Overview
Blood groups are inherited antigens on the red cell surface, and antibodies against the antigens a person lacks decide whether a transfusion is safe. This topic covers the ABO and Rhesus systems, their clinical significance, the methods of blood group analysis and the principles of blood transfusion.
Introduction to Blood Group Alloantigens
- Blood transfusion is a type of transplantation, where the donor’s red blood cells are introduced into the recipient’s bloodstream.
- Red blood cells (erythrocytes) do not express MHC (major histocompatibility complex) molecules, so they do not trigger a strong T-cell mediated immune response.
- However, red blood cells carry polymorphic surface carbohydrates and proteins that differ among individuals and can stimulate a strong antibody (humoral) immune response.
- These polymorphic molecules are called blood group antigens, and individuals with different forms of these antigens belong to different blood groups.
- A blood group system refers to a set of antigens controlled by alleles of a single gene. There are several systems, but ABO and Rhesus are the most clinically significant.