Role of Mac-1 and ICAM-1 in ischemia-reperfusion injury in a microcirculation model of BALB/C mice.

The leukocyte beta 2-integrin Mac-1 (CD11b/CD18) and its endothelial ligand intercellular adhesion molecule 1 (ICAM-1) are involved in leukocyte adhesion to and macromolecular leakage from postcapillary venules during inflammatory reactions. Both events are also encountered after ischemia-reperfusion of striated muscle, suggesting a central role of both adhesion proteins in reperfusion injury. Using intravital fluorescence microscopy and a microcirculation model in awake BALB/C mice, we investigated the effects of monoclonal antibodies (MAb) and Fab fragments to Mac-1 and MAb to ICAM-1 on leukocyte-endothelium interaction and macromolecular leakage of fluorescein isothiocyanate-dextran (1.5 x 10(5) mol wt) in striated skin muscle after 3 h of ischemia followed by reperfusion. We demonstrated that administration of MAb and Fab to Mac-1 before reperfusion was as effective as administration of MAb to ICAM-1, which was found to be significantly upregulated in the postischemic tissue by immunohistochemical analysis, in preventing postischemic leukocyte adhesion to and macromolecular leakage from postcapillary venules, whereas postischemic leukocyte rolling was not affected after MAb administration. Postischemic capillary perfusion was efficiently preserved in animals treated with anti-Mac-1 and anti-ICAM-1 MAb compared with animals receiving the isotype-matched control antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)