Proteinase phenotypes and fixation properties of rat mast cells in parasitic lesions caused by Mesocestoides corti: selective and site-specific recruitment of mast cell subsets.

The distribution, fixation properties, and protease phenotypes of mast cells populating lesions caused by the metacestode stage of the cestode Mesocestoides corti in the rat were characterized. Intraperitoneal infection with M. corti induced severe granulomatous types of reactions around the pancreas and further lesions in the liver. These sites were infiltrated with mast cells which contained either rat mast cell protease I or II derived respectively from connective tissue (CTMC) or mucosal mast cells (MMC). A proportion of cells in pancreatic granulomas had staining and fixation properties identical to those of intestinal mucosal mast cells; others were typical connective tissue mast cells. Subcutaneous inoculation of parasites was associated with nodular dermal reactions, and all of the infiltrating mast cells had the fixation and staining properties of CTMC and contained RMCPI uniquely. Increased numbers of RMCPII-containing mast cells were present in the intestines of rats infected intraperitoneally. Significant quantities of RMCPII were present in homogenates of pancreatic granulomas and in livers of rats harbouring intraperitoneal infections but none was detected in skin. These findings suggest that mast cells of different phenotypes are selectively recruited to some, but not all, lesions.