Proteinase 3 and CD177 are expressed on the plasma membrane of the same subset of neutrophils

Abstract

Proteinase 3 (PR3) is found in granules of all neutrophils but also on the plasma membrane of a subset of neutrophils (mPR3). CD177, another neutrophil protein, also displays a bimodal surface expression. In this study, we have investigated the coexpression of these two molecules, as well as the effect of cell activation on their surface expression. We can show that CD177 is expressed on the same subset of neutrophils as mPR3. Experiments show that the expression of mPR3 and CD177 on the plasma membrane is increased or decreased in parallel during cell stimulation or spontaneous apoptosis. Furthermore, we observed a rapid internalization and recirculation of mPR3 and plasma membrane CD177, where all mPR3 is replaced within 30 min. Our findings suggest that the PR3 found on the plasma membrane has its origin in the same intracellular storage as CD177, i.e., secondary granules and secretory vesicles and not primary granules. PR3- and CD177-expressing neutrophils constitute a subpopulation of neutrophils with an unknown role in the innate immune system, which may play an important role in diseases such as Wegener's granulomatosis and polycythemia vera.

Proteinase 3, the Autoantigen in Granulomatosis with Polyangiitis, Associates with Calreticulin on Apoptotic Neutrophils, Impairs Macrophage Phagocytosis, and Promotes Inflammation

“…However, it is noteworthy that the membrane protein CD177, reported to be a protein that can associate with PR3 at the neutrophil plasma membrane, was not upregulated on apoptosis and was not part of this complex in RBL cells. Nonetheless, it was confirmed in this study that exogenous purified PR3 can specifically bind to CD177 expressed on resting RBL/CD177 cells, whereas no PR3 binding was observed on wild type RBL cells (data not shown), thus confirming earlier results (23,24) showing that CD177 is a receptor for exogenous PR3.…”

“…In neutrophils, PR3 is expressed on the same neutrophil subset as CD177 (also called NB1) (23,24), a GPI-anchored glycoprotein. CD177 has been suggested to be a PR3 "receptor" involved in PR3 constitutive membrane expression in neutrophils, and we hypothesized that the lack of constitutive PR3 membrane expression of RBL/PR3 cells could be due to the absence of CD177 expression in these cells.…”

Mapping of Conformational Epitopes on Human Proteinase 3, the Autoantigen of Wegener’s Granulomatosis

“…Although the vast majority of PR3 is stored intracellularly in primary granules together with other proteases, small amounts of PR3 prestored in as yet poorly characterized small vesicles are rapidly mobilized during priming. This small fraction of PR3 is externalized together with NB1 (CD177), a glycolipid-anchored membrane protein (5,6), and is presented on the neutrophil surface as a complex with NB1 (7). Simultaneous interaction of cANCAs with membrane-bound PR3 and FcgR is believed to trigger full activation and premature degranulation of extravasating neutrophils around small vessels in patients with active disease (3).…”

Complement Receptor Mac-1 Is an Adaptor for NB1 (CD177)-mediated PR3-ANCA Neutrophil Activation

“…In vitro experiments indicate that mPR3 high neutrophils respond with increased PR3-ANCA-mediated superoxide generation and degranulation, whereas other stimuli triggered a similar response in both neutrophil subsets (16). Neutrophil antigen B1 (NB1, CD177) is exclusively expressed in and on mPR3 high neutrophils and functions as a presenting receptor for PR3 on the cell membrane on this neutrophil subset (17)(18)(19). In a recent report, the percentage of NB1-expressing neutrophils was higher in ANCA vasculitis patients, compared with healthy controls.…”