We recently demonstrated that the colitogenic community of Nlrp6−/− mice, which contains P. intestinalis, alters susceptibility to DSS colitis via modulation of adaptive immune cells, i.e., transfer of the community in Rag2−/− mice was unable to exacerbate disease severity.32 To test whether P. intestinalis requires the presence of adaptive immune cells to alter colitis susceptibility, we colonized WT and Rag2-deficient mice with P. intestinalis. This evidence concerns the gene RAG2 and colitis.