Background Soluble forms of adhesion molecules may be found in the circulation, and increased levels of selectins have been reported in some connective tissue diseases. It was suggested that the measurement of levels of circulating soluble selectins is useful as an indicator of inflammatory disease.

Objectives To determine serum levels of soluble (s) E-, L-, and P-selectin in patients with rheumatoid arthritis (RA) and systemic sclerosis (SSc), and to determine whether levels of these molecules correlate with measures of disease activity and pulmonary involvement.

Methods Serum levels of sE-, L-, and P-selectin were determined by sandwich ELISA in 34 patients with RA, 30 patients with SSc and 15 healthy subjects. The patients with RA were classified according to disease activity, functional status, Larsen score reflecting anatomical joint damage, and the presence of pulmonary involvement. The presence of pulmonary fibrosis and DLCO were determined in patients with SSc.

Results The mean soluble selectin levels are shown in Table 1. sE- and sL-selectin levels were significantly higher in patients with active RA compared to inactive patients (respectively p < 0.05 and p < 0.05). Although sP-selectin level was higher in active RA patients than those in inactive patients, the difference did not reach statistically significant (p = 0.06). Significant correlations were found between sL-selectin and CRP (p < 0.05), and white blood cell count (p < 0.01) and between sP-selectin and CRP (p < 0.01), and erythrocyte sedimentation rate (p < 0.01). There were no correlations between selectin levels and Larsen score. sE-selectin level was increased in RA patients with advanced functional impairment (56.0 ± 39.8 in stage III-IV vs. 32.7 ± 13.6 ng/ml in stage I-II, p < 0.05). The presence of pulmonary involvement in patients with RA was not correlated with soluble selectin levels. sE-selectin levels was significantly higher in SSc patients with pulmonary fibrosis compared to other SSc patients (p < 0.05). There was a significant correlation between sE-selectin level and DLCO (r = -0.536, p < 0.01).

Conclusion These results suggest that the measurement of levels of serum soluble selectins may provide a useful additional marker for disease activity in RA patients and for pulmonary involvement, especially sE-selectin, in SSc patients.