In this study, we examined whether PR3-ANCA serum and purified IgG from WG patients were truly capable of activating human peripheral blood mononuclear cells (PBMCs) similary to the combination of murine anti-human PR3 Abs and THP-1 cells to release proinflammatory cytokines. This evidence concerns the gene PRTN3 and granulomatosis with polyangiitis.