Susceptibility of various strains of mice to urethan-induced lung tumors and depressed natural killer cell activity
Gorelik, E.; Herberman, R.B.
Journal of the National Cancer Institute 67(6): 1317-1322
1981
ISSN/ISBN: 0027-8874 PMID: 6947114 Document Number: 175492
Inbred A/J, CBA/J and c57BL/6 mice at age 7-8 wk were inoculated with 1 mg urethan/g body wt. Three months later, 13.2, 1.8, and 0.1 tumors per lung were found in these mice, respectively. Cytotoxicity by spleen cells of normal and urethan-treated mice was analyzed in a 4-h 51Cr release assay against YAC-1 -deoxyuridine-labeled YAC-1 cells. Urethan caused profound and sustained suppression of in vivo NK reactivity in the lungs of A/J mice had only a transient effect on CBA/J mice, and had no detectable effect on C57BL/6 mice. The differences in the effects of urethan on the natural antitumor resistance in the 3 strains of mice could not be attributed to a generally greater susceptibility of A/J mice to inhibition of NK activity, since cyclophosphamide (0.15 mg/g) equally suppressed the clearance from the lungs of the radiolabeled tumor cells in A/J, CBA/J and c57BL/6 mice. These results indicate a positive correlation between susceptibility of A/J, CBA/J, and C57BL/6 mice to urethan-induced lung carcinogenesis and inhibition of in vitro and in vivo natural cell-mediated cytotoxicities. NK cells may play a role in resistance to urethan- induced lung carcinogenesis.