Flow Cytometric Analysis of Chromosome Damage After Irradiation: Relation to Chromosome Aberrations and Cell Survival

Summary

Reproductive death of cultured cells is commonly assessed by measurement of clono-genic capacity which requires a culture period equivalent to about ten cell doubling times. Chromosome structural changes can be observed microscopically in stained preparations of mitotic cells but this requires tedious counting For a rapid determination of cellular sensitivity which might provide predictions of responses of tumors to various treatments, a new technique would be valuable if the dependence of responses on dose and radiation quality would correlate well with other cellular responses.

Flow cytometry has provided a technique for the rapid determination of DNA content of individual chromosomes of mammalian cells and of changes induced by various treatments. This technique involves selection of mitotic cells, the preparation of monodisperse chromosome suspensions, measurement of DNA content histograms and the analysis of these histograms by a computer program. Using this method we have determined changes in the distributions of chromosome frequency versus DNA content as a function of X-ray dose. The results are compared with dose effect relations for chromosome structural changes assessed by conventional cytogenetic techniques and for impairment of cellular clonogenic capacity.