Immunological challenge causes mitogenic stimulation in normal connective tissue cells.

Because polyamine-induced mast-cell secretion causes mitogenesis in surrounding tissue cells in the rat mesentery, we studied whether an immunological challenge in guinea-pig and rat that normally involves mast-cell secretion caused mitogenesis in adjacent normal tissue cells. The appropriate antigen was injected intraperitoneally into pre-sensitized animals. Mast-cell secretion was assessed as histamine release and proliferation by estimating DNA synthesis and mitotic index in the mesentery of the intact animals. In both species the immunological challenge causing significant release of mast-cell histamine was followed by a marked mitogenic response in fibroblasts and mesothelial cells of the mesentery. Although the present study was not primarily designed to study the molecular mechanisms for stimulating cell proliferation, the results suggest that the role of primary mast-cell products on a quantitative basis is significantly different in the mitogenesis following immunological challenge than in polyamine-induced mast-cell mediated mitogenesis in the rat.