Use of a cell sorter for assays of cell clonogenicity.

A fluorescence-activated cell sorter has the capability of recognizing, categorizing, counting, and sorting cells, and it thus provides a convenient and rapid method for "micromanipulation" of known numbers of cells into appropriate vessels for cell viability or clonogenicity studies. Subsequent microscopic observation of the sorted cells allows discrimination between the separate processes of cell attachment (plating efficiency) and clonogenic growth (viability). Examples are presented showing the power of these techniques for studying the low-dose regions of radiation survival curves for Chinese hamster V79 cells grown as monolayers or spheroids, for cells irradiated under aerobic versus hypoxic conditions, and for cells of large spheroids exposed to Adriamycin, where the slow penetration of the drug results in a differential exposure to the various cell subpopulations.