MPO and juvenile idiopathic arthritis: To quantify NET formation in the peripheral blood of JIA patients, plasma levels of cf-DNA and MPO-DNA complexes, as major components of NETs, were measured, there was a marked increase in levels of cf-DNA and MPO-DNA complexes in peripheral blood of JIA patients when compared to HCs [691.4 ± 15.37 ng/mL vs. 611.2 ± 21.53 ng/mL, p = 0.0043; 0.1430 (IQR:0.0952-0.2210) vs. 0.0797 (IQR: 0.05125-0.1500), p = 0.0030; Figure 2A].