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SFTG international collaborative study on in vitro micronucleus test II. Using human lymphocytes.
M Gillian Clare1, Giocondo Lorenzon, Leslie C Akhurst
1Department of Genetic Toxicology, Safety Assessment, Astra Charnwood, Loughborough, Leics, UK. gillian.clare@covance.com
Mutation Research
|June 13, 2006
Summary
This in vitro micronucleus assay study found that human lymphocytes can detect genotoxic compounds. Protocol refinements are needed to improve sensitivity for detecting clastogenic and aneugenic potential.
Area of Science:
- Genotoxicity testing
- In vitro toxicology
- Human lymphocyte assays
Background:
- The in vitro micronucleus assay is a key method for assessing genotoxicity.
- Standardization and optimization are crucial for reliable results in inter-laboratory studies.
Purpose of the Study:
- To evaluate the ability of human lymphocytes in vitro to detect micronucleus induction by various chemicals.
- To assess the reproducibility and sensitivity of the in vitro micronucleus assay across multiple laboratories.
Main Methods:
- Eleven laboratories participated in a collaborative study using human lymphocytes.
- Nine coded substances, including a positive control (mitomycin C), were tested under various exposure and recovery conditions with cytochalasin B.
- Data were analyzed for acceptability and classified as negative, positive, or equivocal.
Main Results:
- Colchicine and bleomycin were clearly identified as micronucleus inducers.
- Cytosine arabinoside, diethylstilbestrol, and 5-fluorouracil yielded equivocal results, requiring repeat testing.
- Urethane, thiabendazole, mannitol, and clofibrate were classified as negative.
- No false positive results were observed, indicating high specificity.
Conclusions:
- The in vitro micronucleus assay using human lymphocytes demonstrated accuracy in identifying clastogenic and aneugenic potential.
- Optimizing protocols, including cell cycle exposure and recovery times, can enhance assay sensitivity.
- Evaluating micronuclei in both mononucleated and binucleated cells aids in aneugen detection.