Genotoxicity Of The Gas/Vapor Phase (GVP) Of Cigarette Mainstream Smoke In The Mouse Lymphoma TK Assay (MLA)

The in vitro mammalian mutagenicity of cigarette smoke by means of the Mouse Lymphoma TK assay (MLA) is generally assessed by assaying the particulate phase only (Schramke et al., 2006). In order to generate a comprehensive and thus more relevant image of cigarette-smoke-related mammalian mutagenicity in vitro we extended this approach to the water-soluble fraction of the gas/vapor phase (GVP). The GVP of mainstream smoke from the reference cigarette 3R4F was assayed in the microtiter plate version (Cole et al., 1986) of the MLA with and without metabolic activation (S9), after 4 and 24 hours of treatment time and 2 and 3 days of expression time. Dose response: a clear-cut positive dose-response relationship was seen regardless of activation conditions, treatment time, and expression time. Variability of mutant frequency: For the 24-h treatment time (without S9, 2 days expression), mean repeatability was 16% and mean reproducibility was 26%. For the 4-h treatment time (with and without S9, 3 days expression), mean repeatability was 12% and mean reproducibility was 15%. Variability of 1/C3B values: For the 24-h treatment time (without S9, 2 days expression), repeatability was 6% and reproducibility was 8%. For the 4-h treatment time (with and without S9, 3 days expression), mean repeatability was 3% and mean reproducibility was 5%. Thus, the results showed that the MLA is sensitive for the detection of the in vitro mammalian mutagenicity of the gas/vapor phase of cigarette mainstream smoke.