WBC

White Blood Cells

White blood cells, or leukocytes (also spelled "leucocytes"), are the cells of the immune system that are involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, and several types (including monocytes and neutrophils) are phagocytic. All leukocytes are produced and derived from a multipotent cell in the bone marrow known as a hematopoietic stem cell. They live for about three to four days in the average human body. Leukocytes are found throughout the body, including the blood and lymphatic system.

Reference

Wiki White Blood cell

Term first found in HGS Manual: Page 49