Altered mitogenic responsiveness of chronic leukemic lymphocytes and normal human lymphocytes treated with dimethyl...

Peripheral lymphocytes from patients with chronic lymphocytic leukemia display a delayed and lowered response to stimulation by PHA, as compared with the lymphocytes from normal donors. This response was determined by measuring the incorporation of tritiated thymidine. The addition of DMSO in concentrations of 0.1%, 0.25%, 0.5%, 1.0%, and 2.0% (v/v) to the culture fluid of normal cell cultures that had been stimulated, with PHA elicited a 3- to 4-fold increase in the rate of incorporation of labeled thymidine at the 3-day test period. The addition of 2.0% DMSO proved to be preferentially cytotoxic to cultures of leukemic cells after 48 hours, as compared with the virtual absence of cytotoxicity for cultures of normal lymphocytes. The addition of 0.1%, 0.25%, 0.5%, and 1.0% DMSO to cultures of leukemic cells stimulated with PHA (as were normal cell cultures) resulted in a 6- to 6.5-fold increase in the rate of uptake of tritiated thymidine at 3 days.