Production of antibodies against the tissues of one's own body, causing autoimmune disease or hypersensitivity reactions.

One of the five classes of immunoglobulins; widespread in the body, it is the main antibody defence against most bacterial invasions and other antigens.

Any of the five classes of structurally distinct antibodies produced in lymph tissue in response to a foreign substance. The five kinds are immunoglobulin A, D, E, G and M.

One of the five classes of immunoglobulins. One of the most common immunoglobulins, it is present in body secretions and is the chief antibody in the mucous membranes of the gastrointestinal and respiratory tract and in saliva and tears.

The body's means of protection against microorganisms and other foreign substances; it is composed of two major parts: the humoral response (B lymphocytes and production of antibodies) and the cell-mediated response (T lymphocytes that attack foreign substances directly).