Cytokinetic studies in chronic lymphocytic leukemia. Relationship to other variables at diagnosis and survival.

In vitro 3H-thymidine labeling index (LI) of the marrow leukemic cells was determined at diagnosis in 70 patients with chronic lymphocytic leukemia (CLL). Very little labeling of leukemic lymphocytes was observed, median LI resulting as low as 0.05%. The initial LI was unrelated to age, sex, absolute number of circulating lymphocytes, degree of marrow lymphocytosis, clinical staging or survival. We conclude that the initial LI% of the marrow leukemic cells is neither a valid nor practical prognostic factor in patients with CLL.