Tuft cells have long been a mysterious component of the intestinal epithelium. Related papers by two groups in Nature and one group in Science demonstrate important roles for tuft cells in sensing and responding to intestinal protozoa and helminth parasites. Tuft cells normally make up a small fraction of the intestinal epithelium, but after exposure to parasites, they substantially increase in number and release copious amounts of interleukin 25 (IL-25). That IL-25, in turn, activates group 2 innate lymphoid cells, which then drive a type 2 immune response characterized by IL-13, eosinophila and mucus production; these collectively lead to expulsion of the parasite. Deletion of tuft cells or ablation of their chemosensory function by knockout of the cation channel TRPM5 impairs the type 2 response and parasite expulsion. This demonstration that tuft cells are prominent IL-25 producers indicates a key role for these cells in the initiation of type 2 immune responses in the small intestine.

Nature 529, 221–225 & 226–230 (2016);

Science (4 February 2016) doi:10.1126/science.aaf1648