Interferon-λ Mediates Oral Tolerance and Inhibits Antigen-Specific, T-Helper 2 Cell–Mediated Inflammation in Mouse Intestine

Background & Aims Oral tolerance is an important component of gastrointestinal homeostasis, but mechanisms of its development are not fully understood. Loss of oral tolerance occurs during food allergen–related inflammation in the gastrointestinal tract. Interferon (IFN)-λ regulates immunity, but its role in oral tolerance is not clear. We investigated the role and the mechanism of IFN-λ in the development of oral tolerance and its effect on antigen-induced, T-helper (Th)-2 cell–mediated inflammation in the intestine. Methods Expression of IFN-λ and its receptor were analyzed by immunohistochemical, flow cytometric, or immunoblot analyses. Tolerogenic dendritic cells (DCs) and regulatory T cells were examined in vitro and in vivo. A mouse model of antigen-induced, Th2 cell–mediated intestinal inflammation was used to examine the role of IFN-λ and T cells in oral tolerance in the intestine. Results CD3+ cells expressed the IFN-λ receptor, which was up-regulated following antigen-specific or nonspecific activation. Interaction between IFN-λ and its receptor induced apoptosis of T cells and their subsequent phagocytosis by DCs. This led to the generation of tolerogenic DCs and T regulatory cells in vitro and in vivo. Passive transfer of IFN-λ–primed CD3+ cells inhibited Th2 cell–mediated inflammation in the intestine. Conclusions IFN-λ is involved in development and maintenance of oral tolerance in the intestines of mice; it might be used to suppress antigen-specific Th2 cell–mediated inflammation in patients.