Enumeration of 6-thioguanine-resistant T-lymphocytes in the peripheral blood of nonhuman primates (cynomolgus monkeys)

We have investigated the use of cynomolgus monkeys (Macaca fascicularis) as a model of somatic cell mutagenesis in non‐human primates. Using techniques described by Albertini (Mutation Research 150:411–422, 1985) for similar studies in humans, the frequency of TG‐resistant T‐lymphocytes in the peripheral blood was determined in animals that were either untreated or treated with ethylnitrosourea. The frequency of TG‐resistant cells in untreated males was (mean ± 5D) 6.0 ± 5.9 per 106 cells and for untreated females was 2.9 ± 2.7 per 106 cells. The spontaneous frequency of TG‐resistant cells for all animals was 4.2 ± 4.44 per 106 cells. Maximum frequency of TG‐resistant cells for two animals treated with a single I.P. dose of ENU was 45.1 and 77.9 per 106 cells. Substantial increases in frequencies of TG‐resistant cells were not seen until at least 63 days after treatment. The TG‐resistant phenotype of clones isolated in the assay was stable after growth for 2 weeks in the absence of selective agent. Many of the TG‐resistant clones selected were frozen for future molecular analysis.