Prognostic significance of the proportion of Ki-67-positive cells in adult T-cell leukemia.

The authors examined peripheral blood samples from patients with adult T-cell leukemia (ATL) using the monoclonal antibody Ki-67 which detects a nuclear antigen present in actively proliferating cells. In patients with chronic ATL, the percentage of Ki-67-positive cells was significantly lower than in acute ATL patients (median values, 3.3% versus 18.9%, P less than 0.001). Furthermore, there was a significant inverse correlation between the percentage of Ki-67-positive cells and the length of survival (P less than 0.001). Serum lactic dehydrogenase (LDH) levels also showed a significant inverse correlation with survival, but this was less strong than that for Ki-67 (0.01 less than P less than 0.02). Thus, Ki-67 positivity appears to indicate the aggressiveness of ATL, and can possibly be used for the clinical classification of ATL patients as well as for the prediction of prognosis.