Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Cytotoxic effect of dibutyryl camp, phorbol 12 myristate 13 acetate and lipopolysaccharide, but not interferon gamma, on promonocytic cell lines in vitro

Abstract

We studied whether inducers of cell differentiation alone could have cytotoxic effect on the promonocytic U937 and Mono Mac 6 cells in vitro. The cells were incubated with standard differentiating doses of interferon (IFN) gamma, dibutyryl cAMP (Bt2cAMP) or the phorbol ester phorbol 12 myristate 13 acetate (PMA), with or without lipopolysaccharide (LPS), and both protein synthesis and viability were examined. In both U937 and Mono Mac 6 cells the incorporation of [H 3]leucine was significantly reduced after PMA plus LPS stimulation, but not after IFN gamma stimulation, when compared with controls. For U937 cells there was also reduced incorporation after Bt2cAMP stimulation. Trypan blue exclusion experiments and the number of cells remaining in the cultures indicated that Bt2cBMP , PMB and/or LPS stimulated, but not IFN gamma stimulated, cells were less viable than unstimulated U937 or Mono Mac 6 cells. The results suggest that Bt2cAMP, PMA and LPS, but not IFN gamma, are cytotoxic towards promonocytic cancer cell lines in vitro.