Immunology Disorders

Immunology is the study of the body's natural defense mechanisms against disease and the responses of the body when challenged by antigens. Antigens include toxins or poisonous substances, bacteria and foreign blood cells, and the presence of antigens in the body triggers an immune response, usually the production of antibodies.

Inflammation and inflammatory diseases can be classified in a number of different ways, for example as allergies or autoimmune disease, but in all cases the common factor is that inflammation results from the inappropriate activation of the cells of the immune system. (For more information on allergies and respiratory disorders, see "Other" conditions.)

Autoimmune diseases comprise a growing group of medical conditions in which the body's own immune system fails to recognize the body as itself, mounts an abnormal immune attack and typically destroys afflicted tissue with severe results, for example, the lining of the gastrointestinal tract in
Crohn's disease.