IFN-GAMMA ENHANCES MACROMOLECULAR TRANSPORT ACROSS PEYERS-PATCHES IN SUCKLING RATS - IMPLICATIONS FOR NATURAL IMMUNE-RESPONSES TO DIETARY ANTIGENS EARLY IN LIFE

Background: The capacity to generate (interferon-gamma) IFN-gamma, a p otent immunoregulatory and inflammatory cytokine, is low in neonates a nd deficient in patients with food allergy. Methods: We investigated t he effect of IFN-gamma on antigen transport in the gut. In experiment I rat pups were randomized into two groups at the age of 14 days i.e., before gut maturation: Group IFN was given intraperitoneally recombin ant rat IFN-gamma on days 14, 16, 18, 20. In experiment II, rats were randomized into two groups at the age of 26 days, i.e., after gut matu ration: Group IFN received the IFN-gamma treatment on days 26, 28, 30, 32. Controls in both experiments received sterile saline. The absorpt ion of horseradish peroxidase (HRP) across jejunal segments with and w ithout Peyer's patches was studied in Ussing chambers on days 21 and 3 3 for experiments I and II, respectively. Results: In experiment I, th e absorption of intact HRP across both types of segments was significa ntly increased in Group IFN compared to controls. The mean (95% confid ence interval) rate of degraded HRP absorption across patch-containing segments in Group IFN was significantly greater than in controls 4420 (3162-6179) ng.h(-1).cm(-2) in comparison to 1550 (633-3790) ng.h(-1) .cm(-2); F = 8.96, p = 0.009. Conclusion: IFN-gamma increases macromol ecular transport before gut maturation particularly across Peyer's pat ches. This Peyer's patch-targeted effect can be important eliciting mu cosal immune responses against dietary antigens early in life and aidi ng their immune exclusion. (C) 1997 Lippincott-Raven Publishers.