Leukocytes

Picture, Function, and Percent

Granular Leukocytes

Granular Leukocytes

Neutrophil, Eosinophil, Basophil

Agranular Leukocytes

Lymphocyte, Monocyte

Neutrophil

Neutrophil

60-70%

Neutrophil

Phagocytosis. Destruction of bacteria with lysozyme, defensins, and strong oxidants, such as superoxide anion, hydrogen peroxide, and hypochlorite anion

Eosinophils

Eosinophils

2-4%

Eosinophils

Combat effects of histamine in allergic reactions, phagocytize antigen–antibody complexes, and destroy certain parasitic worms

Basophils

Basophils

0.5-1%

Basophils

Liberate heparin, histamine, and serotonin in allergic reactions that intensify overall inflammatory response.

Lymphocytes

Lymphocytes

20-25%

Lymphocytes

Mediate immune responses, including antigen–antibody reactions. B cells develop into plasmocytes, which secrete antibodies. T cells attack invading viruses, cancer cells, and transplanted tissue cells. Natural killer cells attack wide variety of infectious microbes and certain spontaneously arising tumor cells.

Monocytes

Monocytes

3-8%

Monocytes

Form platelet plug in hemostasis; release chemicals that promote vascular spasm and blood clotting.