IL-22 in SF and serum of PsA and RA were elevated compared to OA patients. Synovial fluid (SF) and peripheral blood (PB) were collected from psoriatic arthritis (PsA, n = 15), rheumatoid arthritis (RA, n = 15) and osteoarthritis (OA, n = 15) patients. IL-22 levels were measured in SF and serum samples by ELISA. All experiments were done in triplicate. Results were expressed as Mean ± SEM. Nonparametric tests; Mann Whitney and Kruskal Wallis ANOVA with Dunn's multiple comparison tests were used to determine statistical significance.