In vitro labeling of platelets with stable rubidium compounds.

It is a common practice in diagnostic hematology to mark blood cells with radioactive tracers, such as 51Cr, 55Fe, 75Fe, etc., to determine their life-span and study their metabolism. A program has been started to verify the possibility of marking blood cells with stable indicators, assayed by radioisotope-induced X-ray fluorescence analysis. All elements may be considered as indicators aggregating to blood cells, and for in vivo measurements, which are not toxic in the quantities injected, calculated on the basis of the limit of detection of the technique. In this study platelets were marked with a very small quantity of stable compounds of rubidium, a potassium analog. Measurements were carried out in vitro on platelets of normal subjects and in vivo on platelets of rats and rabbits. Several survival curves were deduced and life-span values obtained in accord with previously reported values.