Antibodies against CD99 and CD99L2 inhibit neutrophil extravasation in the cytokine-inflamed cremaster of WT and PECAM-1–deficient mice. Leukocyte rolling, adhesion, and extravasation in (A) 4-hour IL-1β or (B) 2-hour TNF-α inflamed cremaster were analyzed by intravital microscopy in WT (A-B) and PECAM-1–deficient mice (only panel A) intravenously injected with 50 μg antibody of preimmune co-IgG, affinity-purified anti-CD99 IgG (anti-CD99), or affinity-purified anti-CD99L2 IgG (anti-CD99L2; as indicated) or a combination of both antibodies (only panel B). Four or 2 hours later, respectively, the cremaster muscle was surgically prepared, and the number of rolling leukocytes (per second per millimeter), adherent leukocytes (per 10⁴ μm² of venule surface area), and extravasated leukocytes from cremasteric venules (per 10⁴ μm² tissue area) were determined by intravital near-infrared reflected light oblique transillumination microscopy. ***P < .001. **P < .01. *P < .05. Statistical analysis was done by ANOVA evaluating all available data (n = 3-6). Hemodynamic parameters are given in Tables 1 and 2.