Serum thrombomodulin - a reliable marker of disease activity in systemic lupus erythematosus (SLE): advantage over established serological parametersto indicate disease activity

To date no specific serological parameter is available to assess disease ac tivity in SLE. Soluble serum thrombomodulin is a new marker of endothelial cell injury and vasculitis. The objective of this study was to compare in v ivo soluble thrombomodulin as marker of disease activity in SLE with establ ished and recent serological parameters. One hundred and twenty-four sera o f 30 patients with proven SLE with different disease activities were tested for serum levels of thrombomodulin, intercellular adhesion molecule-1 (ICA M-1), E-selectin, vascular cell adhesion molecule-1 (VCAM-1), IL-2R, IL-6, IL-10, dsDNA by ELISA and dsDNA additionally by radioimmunoassay (RIA). C-r eactive protein (CRP), complement component C3, IgG, creatinine, anti-nucle ar antibodies (ANA) and intermediate filament antibodies were measured by s tandard laboratory tests. The clinical disease activity was evaluated by th e Systemic Lupus Activity Measure (SLAM). Correlations of the different ser ological SLE disease activity parameters with the SLAM scores revealed the highest significance for serum thrombomodulin (correlation coefficient 0.82 ). This was further confirmed by the intra-individual analysis of follow-up sera. In addition, a moderate correlation could be found for IL-6, IL-10, ICAM-1, CRP and erythrocyte sedimentation rate (ESR). In summary, soluble t hrombomodulin is the most important serological parameter of disease activi ty in SLE currently available, as shown by the in vivo studies. Soluble thr ombomodulin might be a valuable serological parameter for therapeutical con siderations.