Endothelial selectins are expressed and functional in the BM microvasculature after irradiation. Fluorescently labeled PMNs obtained from mouse BM were injected into C57BL/6 mice before (nonirradiated, left panels) or 3 hours after lethal irradiation (irradiated, right panels). Mice had been treated with control rat IgG (Ctrl), anti–P-selectin (P-sel), anti–E-selectin (E-sel), or both antiselectin antibodies (P&E-sel). (A) The fractions of cells interacting with the BM microvasculature, (B) rolling velocities, and (C) the fractions of cells arrested on the BM microvasculature were determined by analysis of video recordings from fluorescence intravital microscopy experiments. The number of mice per group is indicated. *P < .05; **P < .01; #P < .001.