RAG1 and gastrointestinal disease: Adoptive transfer of CD4+ T cells from mice whose ILC3s did not express MHCII (but not CD4+ T cells from wild type (WT) mice with intact ILC3-intrinsic MHCII expression) were able to drive the development of gastrointestinal disease in RAG1−/− mice but not germfree RAG1−/− mice, indicating that aberrant CD4+ T cell activation due to MHCII-deficiency in ILC3s was a microbiota-dependent phenomenon.