The antibodies are large complex protein molecules. One group, the antitoxins, act as antidotes, neutralizing the poisons that the microbes release into the body. The other group, the agglutinins, clump the microbes together so that they fall easy prey to the white blood cells, or leukocytes. These leukocytes develop in the bone marrow and are always present in the blood.
Some of them surround the infected area and quarantine it by making a wall with their own bodies. Within the barricade, the rest of them attack the microbes and eat them up. Like tiny amoebas, they crawl about and stretch out foot-like projections called pseudopods which they use to engulf bacteria and digest them. This explains their other name phagocyte or eating cell. Each phagocyte can eat about a dozen bacteria this way, a process called phagocytosis.