As imbalance between Th17 and Treg cells has been identified as playing a crucial role in RA pathogenesis [24], we investigated whether the populations of Th17 and Treg cells were altered in A77 1726-treated IL-1Ra-KO mice, IL-17-expressing (mainly Th17) and CD25+ Foxp3+ (mainly Treg) CD4+ T cells were analyzed by confocal microscopy. This evidence concerns the gene CD4 and rheumatoid arthritis.