PRTN3 and granulomatosis with polyangiitis: While neutrophil infiltration and microabscess formation dominate the early phase of the granulomatous inflammation in GPA or PR3-AAV, over time, the neutrophil-rich necrotizing lesions are converted into a monocyte/macrophage-rich granuloma, and this is accompanied by infiltration of lymphocytes such as T cells [16,17].