Moreover, the severity of arthritis and bone erosions were ameliorated by suppressing the serum inflammatory cytokines and the synovium cytokine mRNA expressions (especially those of IL-18, IFN-γ, TNF, and IL-6) and by the suppression of an accumulation of CD4+ T cells and F4/80+ cells in IL-18Rα KO mice. The gene discussed is IL18R1; the disease is arthritic joint disease.