PerspectiveImmunology

How does the immune system tolerate food?

Science  19 Feb 2016:
Vol. 351, Issue 6275, pp. 810-811
DOI: 10.1126/science.aaf2167

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Summary

The gastrointestinal immune system (gut-associated lymphoid tissue) has the unique capacity to discriminate between harmless and potentially dangerous material. It can raise a protective response against pathogenic microbes and toxins while tolerating food antigens and commensal microbes. This is a challenge given the vast number of foreign antigens, mainly derived from food (>100 g of protein per day), and commensal microbes colonizing the gut (an estimated 100 trillion, 10 times the number of cells in the human body). Dysfunction of this delicate balance between immunity and tolerance can lead to pathologies such as food allergy, autoimmune diseases, and infections. On page 858 of this issue, Kim et al. (1) show that dietary antigens trigger the generation of a regulatory T (Treg) cell type in the small intestine that suppresses immune responses to food. These Treg cells are phenotypically and functionally distinct from those in the colon that suppress immune responses to commensal microbes (2, 3).