Labeling Human Lymphocytes with Mercury-197

A simple method for labeling human lymphocytes with Hg-197 is de scribed. Lymphocytes were isolated from hunuin blood and purified by the Ficoll—Hypaque method. Labeling was carried out by incubating viable cells suspended in saline with Hg.197 for different time intervals and at dif ferent temperatures. The labeling yield varied from 48% for 1 million cells to about 70% for 10 million celLs after incubation with 2 1uCi of Hg 197 for 2 hr at 37°C. The temperature and incubation period beyond 1 hr had no appreciable eflect on the labeling yield. The yield increased by a factor of 1.5 when the cells were stimulated by phytohemagglutinin. Sub cellular distribution studies showed that 60% of the tracer lOcalized in the nucleus and cell membrane, while the remaining portion concentrated in the mitochondrial and microsomal fractions.