ANAPHYLACTIC COLONIC HYPERSECRETION IN COWS MILK SENSITIZED GUINEA-PIGS DEPENDS UPON RELEASE OF INTERLEUKIN-1, PROSTAGLANDINS AND MAST-CELLDEGRANULATION

Methods: The effect of beta-lactoglobulin (beta-LGI) challenge on net water movements into the proximal colon and the role of Interleukin-I (IL-1), prostaglandins and mast cell degranulation on the challenge-in duced net water changes were assessed in vivo using isolated colonic l oops in anaesthetized guinea-pigs immunized to bovine milk. Results: B eta-lactoglobulin challenge infused into the colonic loop during 30 mi n reversed the net water flux into a net secretion during the period o f antigen infusion. Doxantrazole, a mast cell stabilizing agent, admin istered 120 min before challenge infusion, suppressed challenge-induce d hypersecretion. Similarly recombinant IL-1 receptor antagonist prote in abolished the antigen-induced colonic secretory effect. Indomethaci n, a prostaglandin synthesis inhibitor, administered 20 min prior to a ntigen infusion, significantly (P < 0.05) reduced, but did not abolish , the challenge-induced colonic secretory effect. Conclusions: These r esults suggest that IL-1 plays an important role in antigen challenge- induced colonic hypersecretion which involves mast cell degranulation and prostaglandin release.