Changes in colonic tissue levels of inflammatory mediators in a guinea-pig model of immune colitis.

An immune colitis based on a delayed-type hypersensitivity reaction was induced in dinitrochlorobenzene (DNCB)-sensitized guinea-pigs by intrarectal challenge with DNCB. A low challenge dose (0.25% DNCB) induced mild inflammatory changes in the distal colon and rectum characterized by goblet cell depletion. A higher challenge concentration (5% DNCB) resulted in severe colonic ulceration with crypt abscess formation. The inflammatory mediators, histamine, 5-hydroxytryptamine (5HT), glandular kallikrein and PGE2 were measured in freeze-dried colonic mucosae. Histamine content was three times control (p less than 0.01) in 0.25% DNCB induced colitis, although no significant change was observed in 5% DNCB challenged animals. Mucosal 5HT content was significantly reduced (p less than 0.01) after both challenges. Glandular kallikrein content did not differ from control, while PGE2 was significantly (p less than 0.05) increased at both challenge doses. The possible significance of these changes with respect to severity of inflammation and aetiology of colitis is discussed.