Regulatory T cells link food and the immune system.

Professor Shimon Sakaguchi received the 2025 Nobel Prize in Physiology or Medicine for his discovery and elucidation of regulatory T cells (Tregs). This review celebrates his achievement by discussing the important role of Tregs in immune responses to food. Tregs, which primarily differentiate in the thymus, are integral to suppressing immune reactions to self antigens and thus maintaining self tolerance. In addition, peripheral Tregs may differentiate in other sites, namely the intestinal immune system. Immune tolerance may be established to orally ingested antigen, termed oral tolerance, and Tregs induced in the intestinal immune system are involved. In addition, Tregs mediate immunomodulation by food, such as the alleviation of pollinosis, and may be involved in suppressing inflammation in other situations. This review also addresses the mechanisms, including those mediated by dendritic cells.