A young white blood cell white blood cell: Cells in the body that fight disease and infection by attacking and killing germs. There are several types of white blood cells including neutrophils, eosinophils, basophils, lymphocytes and monocytes. Each type of cell fights a different kind of germ. Also called WBC, leukocyte. . The number of blast cells in the bone marrow bone marrow: The soft, spongy tissue inside most bones. Blood cells are formed in the bone marrow. helps define how severe MDS is in a person. When 20 out of 100 cells in the bone marrow are blasts blasts: See Blast Cells. , this is considered acute myeloid leukemia acute myeloid leukemia: (uh-KYOOT my-uh-LOYD loo-KEE-mee-uh) A cancer of the blood cells. It happens when very young white blood cells (blasts) in the bone marrow fail to mature. The blast cells stay in the bone marrow and become to numerous. This slows production of red blood cells and platelets. Some cases of MDS become… .
