Serum levels of soluble TNF alpha receptor type I and the severity of systemic sclerosis

Several abnormalities of cytokines have been shown to occur in systemic scleroderma; however their correlation with clinical parameters is controversial. Since serum concentrations of cytokine receptors have been shown to correlate with inflammatory processes, including systemic sclerosis, the aim of our study was to compare serum concentrations of TNF alpha receptor type 1 with the concentrations of soluble intercellular adhesion molecule-1 (sICAM-1), soluble interleukin-2 receptor (sIL-2R) and aminoterminal propeptide of procollagen type III (PIII NP). The findings were correlated with the clinical parameters and antibody patterns, and with the disease severity. Serum samples were studied with the use of enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA) for sTNF alpha R1, sICAM-1, sIL-2R and PIII NP. The series comprised 36 patients with systemic scleroderma: 13 with diffuse variety and 23 with limited variety, and 7 with Raynaud's disease. Healthy volunteers (n = 25) were chosen from doctors and/or other laboratory staff. Increased levels of sTNF alpha-receptor type 1 were found in 77% of patients with diffuse variety and in only 30% of patients with limited form. Increased serum concentrations in patients with diffuse scleroderma and limited variety were found for sICAM-1 54% and 65%, for sIL-2R 46% and 15%, and for PIIINP 77% and 50%, respectively. There were significant correlations between serum levels of sTNF alpha-receptor type 1 and PIIINP (r = 0.653, p < 0.0001), and sTNF alpha-receptor type 1 and sIL-2R (r = 0.625, p < 0.0001), but not between sTNF alpha-receptor type 1 and sICAM-1 (r = 0.127, p < 0.526). Clinical analysis revealed that serum concentrations of sTNF alpha-RI seem to correlate best with the severity of the disease and, as the only parameter, correlated with lung involvement. The study showed that, in addition to recognized parameters of scleroderma severity (IL-2R, PIIINP), a new important marker appears to be sTNF alpha-receptor type 1.