alloantigenelor

Alloantigens are molecules found on the surface of cells that vary between individuals of the same species. These variations are due to genetic differences. The term "allo" comes from the Greek word "allos," meaning "other." Alloantigens are typically proteins, but can also be carbohydrates or lipids.

The most well-known examples of alloantigens are the ABO and Rh blood group systems in humans. Differences in these alloantigens determine a person's blood type. These antigens are crucial in blood transfusions, as the immune system of a recipient can recognize alloantigens on donor red blood cells as foreign and mount an immune response, leading to transfusion reactions.

Beyond blood groups, alloantigens are also important in tissue transplantation. The major histocompatibility complex (MHC) in humans, also known as human leukocyte antigens (HLA), presents a vast array of alloantigens on the surface of most nucleated cells. The immune system of the transplant recipient closely scrutinizes these HLA alloantigens. A mismatch in HLA alloantigens between the donor and recipient significantly increases the risk of graft rejection, where the recipient's immune system attacks and destroys the transplanted organ or tissue. Immunosuppressive drugs are often used to dampen this immune response and prevent rejection.

The study of alloantigens is vital in fields such as immunology, transfusion medicine, and transplantation. Understanding these molecules helps in preventing adverse immune reactions and improving the success rates of medical interventions that involve introducing foreign cells or tissues into the body.