Natural defense systems of fasting rats against tumor cells

The effect of fasting on naturally cytotoxic cells in rat liver and rat spleen was investigated. Neither fasting 100% (nor 50%) for eight days nor 100% overnight significantly reduced this natural cytotoxicity. Target cells YAC-1, P815, and WEHI-164 cells were used in a chromium release assay. Assuming that YAC-1 cells are preferentially killed by "true" natural killer cells, P815 by macrophages, and WEHI-164 by so-called natural cytotoxic cells, our results indicate that none of these subsets of naturally cytotoxic cells are hampered or stimulated by the fasting regimens used.