ABSTRACT
Several cytokines play a role in the production of autoantibodies and the pathogenesis of rheumatic diseases including systemic lupus erythematosus [SLE], rheumatoid arthritis [RA] and systemic sclerosis [SS]. This study investigated serum concentration of the proinflammatory Th[1] cytokine; IL[18] and its inducer IFN[gamma], the study also investigated serum concentration of proinflammatory Th[2] cytokine; IL[13], to explain the role of Th[1] and Th[2] in the pathogenesis of autoimmune rheumatic diseases [SLE, RA and SS]. IL[18], IFN[gamma] and IL[13] levels were evaluated by enzyme linked immunosorbent assay [ELISA]. Four groups were included in this study. Group I: Comprised [15] patients of SLE. Group II: Comprised [15] patients of RA. Group III: Comprised [15] patients with SS. Group IV: Control group consisted of [15] sex and age matched healthy controls. Serum levels of IL[18] was significantly higher in SLE [3138.200 +/- 1413.096 pg/ml] and RA [3336.667 +/- 921.839 pg/ml] than control group [86.647 +/- 35.370 pg/ml], while IL[18] in SS had no statistically significant difference between patients [103.634 +/- 50.593 pg/ml] and control group [86.647 +/- 35.370 pg/ml].The cut off level was 257.75 pg/ml. IFN[gamma] was significantly higher in SLE patients [5.439 +/- 1.430 lU/ml] and RA patients [2.973 +/- 0.598 lU/ml] than control group [0.580 +/- 0.234 lU/ml] ,while IFN[gamma] in SS had no statistically significant difference [0.592 +/- 0.245IU/ml] than control group [0.580 +/- 0.234 lU/ml] .The cut offlevelwasl.2IU/ml. As regard IL[13] it was significantly higher in SLE patients [55.673 +/- 6.892 pg/ml] ,RA patients [59.587 +/- 12.183 pg/ml] and SS [61.550 +/- 12.047 pg/ml] than control group [21.427 +/- 7.274 pg/ml] .The cut off level was 44.4 pg/ml .There was significant positive correlation of IL[18]/ IL[13] and IFN[gamma] / IL[13] ratio in SLE and RA, while significant negative correlation of IL[18]/IL[13] and IFN[gamma]/IL[13] ratio in SS. There was a significant increase of both Th[1] cytokines [IL[18] and IFNgamma and Th[2] cytokine [IL[13] in SLE and RA with Th[1] predominance,while predominance of Th[2] cytokine [IL[13] in SS than Th[1]i cytokine [IL[18] and IFN[gamma]. This result suggests that IL[18], INF[gamma] and IL[13] could be involved in the pathogenesis of autoimmune rheumatic diseases