Correlation between DNA synthesis and intracellular NAD in cultured human leukemic lymphocytes

The NAD + level in lymphocytes obtained from an individual with acute monocytic leukemia increased five-fold and then remained constant when the cells were adapted to growth in suspension culture. When the NAD + level of established cells was lowered by means of a nicotinamide-poor medium or by the action of 1-methyl-1-nitrosourea, there was a concomitant decrease in the rate of DNA synthesis. These results indicate that there is a direct correlation between intracellular NAD + and the synthesis of DNA in cultured leukemic lymphocytes. However, the exact nature of the relationship remains speculative.