Characterization of endothelial adhesion molecules in scid/mdx mice. Adhesion molecule expression on the endothelium of dystrophic muscle was evaluated with the use of in vivo staining followed by observation with intravital microscopy and on cryosections before and after TNF-α stimulation or muscle exercise. Fluorescein-protein (F/P) ratios for mAbs were 3.0 for anti-E- and anti-P-selectin mAbs, 3.2 for anti-ICAM-1 mAb, 2.9 for anti-MAdCAM-1 mAb, and 3.4 for anti-VCAM-1 mAb. An anti-human Ras mAb was used as control and had an F/P ratio of 3.6 (data not shown). Murine vessels of scid/mdx mice expressed P-selectin in basal condition as shown by in vivo staining. Moreover, after muscle exercise and TNF-α stimulation, we registered significant improvement in the number of vessels expressing P-selectin and VCAM-1. In vivo staining data were confirmed by immunofluorescence staining showing the expression of P-selectin or VCAM-1 (in red) but not E-selectin, MadCAM-1, or ICAM-1 in CD31⁺ venules (shown in the middle line of each condition), αSMA-positive arterioles (shown in the lower line of each condition), or murine muscle vessels (both in green). DAPI-positive nuclei are shown in blue. Vessels were acquired at ×40 magnification. Scale bars represent 100 μm for intravital microscopy (black-and-white images) and 10 μm for immunostaining (color images).