Comparison of the frequency of T-cell receptor mutants and thioguanine resistance induced by X-rays and ethylnitrosourea in cultured human blood T-lymphocytes.
We have investigated two assays for measuring the induction of mutations using human T-lymphocytes isolated from leukocyte residue buffy coats obtained from normal donors. Variant cell frequency of T-cells defective in the T-cell receptor (TCR) gene expression was measured using a 2-color flow cytometry, and 6-thioguanine-resistant (TGr) cells were determined using a cloning technique at the HPRT gene after treatment with 250 kVp X-rays or ethylnitrosourea (ENU). The frequencies of TCR mutant cells as well as those of TGr cells increased with increasing doses of X-rays or concentrations of ENU studied. For TCR mutants, the induced mutation frequencies at D37 (giving 37% survival) were 31.7 x 10(-4) and 11.0 x 10(-4) for X-rays and ENU, respectively. For TGr T-cells, the induced mutation frequencies at D37 for the same mutagens were 14.4 x 10(-6) and 75.5 x 10(-6), respectively. Over the dose range studied the relationship appears to be linear between the mutation induction of TCR and that of TGr for X-rays or ENU. However, X-rays may induce more TCR mutants against less induction TGr T-cells, and ENU may cause a reverse result. The sensitivity of the assay of each biological endpoint in human blood T-lymphocytes may be different.
Mei
N
N
Department of Radiation Biology and Health, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Kunugita
N
N
Nomoto
S
S
Norimura
T
T
D000328:Adult; D000477:Alkylating Agents / Q000494:pharmacology; D005038:Ethylnitrosourea / Q000494:pharmacology*; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D007158:Immunologic Techniques; D008297:Male; D008875:Middle Aged; D009152:Mutagenicity Tests / Q000592:standards*; D009153:Mutagens / Q000494:pharmacology; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000528:radiation effects*; D013866:Thioguanine / Q000494:pharmacology; D014965:X-Rays
D000477:Alkylating Agents; D009153:Mutagens; D011948:Receptors, Antigen, T-Cell; D007041:Hypoxanthine Phosphoribosyltransferase; D013866:Thioguanine; D005038:Ethylnitrosourea