Altered expression of mast cell proteases in the rat. Quantitative and immunohistochemical analysis of the distribution of rat mast cell proteases I and II during helminth infection.

Expression of mast cell granule protease is regulated in a tissue-specific fashion in the rat. The granule chymases rat mast cell proteases I and II (RMCP I and II) predominate in non-mucosal and mucosal sites, respectively. Intestinal mastocytosis, a T cell-mediated phenomenon associated with enteric nematodiasis, is accompanied by massive local expression of RMCP II and by release of this protease systemically into blood. The present observations, where both RMCP I and II have been quantified by ELISA and immunolocalized by paired fluorescence, show that the expression of both proteases in parasitized rats is profoundly altered at sites distant from infection. Thus, RMCP II-containing cells are recruited to liver and thymus, and in the thymus there is a > 2-fold increase in concentration of RMCP I. The latter protease is depleted from bone marrow and mesenteric lymph node early during infection, but concentrations of RMCP I in trachea/larynx, lung, and skeletal and cardiac muscle are increased. Increased mast cell counts in intestine, lung and liver are highly correlated with tissue concentrations of RMCP II.