Proinflammatory Cytokines (IL-12 and IL-18) In Immune Rheumatic Diseases: Relation With Disease Activity and Autoantibodies Production

¹Youssef M. Mosaad ¹Shereen S. Metwally ¹Fatma A. Auf ¹Elham R. AbdEl-Samee ³Basem El-Deek ²Nabil I. Limon ¹Farha A. El-Chennawi

¹Clinical Immunology Unit, Clinical Pathology Department, ²Rheumatology Unit, Internal Medicine Department and ³Community Medicine & Biostatistics Department, Mansoura Faculty of Medicine, Mansoura University, Mansoura, Egypt.

Interleukin-18 (IL-18) and its inducer IL-12 have multiple biological activities that are important in generating Th1 responses and inflammatory tissue damage. We investigated serum concentration of the novel pro-inflammatory Th1 cytokine; IL-18, and its inducer IL-12 in patients with immune rheumatic diseases. Group I comprised32 patients of systemic lupus erythmatosus (SLE), Group II comprised 36 patients of rheumatoid arthritis (RA). Group III comprised 9 patients (2 patients of Behcet, 2 patients of Dermatomyositis, 2 patients of Sicca syndrome, one patient of Scleroderma, and 2 patients of Mixed connective tissue disease). Group IV is a control group consists of 21 sex and age matched healthy subjects and correlated their levels with autoantibody concentration (ANA and ds-DNA), clinical grades and SLE disease activity index (SLEDAI). Serum IL-18,IL-12 ,ANA and ds-DNA were measured by enzyme immuno sorbent assay. IL-18, IL-12 and ANA were significantly higher in the three studied groups than in the control group (IL-18; P<0.001 in the three groups, IL-12; P=0.019, P=0.002, and P= 0.006, and ANA; P<0.001, P=0.002,and P=0.006, respectively).ds-DNA was significantly higher in SLE patients than in control group (P<0.001).There were significant positive correlations between; A) levels of IL-18,and both ANA and ds-DNA in SLE patient (r=0.41,P=0.001,r= 0.58 and P=0.001 respectively); and B) IL-18 and ANA in both RA and group III patients (r= 0.32,P=0.005,r=0.61and P= 0.022 respectively).Also ,there were significant positive correlation between the levels of IL-18 and clinical grades of the three groups (r=0.60,P=0.001, r=0.79,P=0.001,r=0.78 and P= 0.001 respectively).In SLE patients ,IL-18 concentration shows significant positive correlation with SLEDAI score (r= 0.76 ,P=0.001).In conclusion, the elevation of proinflammatory cytokines (IL-18 and IL-12 ) may trigger the inflammatory process in immune rheumatic diseases and IL-18 is correlated with disease activity.