Humoral immune response: the antibodies

The humoral immunity is the major defense mechanism against microorganisms extracellular and their toxins, in which the components of the immune system to attack the antigens, are not cells directly but are macromolecules, such as antibodies or proteins of the system complement. The antibodies  diffuse into the blood, the lymph, interstitial fluids and secretions (saliva , mucus, milk), which carry out their action.