Measurement of mutagenesis in mammalian cells.

A method using mammalian cells in vitro for detection and quantitation of mutagenic actions that appears to be useful for screening for carcinogenesis and genetic damage by environmental agents is presented. The method involves use of stable human--Chinese hamster ovary hybrid cells that have retained a single human chromosome not necessary for cell reproduction. Forward mutations are detected in genes necessary for production of specific human cell surface antigens. Such mutants form colonies in the presence of specific antisera and complement that destroy the unmutagenized cells. Use of the method is illustrated for the action of x-irradiation, N-methyl-N'-nitro-N-nitrosoguanidine, and caffeine. The method appears to be unique in that it permits assessment of lesions that cause loss of all or most of the chromosome as well as various localized gene mutations. The former action is particularly important because of the major involvement of chromosomal lesions in an extremely important class of human genetic disease.