Fig. 4

DNase-I complex activity does not differ in patients with systemic lupus erythematosus (SLE) compared to healthy controls. Normal human serum (N HS), heat-inactivated NHS (Hi-NHS) from SLE patients (n = 66) or sera from controls (ctrl) (n = 62) were separated on native DNA zymograms. Nuclease activity was detected as lack of ethidium bromide (EtBr) staining to DNA (dark bands). Heating efficiently inhibited all nuclease activity. a Representative zymogram for sera from two controls and two SLE patients with NHS as internal control and NHS + DNase-I to indicate free and bound DNase-I. b DNase-I complex activity was quantified and compared between SLE patients and controls. c-e Activity of the same band is shown for particular patient groups with low neutrophil extracellular trap (NET) degradation (c), low primary necrotic chromatin degradation (d) or low secondary necrotic chromatin degradation (e). Significance of difference was calculated using the Mann-Whitney test (b-e); n.s. not significant. Prim-Nec primary necrotic chromatin, Sec-Nec secondary necrotic chromatin, std. standard