Labeling human lymphocytes with mercury-197.

A simple method for labeling human lymphocytes with Hg-197 is described. Lymphocytes were isolated from human 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 different temperatures. The labeling yield varied from 48% for 1 million cells to about 70% for 10 million cells after incubation with 2 muCi of Hg-197 for 2 hr at 37 degrees C. The temperature and incubation period beyond 1 hr had no appreciable effect on the labeling yield. The yield increased by a factor of 1.5 when the cells were stimulated by phytohemagglutinin. Subcellular 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.