What is “chronic lymphocytic leukemia” (CLL)?
Chronic lymphocytic leukemia is a type of cancer in which the bone marrow makes too many lymphocytes. Chronic lymphocytic leukemia (also called CLL) is a blood and bone marrow disease that usually gets worse slowly. CLL is the second most common type of leukemia in adults. It often occurs during or after middle age; it rarely occurs in children. Normally, the body produces bone marrow stem cells (immature cells) that develop into mature blood cells. There are 3 types of mature blood cells: • Red blood cells that carry oxygen and other materials to all tissues of the body. • White blood cells that fight infection and disease. • Platelets that help prevent bleeding by causing blood clots to form. In CLL, too many stem cells develop into a type of white blood cell called lymphocytes. There are 3 types of lymphocytes: • B lymphocytes that make antibodies to help fight infection. • T lymphocytes that help B lymphocytes make antibodies to fight infection. • Natural killer cells that attack c
