Biology of chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is a clonal proliferation of mature-appearing, but maturationally immature B cells; T cells are rarely involved. Most data suggest that CLL cells are frozen at an early step in maturation; this can be overcome by several techniques such as in vitro incubation with tumor promotors. Although B-CLL involves B cells, and abnormal T cell function is common, its etiology is uncertain. Oncogene abnormalities and retroviral infection have been reported in rare cases of CLL; their role in more typical cases is unknown.