Disorders caused by problems with the body’s mechanisms for protecting itself against viruses, bacteria, and other foreign substances. Immune system disorders result in conditions in which some portion of the immune response is weak or absent. In one form of immune system disorders, called autoimmune disorders, the immune system mistakenly identifies the body’s own normal cells or tissues as foreign and attacks these cells and tissues as though they were antigens. Multiple interacting factors may contribute to the development of autoimmune diseases, including genetic predisposition, immunologic abnormalities, and even microbial infections.
Disorders of the immune system encompass immunodeficiency disorders and allergies. In immunodeficiency disorders, the immune system is weakened or ineffective in providing adequate protection against pathogens. On the other hand, allergies involve the immune system’s inappropriate response to typically harmless antigens like pollen, resulting in allergic reactions.
In specific situations, such as after tissue transplants, doctors may employ immunosuppressant drugs. These medications are used to suppress the immune system’s activity, thereby preventing the body from rejecting the transplanted tissue as a foreign entity.