Clinical significance of soluble CD31 in patients with systemic sclerosis (SSc): Association with limited cutaneous SSc

Objective. To determine serum levels of soluble CD31 (sCD31) and its clinic al associations in patients with systemic sclerosis (SSc). Methods. Serum sCD31 levels from 70 patients with SSc were examined by ELIS A. For a longitudinal study, 64 sera from 17 SSc patients were analyzed (fo llowup: 0.4-3.9 yrs). Results. Serum sCD31 levels were elevated in patients with SSc (n = 70) com pared with healthy controls (n = 20) and patients with systemic lupus eryth ematosus (n = 15). Serum sCD31 levels were higher in patients with limited cutaneous SSc (ISSc; n = 37) than those with diffuse cutaneous SSc (n = 33) . Patients with elevated sCD31 levels had pulmonary fibrosis and decreased percentage vital capacity (%VC) less frequently than those with normal sCD3 1 levels. sCD31 levels correlated positively with %VC in patients with SSc. This association of elevated sCD31 levels with the lower frequency of pulm onary involvement and better %VC was still observed when analyzed among ISS c patients alone. The elevation of sCD31 was associated with shorter diseas e duration in patients with ISSc. In a longitudinal study, 75% of patients with SSc showed increased sCD31 levels only transiently in the early phase of the disease. Serum sCD31 levels remained normal during followup in all p atients with normal sCD31 levels at the first visit. Conclusion. Elevated sCD31 levels were associated with ISSc with relatively early onset and lower frequency and severity of pulmonary fibrosis. These results suggest that sCD31 would be a protective factor for the development of skin sclerosis and pulmonary fibrosis in SSc, since sCD31 has an anti i nflammatory effect by inhibiting CD31 mediated transendothelial migration o f leukocytes.