扁桃由来リンパ球の姉妹染色分体交換--その誘発因子と医学生物学的考察
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概要
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Using primarily and continuously cultured lymphocytes from tonsils, various factors causing the changes of occurrence in sister chromatid exchanges (SCE) together with the chromosomal aberrations (CA) were examined. The most optimal culture conditions for the SCE observation were studied in primary tonsillar lymphocytes and determined as follows: The number of cells at initiation was; 2 X 106 cells/ml, the culture medium was RPMI-1640 containing 20% fetal calf serum, 15pg/ml of phytohemagglutinin-P and 1011g/ml of 5-bromodeoxyuridine (BUdR) ; the incubation period was 72 hours at 37-C. During 72 hours, the most of cells performed two rounds of DNA replication and showed the metaphases in which each chromosome had one chromatid unifilarly substituted with BUdR and one bifilarly. These cells were submitted to the fluorescence plus Giemsa technique (FPG) for the SCE observation following the usual procedures for chromosomal analysis (flame-drying method). The mean number of SCE in primary tonsillar lymphocytes from 13 patients showing tonsillar hypertrophy or recurrent tonsillitis without inflammatory signs was 5. 134-0.16 SCEs/cell, while 6.57-0. 15 SCEs/cell in 14 patients with chronic inflammatory tonsils. No significant changes of the SCE scores related to the ages, the grades of hypertrophy and the mitotic indices were observed. In the case of tonsillar lymphocytes infected by Epstein-Barr virus (EBV), the SCE scores showed the similar values to those in the chronic tonsillitis. The treatment of these cells with an antitumor drug (mitomycin C), u chemical mutagen (4-nitroquinoline 1-oxide) and the irradiation with ultraviolet light induced significantly the increases of SCE scores before the chromatid breaks occured. Caffein known as the specific inhibitor for DNA repair enzyme increased the breaks without the SCE changes. Nicotine which seems to be related to generation of lung cancer did not show any effects on the SCE or break changes even at 10-3 M. The infection by several DNA-viruses (adeno type 5 and 12, cowpox) or RNA-viruses (rubella, Sendai and Coxsackie B-5), which induced oral or upper respiratory tract infection did not cause the significant changes of SCE scores. However, it resulted in the increases of the breaks before the viral cytopathogenic effect was appeared. These results seem to indicate that the analysis of SCE and CA in tonsillar lymphocytes may be a useful procedure for the follow-up of the minor action of chemical mutagens and the initial change by viral infection with the other cellular responses.
- 社団法人 日本耳鼻咽喉科学会の論文