Singh, R., et al. - Data on synovial fluid (SF) cytokine concentrations in patients with reactive arthritis (ReA) or undifferentiated spondyloarthropathy (uSpA) are limited and contradictory...Increased IL-17, IL-6, TGF-beta, and IFN-g concentrations in ReA/uSpA than in RA suggest that Th1 and Th17 cells could be the major agents in inflammation in ReA/uSpA