In vitro effect of an acute nonspecific inflammatory exudate on tritiated-thymidine incorporation by unstimulated and PHA-stimulated spleen cells.

The effect of an acute nonspecific inflammatory exudate with mitogenic activity for macrophages in culture has been tested on the spontaneous and PHA-induced DNA synthesis by spleen cells in vitro. Stimulatory effect of this exudate was observed on the spontaneous DNA synthesis which was detectable over a range of 1:4 to 1:4096 concentrations. After optimal PHA stimulation, an inhibition of mitogen-induced DNA synthesis was observed when the cells were exposed to the highest concentrations (up to 1:128) of the exudate. Thereafter, the phenomenon could be reversed and the stimulation was maximal at the concentration of 1:2048. When a suboptimal dose of PHA was used, the stimulatory effect was more pronounced and detected from 1:8 up to 1:4096 concentrations.