Too few or too many white blood cells indicates a disorder. Leukopenia, a decrease in the number of white blood cells to fewer than 4,000 per microliter, makes a person more susceptible to infections. Most white blood cell disorders involve neutrophils, lymphocytes, monocytes, and eosinophils. Disorders involving basophils are very rare. Neutropenia Neutropenia is an abnormally low number of neutrophils in the blood.
Neutrophils are the body's primary cellular defense system against bacteria and fungi.
They also help heal wounds and ingest foreign debris, such as embedded splinters. Neutrophils mature in the bone marrow in about 2 weeks. After entering the bloodstream, they circulate for about 6 hours, searching for infective organisms and other intruders. When they find one, they migrate into the tissues, attach themselves to the intruders, and produce toxic substances that kill and digest the intruders. This reaction may damage healthy tissue in the area of the infection.