Bradykinin sensitization of CSF-1-responsive murine mononuclear phagocyte precursors to prostaglandin E.

Bradykinin (BK) inhibited clonal proliferation of CSF-1-stimulated mononuclear phagocyte precursors derived from murine marrow. This inhibitory effect of BK was restricted to the subpopulation of precursors that required two signals, CSF-1 and LPS, for clonal proliferation. No effect was observed on stimulated colony formation by precursors that responded solely to the addition of CSF-1. Inhibition of colony formation by the two signal-dependent precursors required the presence of adherent marrow cells and was mediated by endogenously produced PG. Although evidence was obtained indicating that BK augmented PG production by adherent cells, an additional effect of BK appeared to be a significant sensitization of the two signal-dependent precursors to inhibition by PGE.