Leukocyte labeling with technetium-99m tin colloids.
Triple density gradients of metrizamide in plasma (MP) were used to characterize label distribution in human leukocyte preparations incubated with 99mTc tin colloids. Less than 50% of the cell-associated radioactivity was specifically bound to leukocytes when heparinized blood was rotated with stannous fluoride colloid ([Tc]SFC). Labeling efficiency in leukocyte rich plasma (LRP) averaged 44%, of which greater than 90% was specifically bound to leukocytes. MP-gradient analysis also revealed that leukocyte labeling did not occur with stannous chloride colloid, nor when citrate was present during rotation with [Tc]SFC. When citrate was added after labeling to "solubilize" unbound [Tc]SFC, radiocolloid was removed from the leukocytes, indicating that the mechanism of [Tc]SFC labeling is adherence rather than phagocytosis. Technetium-labeled neutrophils exhibited normal in vitro chemotaxis and no lung uptake in vivo. Technetium-labeled mononuclear leukocytes, on the other hand, exhibited prolonged lung transit in vivo. Neither [Tc]SFC cell preparation showed signs of in vivo reoxidation to pertechnetate.
D006801:Humans; D007553:Isotope Labeling / Q000379:methods*; D007962:Leukocytes; D013667:Technetium; D017556:Technetium Compounds; D014001:Tin; D017971:Tin Compounds
D017556:Technetium Compounds; D017971:Tin Compounds; C033493:technetium Tc 99m tin colloid; D013667:Technetium; D014001:Tin