A POSITIVE CORRELATION BETWEEN T-CELL-RECEPTOR MUTANT FREQUENCIES ANDDICENTRIC CHROMOSOME FREQUENCIES IN LYMPHOCYTES FROM RADIOTHERAPY PATIENTS

Dose estimates for the assessment of future risks, following accidenta l exposure to radiation, for certain diseases such as cancer usually r ely on both physical and biological quantitative analyses. A tradition al biological method of choice is the measurement of chromosome aberra tion frequencies in peripheral-blood lymphocytes. However, thorough ex amination of large sample populations is time and labor intensive. Rec ently, it became possible to measure mutant frequencies in T lymphocyt es; one method is a colony assay at the HPRT gene, and the other is a flow-cytometric assay at the T-cell-receptor (TCR) gene. To test for t he possible use of these mutation assays, concurrent measurements were taken on blood samples from women who previously received a full cour se of radiation therapy for gynecological cancer. The results showed t hat the frequency of TCR mutants correlated reasonably well with that of dicentric chromosomes, whereas the frequency of HPRT mutants did no t. Possible uses of the TCR mutation assay in combination with the con ventional chromosome analysis or micronucleus assay after exposure of a relatively large population are discussed.