Increased levels of intercellular adhesion molecule-1 in the serum of patients with systemic lupus erythematosus.

Intercellular adhesion molecule-1 (ICAM-1) is a membrane-bound molecule that is primarily involved in cell-cell adhesive interactions of the immune system. The levels of soluble ICAM-1 (s-ICAM-1) shed into the circulation were studied in the sera of patients with systemic lupus erythematosus (SLE) by an enzyme linked immunosorbent assay. Serum concentrations of s-ICAM-1 were significantly increased in 61 patients with SLE compared to 51 controls (mean +/- SEM: 564 +/- 30 versus 348 +/- 17 ng/ml, p < 0.0001) and 41% of patients had higher serum levels than the normal cut off value of 584 ng/ml. Among the various clinical manifestations, skin involvement was significantly associated with high serum levels of s-ICAM-1. Individual values of serum s-ICAM-1 concentrations in patients with SLE correlated significantly with two different disease activity indices, as well as with the erythrocyte sedimentation rate and serum levels of soluble interleukin-2 receptors, but not with serum levels of anti-dsDNA antibodies or C4. No significant differences in s-ICAM-1 levels were found between patients receiving immunomodulatory treatment and those who were not. These findings suggest that s-ICAM-1 measurement may serve as an additional serologic marker of disease activity in patients with SLE. Further studies to determine whether increased s-ICAM-1 shedding has any pathogenetic significance or biological role in SLE are warranted.