Lactobacillus reuteri induces gut intraepithelial CD4+CD8αα+ T cells

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Science  25 Aug 2017:
Vol. 357, Issue 6353, pp. 806-810
DOI: 10.1126/science.aah5825

Tolerogenic T cells need probiotics

CD4+CD8αα+ double-positive intraepithelial lymphocytes (DP IELs) are a recently discovered class of intestinal T cells believed to take part in a variety of immune responses, including oral tolerance. These cells are absent in germ-free mice, but the mechanisms driving their development are unclear. Cervantes-Barragan et al. found that a particular species of probiotic bacteria, Lactobacillus reuteri, induces DP IELs. This does not occur by stimulating the immune system directly. Instead, L. reuteri generates a specific derivative of dietary tryptophan that promotes differentiation of DP IEL precursors. These findings underscore the delicate interplay between benign bacteria, diet, and gut health.

Science, this issue p. 806