Alterations in splenic natural killer cell activity induced by the Shionogi mouse mammary tumor

We have previously demonstrated that differential housing conditions alter the growth rate of the Shionogi mouse mammary carcinoma (SC115). The present study was undertaken to determine if natural killer (NK) cells are involved in mediating the effects of differential housing on SC115 tumour growth rate. Splenic NK cell activity was assayed at 24 h, 3 days and 1 week post-injection in both tumour- and vehicle-injected animals. Significant stimulation of splenic NK cell activity occurred 3 days post-injection of SC115 cells. However, no correlation was observed between the level of splenic NK cell activity and tumour growth rate induced by housing condition. We conclude that either splenic NK cell activity does not accurately reflect NK cell activity at the tumour site or that NK cells are not a significant regulator of the differential tumour growth rates seen in this model.