Figure 5.

NSP-dependent anti-MPO IgG–stimulated IL-1β generation. (A) Monocytes from WT, NE^−/−/PR3^−/−, or NE^−/−/CG^−/−mice were primed with TNFα for 30 minutes and subsequently stimulated with anti-MPO IgG (αMPO). Supernatants were collected after 4 hours and analyzed for IL-1β by ELISA. NE^−/−/PR3^−/− mice displayed a significant reduction in anti-MPO IgG–induced IL-1β generation. Four independent experiments using a total of 48 mice were performed. Each experiment used pooled bone marrow monocytes from 4 mice per genotype. *P<0.05. (B) Exogenous addition of human PR3 increases IL-1β generation in anti-MPO IgG–stimulated DPPI^−/− monocytes. Human NE or PR3 (2.5 μg/ml each) was added to bone marrow monocytes at the beginning of the assay, and cells were subsequently primed with TNFα for 30 minutes before stimulation with anti-MPO IgG for 4 hours. Supernatants were analyzed by ELISA for IL-1β. Three independent experiments using a total of 24 mice were performed. Each experiment used pooled bone marrow monocytes from four WT and four DPPI^−/− mice, respectively. *P<0.05.