Objective: To determine whether serum interleukin 6 (IL-6), oncostatin M (OSM), soluble IL-6 receptor (sIL-6R), and soluble gp130 (sgp130) levels in patients with systemic sclerosis (SSc) are elevated and whether they are correlated with the clinical or serological features of the disease.
Methods: Serum samples from patients with SSc (n = 55) and control subjects (n = 20) were investigated by ELISA. Patients were divided into 4 groups: 12 with limited cutaneous SSc (lSSc) < or = 3 years' duration (early lSSc), 22 with lSSc > 3 years' duration (late lSSc), 9 with diffuse cutaneous SSc (dSSc) < or = 3 years' duration (early dSSc), and 12 with dSSc > 3 years' duration (late dSSc).
Results: Serum IL-6 levels were significantly elevated in patients with early dSSc compared with controls. In addition, serum IL-6 was detected more frequently in patients with pulmonary fibrosis, and these values were inversely correlated with the percentage of vital capacity of individual patients. Furthermore, serum IL-6 levels were correlated with erythrocyte sedimentation rates, C-reactive protein, and IgG and IgA levels in patients. Serum sIL-6R levels were significantly higher in patients with lSSc versus controls. Serum OSM and sgp130 levels were not significantly elevated in patients with SSc compared with controls.
Conclusion: We suggest that IL-6 and sIL-6R may contribute to the disease process in SSc. In particular, IL-6 may be related to the early phase of the disease and the development of pulmonary fibrosis in SSc.