PRTN3 and osteoarthritis: Both RA sera and SF induced a pronounced increase in NETosis, which was paralleled by an increase in the nucleosome content of the supernatant (Figure 4A,B), as well as in ROS production (Figure 4C) when compared with healthy serum or osteoarthritis SF, respectively.To assess whether antibodies participate in the effects of RA serum on normal PMNs, we depleted IgG from serum of ACPA-positive and -negative RA patients and healthy controls.