Modification of the BrdU/H33258 technique for flow cytometry based on the pH-dependence of the fluorescence of H33258 stained DNA.

A simple analytical method is described for the evaluation of cell cycle progression data by modification of the BrdU/H33258 technique for flow cytometry. This procedure allows to obtain quenched and unquenched DNA-histograms of cells containing BrdU-substituted DNA by staining with one dye only, namely H33258. Quenched histograms are obtained at pH = 7 and give information about how far cells have passed the cell cycle since the beginning of the incubation. The unquenched ones obtained at pH less than or equal to 4 of the staining solution give information about the actual position of the cells in the cell cycle.