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99mTc-SnF2 colloid "LLK": particle size, morphology and leucocyte labelling behaviour.
C M McClelland1, E Onuegbulem, N J Carter
1Department of Biosciences, University of Kent, Canterbury CT1 3NG, UK.
Nuclear Medicine Communications
|January 28, 2003
Summary
Technetium-99m tin fluoride (99mTc-SnF2) is an effective leucocyte labelling agent, though its cell selectivity varies. Optimized conditions enhance labelling efficiency, but significant radiolabel efflux occurs post-labelling.
Area of Science:
- Nuclear Medicine
- Radiopharmacology
- Cell Biology
Background:
- Leucocyte labelling is crucial for infection imaging.
- 99mTc-SnF2 colloid exploits phagocytosis for labelling whole blood.
- Optimization of 99mTc-SnF2 leucocyte labelling is needed.
Purpose of the Study:
- To optimize leucocyte labelling with 99mTc-SnF2 in leucocyte-enriched plasma.
- To evaluate factors affecting labelling efficiency, cell selectivity, and radiolabel efflux.
- To characterize the physical properties of the 99mTc-SnF2 colloid.
Main Methods:
- Density gradient centrifugation for efficiency, selectivity, and efflux studies.
- Trypan blue assay for cell viability assessment.
- Laser scattering, electron microscopy, and membrane filtration for colloid characterization.
Main Results:
- 99mTc-SnF2 particles are aggregates with variable size distribution.
- Labelling efficiency is enhanced at 37°C and with centrifugation.
- Cell selectivity varies significantly between batches and blood samples.
- Viability of labelled cells is excellent, comparable to 99mTc-HMPAO.
- Significant radiolabel efflux (similar to 99mTc-HMPAO) observed over 4 hours.
Conclusions:
- 99mTc-SnF2 is a convenient and efficient leucocyte labelling agent.
- Variable cell selectivity may relate to colloid particle size variability.
- Significant radiolabel efflux necessitates consideration in clinical applications.