The effect of microbial flora, diet, and age on the tumoricidal activity of natural killer cells.
This study examined the effects of diet (chemically defined vs natural-ingredient), age, and microbial flora on the tumoricidal activity of natural killer (NK) cells from the spleens of mice. Results from a 4-h 51Cr-release assay indicate the following: Germfree C3H/HeCr mice raised on a chemically defined diet had significantly greater NK cell activity than their germfree or "clean-conventional" (i.e., barrier-maintained) counterparts who were raised on a sterilized natural-ingredient diet. The NK activity of germfree mice was dramatically increased after their alimentary tract was colonized with a complex intestinal flora. Conventional mice raised under clean (barrier) conditions had significantly less NK cell activity than nonbarrier-maintained mice. Switching germfree mice from a chemically defined diet to a sterile natural-ingredient diet did not enhance NK cell activity. No significant differences in NK activity were evident with C3H/HeCr mice of different (6-10 wk vs 29-36 wk) ages. These results indicate that diet and microbial flora can modulate the NK cell activity of mice.
D000375:Aging; D000818:Animals; D002860:Chromium Radioisotopes; D003602:Cytotoxicity, Immunologic; D004032:Diet; D005260:Female; D005856:Germ-Free Life; D007422:Intestines / Q000382:microbiology*; D007694:Killer Cells, Natural / Q000276:immunology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D013154:Spleen / Q000166:cytology / Q000254:growth & development* / Q000276:immunology
D002860:Chromium Radioisotopes