Kinetics, Distribution and Sites of Destruction of 111Indium‐labelled Human Platelets

Abstract

The survival, tissue distribution and fate of 111In-oxine labeled autologous platelets in 6 normal humans were studied with serial blood sampling, scintillation camera and computer-assisted imaging, whole body profile scanning and rectilinear scanning. 111In-platelets recovery in the circulation was 72 .+-. 16% and survival was 216 .+-. 17 h. Platelet survival curves fitted a linear function best. Initially platelets pooled rapidly in the spleen as a single exponential function, and at 90 min 26% of the injected 111In was located in this organ. Early hepatic uptake was significant and at 90 min constituted 16% of total body 111In-activity. As labeled platelets disappeared from circulation there was a 3-fold increase of radioactivity in the liver to reach 39% of whole body activity at 216 h. Radioactivity also increased significantly in the spleen (33.3% at 216 h). There was significant residual radioactivity in the thoracic and lower abdominal regions at 216 h, suggesting that platelets are sequestered in the bone marrow. Radioactivity in the lower limbs almost disappeared with time (0.7% at 216 h), indicating that utilization of platelets in the peripheral vasculature is not marked in normal subjects.