Dose-responsive purine and pyrimidine requirements for the rescue from apoptosis of folate-deficient erythroblasts.

Folate-deficient erythroblasts were cultured in FDM made with dialyzed FBS. At 0 hour of culture, folic acid or combinations of nucleosides were added to the medium as indicated at the bottom of the figure. Thymidine (dT) and deoxycytidine (dC) were added in equimolar amounts as shown (eg, 20 indicates that 20 μmol/L dT and 20 μmol/L dC were added). Viable cell numbers, apoptosis, and phase of the cell cycle were determined at 32 (■) and 44 (▪) hours of culture. Data are ± SEM of 3 separate experiments.