Immune cells in the gut act as an unexpected shield against inflammation

Follicular helper T (TFH) cells, long known for helping B cells produce antibodies, also play a surprising role in keeping the immune system calm in the gut, according to a study published in Nature Immunology on 21 October 2026. Shivangi Dave, Holly Bachus and colleagues in André Ballesteros-Tato’s laboratory report that a subset of TFH cells produces interleukin-2 (IL-2), a key immune signalling molecule, at the border between T cells and B cells and within interfollicular regions of gut-associated lymphoid tissues (GALT). This locally delivered IL-2 appears essential for maintaining the population of regulatory T (Treg) cells, the immune cells that suppress inappropriate immune responses.

Using mouse models in which IL-2-producing TFH cells were selectively depleted or genetically ablated, the researchers found that GALT Treg cell maintenance was disrupted and effector T cell activation became uncontrolled. Mice lacking this IL-2 supply developed colitis and fatal multiorgan inflammation. The team’s figures trace this progression step by step: TFH cells and Treg cells share niches in the GALT, TFH cell deficiency destabilises Treg cell maintenance, and the balance of Treg cell subsets shifts from a protective to a pathogenic state when TFH cell-derived IL-2 is absent.

A striking clue to the mechanism came from antibiotic treatment. When mice lacking IL-2-producing TFH cells were given broad-spectrum antibiotics, both intestinal and extraintestinal pathology were alleviated. The authors interpret this as evidence that loss of tolerance to commensal-derived antigens, the microbes that normally live harmlessly in the gut, is a key driver of the disease observed in these animals. In other words, without the local IL-2 niche, the immune system loses its ability to remain tolerant to the gut’s resident microbial community, and the resulting inflammatory response spills beyond the intestine.

Importantly, the study shows that this TFH cell function is independent of B cells, distinguishing it from the cells’ well-characterised role in supporting antibody responses. The findings define what the authors call a spatially restricted TFH cell-derived IL-2 niche that is critical for Treg cell stability in gut-associated lymphoid tissues and reveal an immunoregulatory role for TFH cells in maintaining gastrointestinal tolerance. The work was conducted in mice, so its implications for human intestinal immunity and inflammatory disease remain to be established. The full study is available behind a subscription paywall at Nature Immunology, with the abstract and figure summaries publicly accessible.

Subject of Research: The role of IL-2-producing follicular helper T cells in maintaining regulatory T cell homeostasis and immune tolerance in gut-associated lymphoid tissues.

Article Title: IL-2-producing TFH cells sustain Treg cell homeostasis and immune tolerance in the gut

Article References: Dave, S., Bachus, H., Santiago, N., Meloun, A., Smelkinson, M., Foote, J. B., Hill, T., Fucile, C., Rosenberg, A. F., & Ballesteros-Tato, A. (2026). IL-2-producing TFH cells sustain Treg cell homeostasis and immune tolerance in the gut. Nature Immunology, 27(11), 2267-2279. https://doi.org/10.1038/s41590-026-02690-5

Image Credits: AI Generated

DOI: 10.1038/s41590-026-02690-5

Keywords: TFH cells, IL-2, regulatory T cells, gut-associated lymphoid tissues, immune tolerance, colitis, commensal microbes, T cell–B cell border, multiorgan inflammation, Nature Immunology, mouse models, immunology