Antigen-specific secretory IgA antibodies in the gut are decreased in a mouse model of food allergy

Background: A large body of evidence implicates IgA antibodies in the immune response to pathogens present in the gut. Whether IgA antibodies play a similar role in food allergy remains to be determined. Objective: We sought to characterize beta-lactoglobulin (BLG)-specific serum and secretory IgA antibody production in the gut and to define the role of antigen-induced cytokines in IgA production in a murine model of food allergy. Methods: BLG-specific IgA antibodies were measured in the sera and feces of mice anaphylactic or tolerant to BLG. The number of antibody-secreting cells in the spleen and Peyer's patches was determined by means of ELISPOT. Mesenteric lymph node cells and Peyer's patch T cells were transferred to naive mice, and antibody production in the sera and feces in recipient mice, as well as antibody-secreting cell numbers, were measured. Results: Serum IgA antibody titers were strongly increased in anaphylactic mice. In contrast, BLG-specific IgA antibody titers were increased in feces but not in sera from tolerant mice. These results were correlated with an increased number of BLG-specific IgA-secreting cells in Peyer's patches from tolerant mice. The adoptive transfer of Peyer's patch CD3(+) cells from tolerant mice induced an increased number of IgA-secreting cells preferentially in the Peyer's patches of naive recipient mice. Furthermore, an increase of BLG-induced IL-10 and TGF-beta levels was found at IgA production sites. Conclusions: These results suggest a role for secretory IgA in tolerance mechanisms to foods. Peyer's patch CD3(+) cells are primarily involved by favoring IgA production through the release of IL-10 and TGF-beta.