility is fundamental for the prognosis of a kidney, liver and heart transplantation, it has only a minor effect on the marrow, bone or cornea transplantation. The physiopathologic mechanisms are known, for the main points, and in connection with ABH antigens presence. Recent works show that systems RH, FY and JK could play a role in the process of graft rejection.

Insights into the structure and function of membrane polypeptides carrying blood group antigens

In recent years, advances in biochemistry and molecular genetics have contributed to establishing the structure of the genes and proteins from most of the 23 blood group systems presently known. Current investigations are focusing on genetic polymorphism analysis, tissue-specific expression, biological properties and structure-function relationships. On the basis of this information, the blood group antigens were tentatively classified into five functional categories: (i) transporters and channels, (ii) receptors for exogenous ligands, viruses, bacteria and parasites, (iii) adhesion molecules, (iv) enzymes and, (v) structural proteins. This review will focus on selected blood groups systems (RH, JK, FY, LU, LW, KEL and XK) which are representative of these classes of molecules, in order to illustrate how these studies may bring new information on common and variant phenotypes and for understanding both the mechanisms of tissue specific expression and the potential function of these antigens, particularly those expressed in nonerythroid lineage.