The relationship between soluble interleukin 2 receptor levels and antidouble stranded DNA antibody levels in patients with systemic lupus erythematosus.

Levels of soluble interleukin 2 receptors (IL-2R) have been found to be elevated in the serum of patients with systemic lupus erythematosus (SLE) and are considered an indication of immune system activation in this disease. To assess the relationship between soluble IL-2R levels and other serological markers, we compared levels of soluble IL-2R and anti-double stranded DNA (anti-dsDNA) antibodies in SLE sera. In a cross sectional study of 34 patients with SLE, soluble IL-2R levels were elevated compared with healthy individuals (1126 U/ml vs 235 U/ml, p less than 0.0001), and a significant correlation between levels of soluble IL-2R and anti-dsDNA antibodies was present (r = 0.543, p = 0.0009). In a longitudinal study of 10 additional patients, the time courses of soluble IL-2R levels and anti-dsDNA antibody measurements were similar in 3 patients. In 7 patients, substantial differences in the levels of soluble IL-2R and anti-dsDNA antibodies over time were observed, including marked changes in anti-dsDNA antibody levels that were accompanied by only minor changes in soluble IL-2R levels, and soluble IL-2R measurements that were persistently elevated despite generally low anti-dsDNA antibody levels. Our results indicate that soluble IL-2R levels may not always parallel other serological markers of SLE, suggesting measurement of different facets of immune system activation by various assays.