Radiochemistry and biostability of autologous leucocytes labelled with 99mTc-stannous colloid in whole blood.

Autologous leucocytes were labelled in whole blood by phagocytic uptake of 99mTc-stannous colloid. This colloid has a mean particle size of 1.5 micron and labels leucocytes with 81% efficiency. Individual cell uptakes were: granulocytes 42%, monocytes 39%. Isotonic sodium citrate added after the labelling procedure did solubilise excess colloid but was not necessary for adequate removal of excess colloid. Labelled leucocytes were shown in vitro to be viable and maintain normal bactericidal and chemotactic capacity. Biodistribution, clearance rates and dosimetry are presented. These results indicate that autologous leucocytes can be efficiently labelled with 99mTc-stannous colloid with good residual cell function.