We thus examined the role of ILC3s in periodontitis pathogenesis by measuring ligature-induced gingival defects and alveolar bone resorption in Rag2-/- mice, which lack functional B, Th, and Tc cells, and Rag2–IL-2 receptor common gamma (Il2rg) double-knockout mice, lacking all lymphocytes including ILCs. The gene discussed is RAG2; the disease is periodontitis.