CD4 and rheumatoid arthritis: In contrast to these potential pro-inflammatory and immunogenic functions, CD4+ Th17 cells but not γδ T cells, were found in apposition to tartrate-resistant acid phosphatase positive osteoclasts in subchondral areas of inflamed joints in mice with collagen induced arthritis (CIA), and this pattern was reproduced in synovial biopsies of patients with RA [44].