A sensitive assay for 6-thioguanine-resistant lymphocytes.
We have defined variants (V) resistant to 6-thioguanine (TG) by their ability to divide at least once during a 72-h incubation in a medium containing 0.2 mM TG. We blocked cytokinesis by adding cytochalasin B (CB) after 30 h in culture. The cells that had undergone nuclear division were identified by their content of 2 or more nuclei. The long incubation period allowed slow growing V to be counted. As a result we scored an order of magnitude more V than have been reported in assays using the conventional 30-40 h culture times. In the gamma-ray dose range of 0-0.5 Gy we scored 80 V per 1000 surviving lymphocytes per Gy--a result some two orders of magnitude larger than has been reported previously.
Norman
A
A
Department of Radiological Sciences, University of California, Los Angeles 90024.
Mitchell
J C
JC
Iwamoto
K S
KS
D000328:Adult; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D004351:Drug Resistance; D005720:Gamma Rays; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects* / Q000528:radiation effects; D013866:Thioguanine / Q000494:pharmacology*
D013866:Thioguanine