The increase of a normally occurring K cell population during progressive tumor growth in mice

K cell activity of the spleen cells from normal and tumor-bearing mice was compared using an antibody-dependent cellular cytotoxicity assay. The K cell activity increased with progressive tumor growth (syngeneic) compared to the K cell activity of normal mice. The increase in K cell activity most likely reflected an increase in the numbers of K cells normally present in nontumor-bearing mice rather than the emergence of a distinct population of K cells induced by the growing tumor.