White blood cells(WBC), also calledleukocytesorleucocytes, are thecellsof theimmune systemthat are involved in protecting the body against bothinfectious diseaseand foreign invaders. All leukocytes are produced and derived from amultipotentcell in thebone marrowknown as ahematopoietic stem cell. Leukocytes are found throughout the body, including thebloodandlymphatic system.[1]Five different and diverse types of leukocytes exist.[2]These types are distinguished by their physical and functional characteristics.Monocytesandneutrophilsarephagocytic.The number of leukocytes in thebloodis often an indicator ofdisease. The normal white cell count is usually between 4 and 11 109/L. In the US this is usually expressed as 4,00011,000 white blood cells per microliter of blood.[3]They make up approximately 1%