Prognostic value of B‐cell mitogen‐induced and spontaneous thymidine uptake in vitro in chronic B‐lymphocytic leukaemia cells

Abstract

Blood lymphocytes from 50 patients with chronic B-lymphocytic leukemia (B-CLL) were cultured in vitro with and without the polyclonal B-cell activators (PBA) dextran sulfate (DxS), lipopolysaccharide from E. coli (LPS), and Epstein Barr virus (EBV). Patients with blood lymphocytes that showed a high spontaneous or PBA-induced 3H-thymidine uptake in 4 d [day] cultures had a significantly shorter therapy-free survival than patients whose lymphocytes showed a low thymidine uptake. The DxS-induced cellular thymidine uptake was the most powerful predictor of prognosis. Eighteen patients with leukemic cells responding to DxS stimulation had a median therapy-free survival of 17 mo. and a probability of 5 yr therapy-free survival of < 0.1, whereas for 30 patients with DxS unresponsive cells the corresponding figures were > 120 mo. and > 0.7, respectively (log rank, P < 0.0001). A multivariate Cox''s regression analysis revealed that the DxS-induced leukemic cell response was of greater prognostic importance than clinical features such as blood counts and staging according to Rai and Binet. PBA-induced leukemic cell thymidine uptake seems valuable in the prediction of prognosis in B-CLL.