Objective: To determine serum interleukin-10 (IL-10) levels in systemic lupus erythematosus (SLE) patients and to assess their relationship with disease activity.
Methods: Forty-one SLE patients and 35 controls were studied. Paired serum samples were collected from all SLE patients at the time of their presentation with active disease and at 4 weeks after the institution of treatment. IL-10 levels were determined in the sera and were compared with disease activity, measured using the SLE Disease Activity Index (SLEDAI) and laboratory parameters such as the circulating immune complexes (CIC), C3, C4, anti-DNA antibody, IgG, IgM, and IgA.
Results: The IL-10 levels in SLE patients were significantly higher than those of controls (mean +/- SE, 29.2 +/- 6.8 vs. 3.5 +/- 0.6 pg/ml, p < 0.01). Elevated IL-10 levels correlated well with the SLEDAI in SLE patients (r = 0.46, p < 0.01), but did not correlate with other laboratory activity indices. The changes in serum IL-10 levels also correlated with the changes in the SLEDAI score during the patients' disease course (r = 0.51, p < 0.01).
Conclusion: Serum levels of IL-10 are elevated in SLE patients and increased IL-10 correlates well with SLE disease activity.