[Effect of the ionophore antibiotic valinomycin on the lymphocyte blast-transformation reaction induced by phytohemagglutinin].

The effect of valinomycin on blast-transformation of human lymphocytes has been studied. The lymphocyte response was assayed by incorporation of radioactive precursor into DNA. DNA synthesis by PHA-stimulated lymphocytes was inhibited by valinomycin at concentration of 10(-8) M. The effect of high concentrations of valinomycin on the cells appeared to be irreversible. Excess of potassium in the medium was not effective in preventing the inhibitory action of valinomycin. An extensive washing of cells did not result in any release of the bound drug in the 10(-8) M concentration. The results are consistent with a hypothesis that lymphocyte stimulation is critically dependent on the level of intracellular K+.