antibody

antibody A specialized immune protein (an immunoglobulin) produced because of the introduction of an antigen into the body. An antibody possesses the remarkable ability to combine with the antigen that triggered its production. The production of antibodies is a major function of the immune system and is carried out by a type of white blood cell called a B cell, or a B lymphocyte. Antibodies can be triggered by, and directed toward, foreign proteins, microorganisms, or toxins. Antibodies that are directed against one’s own tissues are referred to as autoantibodies. See also immune system.