LEUKOCYTE

n.

or white blood cell or white corpuscle

Any of several types of blood cells that help defend the body from infection .

The different mature forms

granulocytes, including neutrophils (heterophils), basophils, and eosinophils; monocytes, including macrophages; and lymphocytes

have different functions, including ingesting bacteria , protozoans , or infected or dead body cells; producing antibodies ; and regulating the action of other leukocytes. They act mostly in the tissues and are in the bloodstream only for transport. Blood normally contains 5,000–10,000 leukocytes per cu mm.