Monoclonal leukocyte antibody does not decrease the injury of transient focal cerebral ischemia in cats

Background and Purpose: We tested the hypothesis that inhibition of leukocyte function by administration of monoclonal antibody 60.3 (MoAb 60.3) improves electrophysiological recovery and decreases injury volume following transient focal cerebral ischemia in cats. Methods: Halothane-anesthetized cats underwent 90 minutes of left middle cerebral artery and bilateral common carotid artery occlusion followed by 180 minutes of reperfusion. Cats were assigned to receive either 2 mg/kg MoAb 60.3 (n=8) directed at the CDw18 leukocyte antigen complex or an equal volume of diluent (sterile saline; n = 10) at 45 minutes of ischemia in a blinded fashion. Results: Blood flow to the left temporoparietal cortex decreased to <5 ml/min/100 g with ischemia, but was minimally affected on the right side. Postischemic hyperemia occurred in the left caudate nucleus, whereas blood flow in other brain regions returned to control. No region demonstrated delayed hypoperfusion, and there were no differences between groups. Somatosensory evoked potential recorded over the left cortex was ablated during ischemia and recovered to <10% of baseline amplitude at 180 minutes of reperfusion in both groups. Left hemispheric injury volume, as assessed by 2,3,5-triphenyltetrazolium chloride staining, was not affected by drug treatment (mean±SE values: MoAb 60.3, 37±5%; placebo, 38±7% of hemisphere). Conclusions: Inhibition of leukocyte function with MoAb 60.3 does not afford protection from severe focal ischemia and reperfusion in cats.