Abstract : Rheumatoid arthritis is an autoimmune systemic inflammatory disease primarily affecting the joints as well as other extra-articular tissues. This study was designed to evaluate the immunomodulatory effect of different doses of quercetin(500mg, 1000mg, 1500mg/day) for rheumatoid arthritis in patients treated with the conventional disease modifying antirheumatic drugs (DMARDs). This project was performed on 160 rheumatoid arthritis patients who fulfilled the American College of Rheumatology (ACR) criteria for the diagnosis of rheumatoid arthritis. In addition to 30 healthy volunteers were invited to participate in the study and served as a control group. The selected patients were allocated randomly into four groups, group (A) treated with azathioprine(100 mg/day) plus a placebo( starch containing capsules), group (B) treated with azathioprine (100mg/day) plus quercetin (500mg/day), group (C) treated with azathioprine (100mg/day) plus quercetin (1000mg/day) and group (D) patients treated with azathioprine (100mg/day) plus quercetin (1500mg/day). Serum level of interleukin-6, interleukin-10, intercellular adhesion molecule I (ICAM-1), complements proteins pretreatment and after eight weeks of treatment. It was found that quercetin at doses of 1500mg/ day, when added to 100mg azathioprine, significantly(p< 0.05) reduced interleukin-6, complement protein 3 (C3) & complement protein 4 (C4) levels and elevated interleukin-10 level more than when azathioprine had combined with placebo or with lower doses of quercetin(500, 1000mg). However, all of tested doses of quercetin in this study were able to significantly (p< 0.05) reduce the level of intercellular adhesion molecule-1 as compared to the quercetin-free treated group. Oral administration of different daily doses of quercetin (500, 1000, 1500mg) in combination with azathioprine (100 mg) produced an immunomodulatory action through the reduction of interleukin-6, intercellular adhesion molecule-1 and complement protein

Keyword : Immunomodulatory, Quercetin, Rheumatoid Arthritis, Interleukins, Complements protein.