White blood cell (WBCs) or leukocytes are produced by the body to fight infections. However, there are many types of WBCs, such as neutrophils, eosinophils, basophils, lymphocytes, and monocytes. Out of all these, lymphocytes and neutrophils are the two most common types of WBCs.

Lymphocytes are generated by the lymphoid tissue in the spleen, lymph nodes, and thymus gland. The basic function of lymphocytes Includes identifying alien substances, such as bacteria or viruses in the body and produce antibodies and that target them. However, it often takes several days for lymphocytes to identify and strike an alien substance.

Neutrophils, on the other hand, are made in the bone marrow and circulate in the bloodstream. Neutrophils form a strong defensive system against bacterial infections. They leave the blood vessels and enter the infected tissues to fight with the bacteria. Generally, the body produces greater number of neutrophils, if countered by an acute bacterial infection. Therefore, if the WBC count is low in the body, it indicates the shortage of neutrophils.

A white blood cell count is performed by counting the number of WBCs in a given sample of blood. The normal WBC values are in the range of 4,000 to 11,000 cells per microliter. The person with a low WBC count suffers from a disease called leukopenia. However, a high WBC is called as leukocytosis.

A normal Absolute Neutrophil Count (ANC) is between 1,500 to 8,000 cells per microliter. If the ANC is below 500 over a period of time, the risk of serious bacterial infection is considerably high.