Background: IL-23 is a pro-inflammatory cytokine belonging to the IL-12 cytokine family. IL-23 is essential for the
differentiation of T helper 17 (Th17) lymphocytes, a subtype of T lymphocyte implicated in chronic inflammatory/
autoimmune mediated diseases. Experimental models of arthritis and clinical indications have highlighted an important role
for Th17 lymphocytes in the pathogenesis of rheumatoid arthritis (RA). However the role and mechanism of action of IL23 in
the pathogenesis of RA are still not fully understood. Objective: This study was conducted to determine the serum
concentration of IL-23 in patients with RA as well as the relationship between the IL-23 level and disease activity. Methods:
The study included 35 patients with RA fulfilling the American College of Rheumatology (ACR) revised criteria for
diagnosis of RA as well as 15 age and sex matched healthy subjects as controls. The clinical parameters of disease activity
were determined by the 28-joint disease activity score (DAS-28). Erythrocyte sedimentation rate (ESR), C-reactive protein
(CRP), rheumatoid factor and Anti-citrullinated protein antibodies (ACPA) were done. The levels of IL-23 were determined
by enzyme-linked immunosorbent assay (ELISA). Results: Serum level of IL-23 was significantly elevated in RA patients
[43.6 (27.8-248.9)] compared to control group [32.1 (27.3-34.9)] (P <0.05). However, no correlations were found between
IL-23 and DAS-28 score, ESR or ACPA in RA patients. Conclusion: Our results imply that IL-23 may potentially play a role
in the pathogenesis of RA and may be a useful index for the diagnosis of this disease. Targeting the IL 23 cytokine may
provide a new therapeutic approach in the treatment of RA.