PRTN3 and granulomatosis with polyangiitis: The percentage of monocyte cell surface PR3 expression was increased in patients with GPA (median 5.78%, IQR 4.74–6.68) compared with HC (3.47%, IQR 3.15–3.47) and patients with MPA (3.44%, IQR 3.31–4.13) (both p<0.01, one-way ANOVA) (figure 5B).