Tissue antigens: autoantigens, alloantigens, xenoantigens and neoantigens

The subject of Clinical Immunology is developing hand in hand with a wide and rapidly moving area of laboratory technology. The result is a better understanding of autoimmune disease, tissue transplantation rejection, foetal-maternal incompatibility, allergic disease, immunodeficiency disorders, adverse reactions to drugs, aberrant responses to bacterial and viral infections, and growth and spread of malignant cells. Basic to this understanding is the need to appreciate the character and composition of natural substances which act as immunogens and elicit antibodies. These substances have, according to their origin, been classified as autoantigens, alloantigens, xenoantigens and neoantigens. This review summarizes our knowledge relating to such antigens, emphasizing those aspects relevant to human disease and pointing to the major gaps that future research must bridge.