title: Adaptation-like response to the chemical induction of sister chromatid exchanges in human lymphocytes.
abstract: Experiments have been performed to determine whether human lymphocytes in primary cultures can show an "adaptive" response to the induction of cellular lesions (manifested as a production of sister chromatid exchanges, SCEs) as previously found in bacteria and established human and mammalian cell lines. Human lymphocytes were pretreated with various subtoxic concentrations (5-50 ng/ml) of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) once every 6h for 72 h, and subsequently challenged by a high dose (4 micrograms/ml) of MNNG. The lymphocytes in MNNG-challenged cultures had the lowest frequency of SCEs when pretreated with 10 ng/ml MNNG. Further cross-resistance study revealed that repeated pretreatments of lymphocytes with 10 ng/ml MNNG for 72 h can render the cells resistant to the induction of SCEs by the following challenge with a high dose of MNNG, but not of mitomycin C or ethyl nitrosourea. The data also suggest variations in the degree of the adaptation-like response among individuals.
mesh_terms: D000220:Adaptation, Biological; D000477:Alkylating Agents / Q000633:toxicity*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D005038:Ethylnitrosourea / Q000633:toxicity; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000648:ultrastructure*; D008769:Methylnitronitrosoguanidine / Q000633:toxicity; D016685:Mitomycin; D008937:Mitomycins / Q000633:toxicity; D012854:Sister Chromatid Exchange / Q000187:drug effects*; D013997:Time Factors
chemical_list: D000477:Alkylating Agents; D008937:Mitomycins; D008769:Methylnitronitrosoguanidine; D016685:Mitomycin; D005038:Ethylnitrosourea