STUDIES OF THE KINETICS OF INDIUM-111-LABELED GRANULOCYTES

Abstract

Studies of in vivo kinetics of granulocytes labeled in vitro with 111In were carried out in 10 normal subjects. The granulocyte suspension was prepared with a Ficoll-Hypaque density gradient and labeled with 111In oxine. No elution or reutilization of the radioisotope was demonstrable in vitro. The average intravascular recovery of In-labeled granulocytes was 30% .+-. 6, and the t 1/2 [half-life] was 5.0 .+-. 1.6 h. Normal in vitro function of these cells was demonstrated by bacterial killing and chemotaxis assays. Because 111In decays by .gamma. emission, the fate of in vivo labeled granulocytes can be followed with scintigraphic techniques. Images obtained indicated normal uptake of activity in the liver and spleen. Effective in vivo function of In-labeled granulocytes was demonstrated in 4 patients by the localization of radioactivity at sites of inflammation or abscess. Although the intravascular recovery is lower than that reported for some other radioisotope methods, the comparison of abnormal findings with normal values by this technique is probably valid. In-labeled granulocytes should prove useful in the study of granulocyte collection, transfusion, histocompatibility and storage.