Mice Deficient in Mac-1 (CD11b/CD18) Are Less Susceptible to Cerebral Ischemia/Reperfusion Injury

Abstract

Background and Purpose—Macrophage-1 antigen (Mac-1) (CD11b/CD18), a leukocyte β2 integrin, facilitates neutrophil adhesion, transendothelial migration, phagocytosis, and respiratory burst, all of which may mediate reperfusion-induced injury to ischemic brain tissue in conditions such as stroke. To determine the role of Mac-1 during ischemia and reperfusion in the brain, we analyzed the effect of transient focal cerebral ischemia in mice genetically engineered with a specific deficiency in Mac-1.Methods—Transient focal ischemia/reperfusion was induced by occluding the left middle cerebral artery for 3 hours followed by a 21-hour reperfusion period in Mac-1–deficient (n=12) and wild-type (n=11) mice. Regional cerebral blood flow was determined with a laser-Doppler flowmeter. Brain sections were stained with 2% 2,3,5-triphenyltetrazolium chloride to determine the infarct volume. Neutrophil accumulation was determined by staining the brain sections with dichloroacetate esterase to identify neutrophils.Results—Compared with the wild-type cohort, Mac-1–deficient mice had a 26% reduction in infarction volume (PConclusions—Mac-1 deficiency reduces neutrophil infiltration and cerebral cell death after transient focal cerebral ischemia. This finding may be related to a reduction in neutrophil extravasation in Mac-1–deficient mice.