Granulocyte accumulation in ischemic/reperfused myocardium: Assessment with a technetium-99m-labeled antigranulocyte monoclonal antibody in the dog

This study tested the usefulness of technetium-99m-labeled antigranulocyte monoclonal antibody BW250/183 (AGMAb) for identifying granulocyte accumulat ion in ischemic/reperfused canine myocardium. In dogs with 90 minutes coron ary artery occlusion and 180 minutes reperfusion (n = 8), ischemic/reperfus ed myocardial samples demonstrated 8.5 +/- 2.4 times more Tc-99m-AGMAb accu mulation than nonischemic samples, Dogs given Tc-99m-labeled nonspecific hu man immunoglobulin instead of Tc-99m-AGMAb (n = 3) had about half as much a ccumulation (4.5 +/- 1.6, P < .05). Ex vivo myocardial imaging of Tc-99m-AG MAb demonstrated marked uptake in infarcted regions identified by absent tr iphenyl tetrazolium chloride staining. The amount of uptake was inversely r elated to the severity of ischemia (determined by radioactive microspheres) and directly correlated with tissue myeloperoxidase activity, a specific m arker of granulocyte accumulation. No increase in Tc-99m-AGMAb uptake occur red in dogs with 90 minutes ischemia! and no reperfusion (n = 3) or 15 minu tes ischemia and 180 minutes reperfusion (n = 2), In conclusion, Tc-99m-AGM Ab is taken up in reperfused infarcted myocardium by both nonspecific and s pecific mechanisms. Because the amount of uptake reflects myocardial granul ocyte accumulation, Tc-99m-AGMAb combined with nuclear imaging techniques m ay be useful for studying inflammatory processes in the heart in experiment al animal models and human beings.