RAG1 and necrotizing enterocolitis: Importantly, infiltrating pro-inflammatory T cells are primary instigators in NEC development.216 Evidence suggests that the adoptive transfer of mucosal CD4+ T cells, activated by NEC, into naive mice spontaneously induces intestinal inflammation.92 However, lymphocyte-deficient Rag1–/– mice, lacking both T and B cells, are protected from NEC development.