Anti-MPO recognizes MPO and induces glomerular leukocyte adhesion in LPS-pretreated mice. (A) Serum from MPO^−/− mice immunized with MPO peptide was assessed via ELISA for its ability to recognize recombinant murine MPO. Serum from a nonimmunized mouse is shown as comparison. OD₄₅₀ data are shown as mean ± SEM of samples from n = 6 immunized mice, diluted 1:100 and measured in duplicate. (B) Glomerular leukocyte adhesion was assessed via intravital microscopy in LPS (0.1 μg, 4 hours)–pretreated mice that received either anti-MPO or anti-OVA. Following a basal reading of adhesion 4 hours after LPS, mice received either anti-MPO (50 μg, intravenously, n = 14) or anti-OVA (50 μg, intravenously, n = 8), and adhesion was reassessed 15, 30, and 60 minutes later. (*P < .001 vs anti-OVA via 2-way ANOVA.) (C-D) Representative intravital microscopy images of glomeruli before (C) and 60 minutes after (D) administration of anti-MPO. Arrowheads denote adherent leukocytes stained via rhodamine 6G. Images were acquired with a Zeiss Axioplan 2 Imaging microscope equipped with a 20×/WI 0.5 NA objective lens.