IL-1β– and TNF-α–induced leukocyte responses in mouse cremasteric venules of WT controls and ICAM-2–deficient mice as observed by intravital microscopy. (A) The expression profiles of ICAM-2 and PECAM-1 in representative cremasteric venules of WT mice. Unstimulated cremaster muscles were immunostained and observed for the expressions of ICAM-2 and PECAM-1, as detailed in “Materials and methods.” The figure also shows merged images captured from the 2 channels used. Each image is representative of that obtained from 3 to 5 vessels per tissue (n = 3 mice per group). Bar = 20 μm. (B-C) Mice (WT controls or ICAM-2 KO mice) treated with intrascrotal saline (400 μL per cavity, open bars), IL-1β (50 ng per mouse, closed bars), or TNF-α (300 ng per mouse, closed bars); 4 hours later, leukocyte responses were quantified as detailed in “Materials and methods.” The data represent mean ± SEM of 3 to 7 animals. *P < .05 and **P < .01 versus saline-treated levels. In addition, significant differences between the 2 strains of mice are indicated by lines.