Proteinase 3 expression on neutrophil membranes from patients with infectious disease

Proteinase-3 (PR3) is an abundant serine proteinase stored in the azurophilic granules of neutrophils and released to the cell surface upon activation where it contributes to local tissue destruction and inflammation. The subpopulation of membrane PR3 (mPR3) high expression (PR3-high) varies among individuals. There are many reports about PR3 in Wegener's granulomatosis, but few about PR3 expression in patients with common inflammatory disorders, such as sepsis. The mPR3 expression on neutrophils from 56 patients with inflammatory disorders and from 64 healthy volunteers was examined by flow cytometry. High variability in the percentage of PR3-high (%PR3-high) neutrophils was observed in healthy volunteers and patients with inflammatory disease, and the %PR3-high was significantly greater in the patients (72 +/- 19% vs 55 +/- 20%, P < 0.0001). Overall neutrophil PR3 expression in patients with infectious diseases, especially systemic inflammatory response syndrome (SIRS) was significantly high (P < 0.01) and showed a positive correlation with C-reactive protein (CRP). Even under inflammatory conditions not involving autoimmune vasculitis, there are significant increases in both the absolute surface expression of PR3 and the numbers of neutrophils expressing high levels of PR3 and these correlate with CRP levels. The data are consistent with a model in which neutrophil membrane expression of PR3 is greatly influenced by an in vivo inflammatory environment.