A peptide antagonist derived from platelet-derived growth factor induces histamine release from rat peritoneal mast cells

A synthetic peptide (AMFLVWEIVRKKP) designed from the platelet-derived growth factor (PDGF) B-chain, which is known to act as a PDGF antagonist, induced histamine release from rat peritoneal mast cells. Maximal release by the peptide reached about 50% of the total histamine content in mast cells and half-maximal release occurred at 15 mu M. The histamine release induced by the PDGF antagonist was required for the presence of Ca2+ in the medium. Treatment of kinase inhibitors (staurosporine and genistein) with mast cells before exposure to the PDGF antagonist inhibited the release to some extent, while calmodulin antagonists (W-7 and R24571) had little effect. The PDGF antagonist induced the secretion of actin from mast cells concurrently with histamine release, though it had no effect on the distribution of tubulin. These results suggest the possibility that PDGF and its agonists may stimulate and induce exocytosis of peritoneal mast cells.