It involves the white blood cells known as leukocytes. Two major forms of chronic leukemia are chronic lymphocytic leukemia or chronic myelogenous leukemia. White blood cells defend the body against infection.
Blood cells grow in the bone marrow.
They are supposed to be fully grown when they enter the bloodstream. Leukemia causes white blood cells to lose their ability to mature fully. Immature cells take over the marrow and prevent it from making enough of the red and white blood cells and platelets that your body needs. Initial symptoms are vague. Usually you just don't feel very well.