Circulating intercellular adhesion molecule 1 in rheumatoid arthritis--relationship to systemic vasculitis and microvascular injury in nailfold capillary microscopy.

Intercellular adhesion molecule-1 (ICAM-1) is a membrane bound molecule that plays an important role in the pathogenic inflammatory responses observed in vasculitis. The aim of this study was to determine whether levels of soluble ICAM-1 sICAM-1) shedding into the circulation reflect the vascular injury found in nailfold capillaroscopy as well as systemic vasculitis in RA patients. We determined serum levels of sICAM-1 and soluble interleukin-2 receptor (sIL-2R) by an enzyme-linked immunosorbent assay in 79 RA patients. Serum levels of sICAM-1 were significantly increased in RA patients compared to 30 healthy controls. RA patients with clinical signs of systemic vasculitis showed significantly higher levels of sICAM-1 than those without vascular involvement. Although no significant correlation between sICAM-1 levels and the capillaroscopy findings were found, 75% of the patients with severe vascular changes in capillaroscopy exceeded normal sICAM-1 cut off value. Serum sICAM-1 concentrations correlated significantly with the erythrocyte sedimentation rate and serum sIL-2R, but not with the duration of RA, radiological stages, Ritchie index, age or type of treatment. These findings suggest that increased levels of sICAM-1 in serum of RA patients reflect systemic vascular involvement rather than a local vascular injury.