Lymphocyte labelling with indium: cytotoxicity studies.

Viability studies on lymphocytes labelled with indium In111 using oxine as a ligand showed impairment as measured by trypan-blue assessment and rosetting ability. In addition, lymphocyte response to phytohaemagglutinin stimulation as measured by tritiated-thymidine uptake was also impaired at levels where adequate cell labelling had taken place. Cadmium toxicity was not noticed, and the use of tropolone as a ligand offered possibilities of reduced cellular toxicity. Such cytotoxicity may not have been important in earlier reported studies on granulocytes where the large numbers available for in vivo work and the short periods of study still allowed useful conclusions to be drawn. However, because of the prolonged lifespan of the human lymphocyte, the cytotoxic effects of the processing might well make the long-term studies which would be of interest much less reliable for clinical assessment.