Correlation between Relative Expression of IL 17 and PERP in Rheumatoid Arthritis Patients and Disease Activity Abstract Background: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder. Decreased apoptosis is considered an important leading cause of autoimmune diseases. As IL17 and PERP can affect apoptosis process, they may contribute the pathogenesis and activity of RA. Objectives of this study were to investigate the possible correlation of IL 17 and PERP levels with RA pathogenesis and activity. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from fifty RA patients and fifty healthy subjects; RNA was extracted and subjected to real time PCR to detect the relative expression of IL17 and PERP. Results: IL17 and PERP mRNA expression levels were correlated with RA disease activity parameters. Increased IL17 and decreased PERP mRNA expression levels were detected in patients as compared to the healthy controls (P˂0.001) and they were positively and inversely correlated with disease activity score for 28 joints (DAS28), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and rheumatoid factor (RF). A significant negative correlation between PERP and IL-17 mRNA expression levels was found (P ˂0.001). In conclusion, increased level of IL 17 and decreased and decreased level of PERP may constitute two major factors in the pathogenesis and activity of RA.