STEM-CELL FACTOR CONTRIBUTES TO INTESTINAL MUCOSAL MAST-CELL HYPERPLASIA IN RATS INFECTED WITH NIPPOSTRONGYLUS-BRASILIENSIS OR TRICHINELLA-SPIRALIS, BUT ANTI-STEM CELL FACTOR TREATMENT DECREASES PARASITE EGG-PRODUCTION DURING N-BRASILIENSIS INFECTION

We assessed the effects of the c-kit ligand, stem cell factor (SCF), i n the jejunal mucosal mast cell hyperplasia that occurs during infecti on with the intestinal nematodes, Nippostrongylus brasiliensis or Tric hinella spiralis in rats. Compared with vehicle-treated rats, rats tre ated with SCF (25 mu g/kg/d, intravenous [IV] for 14 days) during N br asiliensis infection exhibited significantly higher levels of the rat mucosal mast cell (MMC)-associated protease, rat mast cell protease II (RMCP II) in the jejunum and serum on day 8 of infection, but not on days 10 or 15 of infection. By contrast, in comparison to rats treated with normal sheep IgG, rats treated with a polyclonal sheep antirat S CF antibody exhibited markedly decreased numbers of jejunal MMCs, leve ls of jejunal RMCP II, and serum concentrations of RMCP II during infe ction with either nematode, particularly at the earlier intervals of i nfection (less than or equal to day 10). Taken together, these finding s indicate that SCF importantly contributes to MMC hyperplasia and/or survival during N brasiliensis or T spiralis infection in rats, but th at levels of endogenous SCF are adequate to sustain near maximal MMC h yperplasia during infection with these nematodes. Notably, treatment o f rats with SCF somewhat increased, and treatment with anti-SCF signif icantly decreased, parasite egg production during N brasiliensis infec tion. This finding raises the interesting possibility that certain act ivities of intestinal MMCs may contribute to parasite fecundity during infection with this nematode. (C) 1995 by The American Society of Hem atology.