Mutagenicity monitoring in humans by autoradiographic assay for mutant T lymphocytes.

Somatic cell mutation which occurs in vivo in humans can be determined by measurement of the frequency of the 6-thioguanine-resistant (TGr) T lymphocytes in samples of peripheral blood. This frequency can be determined by either a short-term autoradiographic methodology or a longer cell-cloning methodology. The advantage of the former is the relative simplicity of the assay, while the latter allows recovery of mutant clones for further characterization. This report presents results of a longitudinal study of cancer chemotherapy nurses and other health care personnel by use of the autoradiography assay. The use of this assay in human mutagenicity monitoring and the analysis of the TGr cell frequencies are discussed in terms of age effects and validation of 'elevated' frequencies by use of the clonal assay. This report then presents evidence that both assays yield similar TGr cell frequencies in two groups of 'normal adults'. The mean variant frequency (+/- S.D.) for 82 autoradiographic assays was 8.7 (+/- 6.1) X 10(-6), while the mean mutant frequency (+/- S.D.) for 115 clonal assays was 6.5 (+/- 4.8) X 10(-6). In addition, concurrent autoradiographic and clonal assays on 33 individuals yielded mean values (+/- S.D.) of 8.4 (+/- 8.5) X 10(-6) and 10.5 (+/- 6.3) X 10(-6), respectively.