Isoantigen

Isoantigen is a type of antigen that is found in some but not all members of the same species. Isoantigens can stimulate an immune response in individuals who do not possess them, leading to the production of antibodies. They are of particular importance in transplantation and blood transfusion medicine, as they can cause immune rejection of transplanted organs or tissues, and transfusion reactions in blood recipients.

Types of Isoantigens

There are several types of isoantigens, including blood group antigens, histocompatibility antigens, and minor histocompatibility antigens.

Blood Group Antigens

Blood group antigens are isoantigens that determine an individual's blood type. They are found on the surface of red blood cells and can cause immune reactions if blood from a donor with a different blood type is transfused into a recipient. The most well-known blood group antigens are the ABO and Rh antigens.

Histocompatibility Antigens

Histocompatibility antigens are isoantigens that play a crucial role in the immune system's ability to distinguish self from non-self. They are found on the surface of all nucleated cells and are the primary cause of organ transplant rejection. The most well-known histocompatibility antigens are the HLA antigens in humans.

Minor Histocompatibility Antigens

Minor histocompatibility antigens are isoantigens that can cause graft-versus-host disease (GVHD) in bone marrow transplant recipients. They are called "minor" because they cause less severe reactions than the major histocompatibility antigens.

Clinical Significance

Isoantigens have significant clinical implications, particularly in the fields of transfusion medicine and transplantation medicine. Understanding and managing the immune responses to isoantigens is crucial for the success of blood transfusions and organ transplants.

See Also

• Antigen
• Immune response
• Blood transfusion
• Organ transplantation

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