Temporal distribution of distinct mast cell phenotypes during intestinal schistosomiasis in mice.

Mastocytosis is a common feature of helminth infection in most host species. We examined the temporal distribution and phenotype of mast cells during intestinal schistosomiasis in mice, using antibodies directed against histamine, a general mast cell marker, against mouse mast cell protease-1 (MMCP-1), a mucosal mast cell (MMC) marker, and against tryptase, a predominantly connective tissue mast cell (CTMC) marker. Ileal paraffin and/or cryosections of control, 8- and 15-week-infected mice were quantitatively analysed. In the intestinal wall of non- and unisexual infected mice, a few dispersed mast cells were detected. In infected mice, a transient increase of mast cells in the mucosa and a gradual increase in the outer muscle layer were observed. MMCP-1 expressing MMCs were predominantly present in the mucosa during the acute phase [8 weeks postinfection (p.i.)], while tryptase and histamine immunoreactivity demonstrated that two subsets of CTMCs were predominantly present in the outer muscle layer at 15 weeks p.i. (chronic phase). In conclusion, these results reveal that, in mice, both MMCs and CTMCs are involved in the inflammatory response during schistosomiasis. The recruitment of each mast cell population is time-dependent and occurs at different locations. These data suggest that mastocytosis is associated with motility-related gastrointestinal symptoms and egg excretion.