Any of various bodies or substances in the blood which act in antagonism to harmful foreign bodies, as toxins or the bacteria producing the toxins. Normal blood serum apparently contains various antibodies, and the introduction of toxins or of foreign cells also stimulates production of their specific antibodies by the immune system.
more narrowly, any of the immunoglobulins present in the blood serum or other body fluids of an animal, which reacts with a specific antigenic substance, whether the antibody was produced as a consequence of the stimulus provided by the antigen, or was pre-existing prior to exposure of the organism to the antigen.
a protein in the blood that is produced by certain white blood cells; develops primarily in response to foreign antigens; important for immunity against certain germs.
A type of protein that is part of the immune system. Antibodies recognize and attach themselves to infectious organisms and foreign materials so they can be removed from the body.