White corpuscle of blood.
Blood cells that engulf and digest bacteria and fungi; an important part of the body's defense system; SYN. leucocyte, white blood cell, white cell, white blood corpuscle, white corpuscle.
A white blood cell. Leukocytes are part of the body's defenses and give immunity against disease. There are several different types. Some (phagocytes and macrophages) engulf invading microorganisms, others kill infected cells, while lymphocytes produce more specific immune responses. Human blood contains about 11,000 leukocytes to the cubic millimeter—about 1 to every 500 red cells.
Leukocyte numbers may be reduced (leukopenia) by starvation, pernicious anemia, and certain infections, such as typhoid and malaria. An increase in the numbers (leukocytosis) is a reaction to normal events such as digestion, exertion, and pregnancy, and to abnormal ones such as loss of blood, cancer, and most infections.