Labelling of human and rabbit platelets with 111Indium-oxine complex

Platelets suspended in buffer were labelled with 111Indium-xoine. In the isolation procedure the platelets and a fraction of the erythrocytes are processed simultaneously, whereby the erythrocytes serve as a supporting cushion in the centrifugation steps. Various factors which influence the labelling effectiveness were examined, and the method's utility was estimated by in vivo studies in rabbits. A platelet concentration of more than 800 x 10(9)/1 and an oxine concentration of approximately 6 micrograms/ml in a plasma-poor system (transfer of platelets from plasma to buffer without further washing steps) will yield a high labelling efficiency. If the platelet isolation yield is to be large, a slight erythrocyte-leucocyte contamination must be accepted. Our experimental results indicated that this is permissible. In vivo investigations of 5 rabbits showed in vivo recoveries of platelets from 61--74% and mean survival times from 69 h to 110 h. This supports the assessment that the method of platelet isolation and labelling is gentle.