Effects of degranulation of mast cells on proliferation of mesenchymal cells in the mesentery of mice.

A mast-cell activator, compound 48/80, causes proliferation of mesenchymal cells in the mesentery of rats. Its effect on W/Wv mice deficient in mast cells was tested to determine whether the proliferation is mediated in the degranulation of mast cells. Incorporation of [3H]thymidine into mesenchymal cells in the mesentery of these mice with or without compound 48/80 was very small compared to their normal litter mates. However, bone marrow transplantation markedly enhanced the effect of compound 48/80, and resulted in an incorporation of [3H]thymidine almost comparable to that observed in normal mice. Our results provide evidence that mesenchymal cell proliferation is caused by a product secreted by mast cells when stimulated by compound 48/80.