FROM FLOW CYTOMETRIC BRDURD DATA TO CELL-POPULATION GROWTH AND DOUBLING TIME

We describe a direct way to use now cytometric data for measuring the growth curve of a cell population. The starting point is analysis of t he intrinsic informative content of the time course, after bromodeoxyu ridine (BrdUrd) labeling, of the percentages of cells detected within four windows of biparametric BrdUrd-DNA histograms. We did not introdu ce a particular cell cycle model or use the hypothesis of exponential growth. We obtained a simple formal proof of the existence of four ind ependent formulae connecting the now cytometric data and the relative growth curve of the cell population. The formulae were then challenged in a number of simulated kinetic scenarios, moving away from their ex pected limits of validity. The results suggest additional uses of the formulae and a way of estimating cell-cycle-phase durations. Consideri ng exponential growth in the presence of cell loss, the formulae were used to estimate the potential doubling time from a single flow cytome tric measure vs. other procedures that additionally require an estimat e of the duration of the phase S. The theoretical precision of the pro cedures may differ depending on how cell loss occurs. (C) 1997 Wiley-L iss, Inc.