Mice 1.2.3 Growth and Metastasis:

ABSTRACT-The role of natural killer (NK) cells in tumor growth and metastasis was studied in syngeneic normal and beige inbred C57BLl6 mice. Mice with the beige point mutation have been shown to be deficient in nonstimulated NK activity. Tumor-passaged B16 malignant melanoma cells were refractory to NK activity as determined by in vitro assay, but after in vitro culture they became sensitive to NK activity. The NK-insensitive B16 tumor grew and metastasized similarly in normal and beige mice. However, the NK-sensitive B16 tumors grew more slowly and produced fewer metastases in normal mice than in NK-deficient beige mice. Activation of NK cells by lymphocytic choriomeningitis virus infection decreased the rate of growth and number of metastases of both NK-sensitive and NK-insensitive tumors in both normal and beige mice. These results suggest the importance of NK cells as a determinant of tumor growth an