what does white blood cells do
White blood cells (WBCs), also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders.All leukocytes are produced and derived from a multipotent cell in the bone marrow known as a hematopoietic stem cell.he number of leukocytes in the blood is often an indicator of disease, and thus the WBC count is an important subset of the complete blood count. The normal white cell count is usually between 4 and 11 Ã 10 9 /L. In the US this is usually expressed as 4,000â11,000 white blood cells per microliter of blood.