UPTAKE OF INGESTED PROTEINS FROM THE RAT CUT DURING A LOCALLY-INDUCED HYPERSENSITIVITY REACTION EVIDENCED BY RELEASE OF RAT MAST CELL PROTESE II

Abstract

Hypersensitivity reactions to dietary proteins may lead to an increased permeability of the gut to macromolecular antigen molecules and thereby contribute to further sensitization. Rats sensitized to ovalbumin (OA) were tube-fed 1g of bovine serum albumin (BSA) and challenged one hour later with 100mg OA introduced directly into the jejunum. Serum samples taken after challenge were analysed for BSA by RIA, and for rat mast cell protease II (RMCP II), a specific marker for mucosal mast cell degranulation, by ELISA. One hour after antigen challenge the levels of RMCP II in the sera of challenged rats were significantly higher than both the pre-challenge levels and those of sham-challenged controls (p<0.002). There was no correlation between RMCP II levels and BSA levels in the challenged rats. We conclude that local hypersensitivity reactions in the rat gut may be unequivocally demonstrated by RMCP II release. However, a concomitant increased uptake of “bystander” antigen is not a consistent finding. A role for such an increased uptake in the aetiology of dietary intolerance is not supported by those results.