Effect of SLE on IL-12 level as compared with other autoimmune rheumatic diseases

ABSTRACT

IL-12 is a proinflammatory cytokine produced by different antigen presenting cells. It has been shown to exert a critical role in inducing Th1 phenotype, thus initiating cell-mediated immune responses, but the significance of IL- 12 in rheumatic diseases is not clear. To determine IL-12 serum levels in autoimmune rheumatic diseases and to analyze the relationship of this cytokine with main clinical and laboratory parameters. We analyzed, by ELISA, serum IL-12 levels in 109 patients with Systemic Lupus Erythematosus [SLE], 42 with Sjogren Syndrome [SS], 27 with Systemic Sclerosis [Scl], 79 with Rheumatoid Arthritis [RA], 40 with Psoriatic Arthritis [PA] and 20 healthy controls. We also examined main clinical and laboratory parameters, including autoantibody profile and clinical indices of disease activity. IL-12 serum levels were significantly higher in SLE and SS patients in respect to controls. IL-12 serum levels were significantly higher in SLE patients as compared to those suffering from RA, PsA and Scl. When we evaluated disease activity in SLE patients, we found significantly higher IL-12 serum levels in subjects without renal involvement, while no correlation was found in the other rheumatic autoimmune diseases. These findings suggest that IL-12, modulating cell and humoral immune responses, are involved in the pathogenesis of autoimmune rheumatic diseases, such as SLE and SS