The Full form of WBC is White Blood Cell. WBCs are one of the cells the body makes to help fight infections. There are several types of White Blood Cells (leukocytes). The two most common types are the lymphocytes and neutrophils (also called polymorphonuclear leukocytes, “polys” or PMNs). Lymphocytes are made in lymphoid tissue in the lymph nodes, spleen and thymus gland. There are different kinds of lymphocytes. Lymphocytes identify foreign substances from germs (viruses or bacteria) in the body and produce cells and antibodies that specifically target them. It takes from several days to weeks for lymphocytes to recognize and attack a new foreign substance. Neutrophils are also major players in the body’s defense against bacterial infections. Neutrophils circulate in the bloodstream and are made in the bone marrow. Neutrophils move out of the blood vessels into the infected tissue to attack the bacteria. The pus in a boil (an abscess) is made up largely of neutrophils. The White Blood Cell count is done by counting the number of White Blood Cells in a sample of blood. A normal WBC is in the range of 4,000 to 11,000 cells per microliter. A low WBC is called leukopenia. A high WBC is termed as leukocytosis.