IL17A and rheumatoid arthritis: From a clinical point of view, we believe that the levels of IL-17 induced by IL-23 in our experiment would significantly affect osteoclastogenesis in patients with RA because the concentrations of IL-17 in synovial fluid and culture medium of synovial tissue obtained from patients were less than 14 pg/ml and 40 pg/ml, respectively, in a previous study [21].