Objective: To evaluate the blood concentration of type III procollagen N-terminal propeptide (PIIINP), soluble interleukin-2 receptor (sIL-2R), and von Willebrand factor (vWF) in systemic sclerosis (SSc) patients.
Methods: PIIINP, sIL-2R, and vWF were measured in the sera and plasma of 29 SSc patients and 29 sex- and age-matched healthy controls. Serum PIIINP was determined by radioimmunoassay. Both serum sIL-2R and plasma vWF were measured by enzyme-linked immunosorbent assay (ELISA). Associations between concentrations and clinical and laboratory features were evaluated.
Results: Serum levels of PIIINP and sIL-2R were significantly higher in the SSc group than in the control group (p < 0.01 for both). No differences in serum PIIINP and sIL-2R levels were found between the limited and diffuse cutaneous subsets. However, PIIINP concentrations were significantly higher in anti-Scl-70 positive SSc patients compared with those of anti-Scl-70 negative patients (p = 0.01). Serum PIIINP levels were significantly higher in SSc patients with restrictive pulmonary function (FVC < 80%) than in patients with normal pulmonary function (p < 0.05). The correlation between PIIINP levels and FVC (p < 0.05) was negative, but the correlation between PIIINP levels and modified Rodnan skin scores (p < 0.05) was positive. sIL-2R levels were not correlated with skin and pulmonary involvement of SSc. There was no difference in vWF levels between those of the SSc patients and those of the control groups.
Conclusion: These results suggest that serum PIIINP serves as a biologic marker for the extent of skin and pulmonary involvement in systemic sclerosis. Increased serum levels of sIL-2R in SSc patients support a role for T lymphocyte activation in the pathogenesis of systemic sclerosis.