Objectives We aimed to measure serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) and erythrocyte membrane sialic acid (SA) activity and the correlation of these parameters in patients with rheumatoid arthritis (RA), and to investigate the correlation of these parameters with the disease activity.

Methods Serum sICAM-1 levels were determined with sandwich enzime-linked immunosorbent assay (ELISA) and SA concentration was determined according to the method of Shamberger in sera from 42 patients with RA and in 30 healthy controls. Erythtrocyte sedimentation rate (ESR) was determined according to the Westhergen method and C-reactive protein (CRP) by nephelometric method. Disease activity was assessed by disease activity criterias.

Results Significantly lower erythrocyte membrane SA and higher serum levels of sICAM-1 were found in patients with RA than in healthy controls (p < 0.001 for both). Significant negative correlation between sICAM-1 level and erythyrocyte membrane SA concentration (r = ?0.49, p < 0.001), and positive correlation between sICAM level with Ritche articular index (RAI) score and CRP (r = 0.32, p < 0.05; r = 0.44, p < 0.01, respectively), were observed. No significant correlation was found between sICAM-1 level with ESR, age and disease duration. There was not any correlation between values of CRP, RAI score and ESR with erythrocyte membrane SA concentration.

Conclusion From these data, it is concluded that decreases in erythrocyte membrane SA concentration and increases in sICAM-1, ESR and CRP levels are present in RA, and that the decrease in erythrocyte membrane SA concentration in RA might be due to increased sICAM-1, and increased levels of sICAM-1 and correlations with other parameters may be a significant and novel marker for evaluating the disease status and the activity of RA.