Differences between human lymphocyte subpopulations with respect to the uptake and incorporation of [3H]uridine and ribonucleoside triphosphate pools.

Cellular [³H]uridine uptake and incorporation into RNA were compared in human tonsil lymphocyte subpopulations obtained by separation on nylon-wool column. While the nonadherent subpopulation, Fraction I, contained 74.5 ± 8% E-rosette forming T-lymphocytes, the adherent fraction, Fraction II, contained 6.5 ± 3.5% of the same cells.The B-cell-enriched Fraction II of lymphocytes, freshly prepared from tonsils, was 2.5-3 times as active as Fraction I with respect to both uptake and incorporation of [³H]uridine. However, in phytohaemagglutinin-stimulated cultures the T-cell-enriched Fraction I proved to be more active with regard to ³H-uridine incorporation.The size of the four ribonucleoside triphosphate pools determined by the RNA-polymerase test was practically the same in both lymphocyte subpopulations. The radioactivity of the acid soluble cell fraction after [³H]uridine labeling consisted of about 60% [³H]UTP in both B- and T-cell-rich lymphocyte fractions, as determined by chromatography on PEI cellulose.On the basis of these results it seems unlikely that [³H] uridine labeling is a specific marker of either of the lymphocyte subpopulations.