[The effect of activated pulmonary natural killer (NK) cells by poly I:C on the established pulmonary metastasis].

The author took interest in the existence of effector cells which had natural killer (NK) activity on the lung, in other words organ-associated NK cells, compared the augmented effect of pulmonary NK activity by poly I:C with that of spleen NK activity, and also investigated the effect of activated pulmonary NK cells on established pulmonary metastasis. It was shown that pulmonary NK cells in C57BL/6 mice had significant cytotoxicity against YAC-1 target cells in a 4 h-51Cr release assay, although their cytotoxicity was remarkably low as compared with that of spleen cells. However, by treatment with poly I:C, pulmonary NK activity was significantly augmented compared with spleen NK activity. This cytotoxicity was abrogated by treatment with anti-asialo GM1 antibody. From these results, it was considered that the effector cells was a NK cell. When poly I:C was administrated intraperitoneally from 3 days after intravenous inoculation of B16-F10 melanoma cells, the number of the pulmonary metastatic nodules was significantly decreased. The number of pulmonary metastatic nodules was not suppressed by a combination treatment of poly I:C and anti-asialo GM1 antibody to the same degree as in treatment by anti-asialo GM1 antibody alone. The experimental group which underwent a combination treatment of poly I:C and carrageenan showed a suppression of the number of pulmonary metastatic nodules to the same degree as the group treated with poly I:C alone. Therefore it was shown that the effect of pulmonary metastatic suppression with poly I:C was caused not by macrophages but by pulmonary NK cells.(ABSTRACT TRUNCATED AT 250 WORDS)