They encourage the growth of cells, trigger cell activity, direct cell traffic, destroy target cells, and arouse phagocytes. Like killer T cells, NK cells are armed with granules filled with potent chemicals. Both kind of killer cells slay on contact. The deadly assassin binds to its target, aims its weapons, and then delivers a lethal burst of chemicals. Specialized types of macrophages can be found in many organs, including the lungs, the kindneys, the brain, and the liver.
Macrophages play many roles.
As scavengers, they rid the body of worn-out cells and other debris. They display bits of foreign antigen in a way that draws the attention of matching lymphocytes. Granulocytes are white blood cells that contain granules filled with potent chemicals, which allow the granulocytes to destroy microorganisms. Some of these chemicals such as histamine also contribute to inflammation and allergy. Rather, it is found in the lungs, skin, tongue, and linings of the nose and intestinal tract, where it is responsible for the symptoms of allergy.