The deoxyribonucleoside 5′-triphosphate (dATP and dTTP) pool in phytohemagglutinin-stimulated and non-stimulated human lymphocytes

The pool size of dATP and dTTP in human lymphocytes was studied in untreated and PHA-treated cells. Different methods of extracting the cellular content of dATP and dTTP have been investigated and extraction with 60% methanol was preferred. The pool size of dATP and dTTP in non-stimulated lymphocytes was about 0.2 and 0.05 pmoles/10⁶ cells, respectively. After treatment with PHA for about 50 h the dATP and dTTP pools reached peak values representing increases in the pools of 20 and 170 fold, respectively. The variation in the pool sizes during transformation was paralleled by the variation of the rate of incorporation of labeled deoxy-thymidine into cellular DNA.