Effects of arsenic on blast transformation and DNA synthesis of human blood lymphocytes

Effects of inorganic arsenicals on DNA synthesis in unsensitized human bloo d lymphocytes were biphasic: the chemicals at very low concentrations enhan ced blast transformation and DNA synthesis, whereas higher concentrations i nhibited the transformation and DNA synthesis. The concentrations of arseni cals at which the maximum stimulating effect was found were 1 x 10(-5) M, 1 x 10(-6) M or 2 x 10(-6) M, and 0.8 x 10(-6) M or 1 x 10-6 M for sodium ar senite exposure of 1 h, 3 days and 6 days, respectively; for sodium arsenat e, 1 x 10(-5) M, 1 x 10(-5) M, and 2 x 10(-6) M or 5 x 10(-6) M, respective ly. Arsenicals must be present for the entire 6 days culture period to prod uce maximum stimulation of blast transformation of human lymphocytes. The l onger exposure of the lymphocytes to arsenicals, the lower the concentratio ns of arsenicals at which the maximum stimulating effect was found. The sti mulating effect of trivalent arsenic (sodium arsenite) was stronger than pe ntavalent arsenic (sodium arsenate). (C) 2000 Elsevier Science Ltd. All rig hts reserved.