For the album by the band The White Stripes, see White Blood Cells (album) . 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.or the album by the band The White Stripes, see White Blood Cells (album) . 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.