Different interaction of mast cells with human endothelial cells and fibroblasts.

In a number of chronic inflammatory conditions resulting in fibrosis, perivascular mononuclear cell infiltration including mast cells (MC) has been shown before the onset of vascular injury and interstitial fibrosis. These observations suggest a role for MC in inducing endothelial cell (EC) injury and fibroblast (FB) proliferation and collagen synthesis. In view of these observations, the interactions of MC with EC and FB were studied. MC adhesion to EC and FB showed time-dependent increase reaching a plateau at 1 and 3 hrs, respectively. With added MC, the proliferation of EC showed a dose-dependent decrease, but that of FB, a dose-dependent increase. MC, MC surpernatant and sonicated MC induced dose-dependent cytotoxic activity to EC, whose cytotoxicy was inhibited by trypsin inhibitor. FB cocultured with MC showed 9.95 times collagen synthesis and 11.0 times protein synthesis compared with FB without MC. These results showed that 1) MC attached to EC inhibited the proliferation by cytotoxic activity to EC, which was due to a kind of proteolytic enzyme involving trypsin, 2) MC had proliferative and collagen synthetic activity to FB. These results suggest the possibility that MC have a role in a number of chronic inflammatory diseases resulting in vascular injury and interstitial fibrosis.