C4A and systemic lupus erythematosus: In addition to the association with overall disease activity, a significant positive correlation was seen between IL-10 measured at the first visit and commonly used markers of inflammation in SLE, including erythrocyte sedimentation rate (ESR) (r = 0.2189, p < 0.01) and anti-dsDNA antibodies (r = 0.2175, p < 0.01), and corresponding significant negative correlations with C3 (r = −0.2360, p < 0.01) and C4 (r = −0.2023, p = 0.02) (not shown).