Although up to 55% of the KO-Rag−/− mice developed arthritis, in contrast to the CD11c-Flip-KO mice, the arthritis in the KO-Rag−/− mice was significantly (P<0.05–0.001, unpaired two-sided t-test) less severe, and in some mice the arthritis spontaneously improved or resolved by 21–22 weeks (Fig. 7a). This evidence concerns the gene CFLAR and arthritic joint disease.