We investigated serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) and the activity of extracellular superoxide dismutase (EC-SOD) in rheumatoid arthritis (RA). We also considered whether there was a correlation between sICAM-1 and EC-SOD and disease activity.
Levels of sICAM-1 were measured in serum from 42 patients with active RA and 30 control subjects by enzyme-linked immunosorbent assay (ELISA). EC-SOD activity was determined in sera isolated from patients with active RA and from controls.
The serum levels of sICAM-1 were significantly higher in patients with RA than in control subjects (p<0.001). In contrast, the activity of EC-SOD was significantly lower in RA patients than in healthy controls (p<0.001). A significant negative correlation was found between the levels of sICAM-1 and EC-SOD activity (r=-0.39, p<0.01). There was a statistically positive correlation between sICAM-1 levels with Ritchie articular index (RAI) score and C-reactive protein (CRP) (r=0.32, p<0.05; r=0.44, p<0.01, respectively).
These results show that the increased levels of sICAM-1 present in active RA patients might be due to the decreased activity of EC-SOD, and increased levels of sICAM-1 may also reflect disease status or activity.