[Role of asialo GM 1 positive cells in the control of metastatic spread of tumor cells in mice].

The role of asialo GM1 positive cells was studied in artificial and spontaneous pulmonary metastases as well as in tumor growth by using B-16 melanoma cells in C57BL/6 mice. Single administration of 50 microliters of anti-asialo GM1 antibody resulted in the significant decrease of NK activity in the spleen cells of C57BL/6 mice lasting 13 days from the following day of administration. The anti-asialo GM1 antibody was evaluated in terms of for its effect on pulmonary metastases with regard to the timing of administration. Treatment with anti-asialo GM1 antibody 1 day before or on the day of tumor inoculation resulted in a substantial increase in the number of artificial pulmonary metastases. In the experimental system of spontaneous metastases, the anti-asialo GM1 antibody most effectively increased the number of pulmonary metastases when administered 1 to 2 weeks before the amputation of the tumor primary site. In addition, in mice treated with anti-asialo GM1 antibody, the acceleration of the growth of the transplanted tumor was observed. These results strongly suggest that asialo GM1 positive cells not only inhibit pulmonary metastases acting mainly on circulating tumor cells but also suppress the growth of transplanted tumor.