DNA HISTOGRAM ANALYSIS OF HUMAN HEMATOPOIETIC CELLS

Abstract

The proliferative activity of human neoplasms [particularly leukemia] may be an important determinant for therapeutic management. The advent of automated flow-through systems measuring cellular DNA content through fluorescence has considerably facilitated the analysis of cellular kinetics. Using a pulse cytophotometer ICP-11 (Phywe Co., Goettingen, Germany), 3 different fluorescent staining techniques for DNA histogram measurement on human hemopoietic cells were tested: mithramycin, ethidium bromide and a combination of ethidium bromide and mithramycin. Employing the tritiated thymidine labeling index as reference standard for comparison with the DNA histogram-derived S-phase fractions, linear correlations were obtained using ethidium bromide alone and ethidium bromide in combination with mithramycin as staining techniques. The fluorescence intensity was increased 4 fold to 5 fold by the use of the 2-dye combination, resulting in a substantial decrease in the coefficient of variation of DNA histograms to 1.5%-2%. This augmented histogram resolution is an important condition for detecting small-degree numeric chromosomal aberrations and discrete drug perturbation effects.