We then compared the infiltration of Th1 cells (IFN-γ+ CD4+), Th17 cells (IL-17+ CD4+), and Th22 cells (IFN-γ− IL-17− IL-22+ CD4+) in synovial tissues from patients with osteoarthritis (OA) and those with RA. The gene discussed is IL17A; the disease is osteoarthritis.