Biphasic and differential effects of the cytostatic agents avarone and avarol on DNA metabolism of human and murine T and B lymphocytes.

The two novel antimitotic and potent antileukemic agents avarone and avarol were determined to inhibit the [3H]-dThd incorporation rates of both murine spleen and human peripheral blood lymphocytes within the concentration range of 2-6 microM. The mitogens concanavalin A (ConA; for T lymphocytes), lipopolysaccharide (LPS; for murine B lymphocytes) and pokeweed mitogen (PWM; for human T and B lymphocytes) were used to stimulate DNA synthesis in the lymphocyte fractions. The ED50 concentrations, causing a 50% reduction of [3H]-dThd incorporation, were significantly lower in the experiments with avarone than in those with avarol. Moreover it was established that the DNA synthesis of ConA-activated lymphocytes was more sensitively inhibited by the compounds than that of LPS or PWM-activated cells, or non-activated cells. In addition it was elucidated that at low concentrations (1-2 microM) avarone and avarol caused a stimulation of dThd incorporation only in LPS or PWM-activated lymphocytes. Based on these results it is assumed that both antileukemic agents also affect differentially the different hematologic neoplasms.