A special kind of blood protein secreted by B-lymphocytes, which are a type of white blood cell in the immune system. Antibodies are synthesized in response to the presence of a particular antigen (foreign or potentially dangerous substances such as bacteria and viruses) and they circulate in the bloodstream to attack the antigen and render it harmless. Antibodies bind to the antigen causing less damage to occur and helping white blood cells destroy the foreign object.
