The Significance of IL-6 in Systemic Rheumatic Diseases: Systemic Lupus Erythematosus and Rheumatoid Arthritis

Systemic lupus erythematosus(SLE) and rheumatoid arthritis(RA) are the widely recognized rheumatic diseases of unknown etiology in which extensive immune dysfunction has been reported. Cytokines are considered to be the most important secretions of the immune system that participate in a variety of cellular, inflammatory and pathogenic processes in human disease. Since imbalance of the cytokine network in autoimmune disease may be detrimental for the severity or clinical manifestation of the disease, I determined serum level of IL-6 in patients with SLE, RA, and normal controls.

The results were as follows:

1) The serum levels of IL-6 in patients with SLE(p=0.0032) and RA(p=0.0001) were significantly higher than those of normal controls.

2) The serum levels of ESR, CRP, and complements did not correlated with serum IL-6 levels. Only the levels of anti-dsDNA in patients with SLE showed correlation with that of serum IL-6. And the serial follow-up of serum IL-6 levels in 6 systemic lupus erythematosus patients show no significant correlation.

3) There were no significant correlation between serum IL-6 of RA patients and disease activity markers such as CRP and rheumatoid factors.

This results indicate that serum IL-6 levels of SLE and RA patients were significantly higher than that of normal controls, and needs further study to be used as a marker for disease activity.