<span>If the abnormal cells are primarily granulocytes (which destroy bacteria) or monocytes (which produce large cells called macrophages, which digest foreign substances and diseased cells), the leukemia is classified as myelogenous. If the abnormal cells are mainly lymphocytes (which orchestrate the immune system’s response to infection or disease), the leukemia is classified as lymphocytic.</span>Leukemia arises from malfunctions in stem cells within the bone marrow that cause abnormal white blood cells to flood into the bloodstream. Leukemias are classified as either myelogenous (also called myeloid) or lymphocytic depending on which types of white blood cells are affected.
