The accumulation of gallium-67-labeled leukocytes in rat cardiac allografts

One to eight days following transplantation, host peripheral blood leukocytes were labeled in vitro with 67Ga and injected into rats with heterotopic cardiac isografts and allografts. The labeled cells accumulated progressively in the rejecting allografts with peak accumulation occurring at the height of histologically definable rejection activity. There was a minimal accumulation of labeled cells in the isograft immediately postoperatively which correlates with the histologically identifiable mild inflammatory response secondary to operative ischemia. Radioactively labeled host leukocytes thus may serve as useful tracers for the in vivo demonstration and quantitation of the cellular events associated with the rejection reaction.