PRF1 and Crohn disease: All together, we identified an ILC1-like cell type that stably expresses high levels of the cytotoxic molecules granulysin and perforin, but not granzyme B. The observed expansion of these ILC1s in Crohn’s disease patients may be detrimental to the patients by enhancing inflammation but could also be beneficial by the killing of bacteria via granulysin secretion.