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Interleukin-12 is involved in the enhancement of human natural killer cell activity by Lactobacillus casei Shirota

2006; Oxford University Press; Volume: 146; Issue: 1 Linguagem: Inglês

10.1111/j.1365-2249.2006.03165.x

1365-2249

Kazuyoshi Takeda, T Suzuki, S-I Shimada, K. Shida, M Nanno, Ko Okumura,

Probiotics and Fermented Foods

Summary We conducted a placebo-controlled, cross-over trial to examine the effect of Lactobacillus casei Shirota (LcS) on natural killer (NK) cell activity in humans. NK cell activity exhibited a declining trend during the period of placebo ingestion, but NK cell activity increased after intake for 3 weeks of fermented milk containing 4 × 1010 live LcS. When human peripheral blood mononuclear cells were cultured in the presence of heat-killed LcS, NK cell activity was enhanced. The ability of LcS to enhance NK cell activity and induce interleukin (IL)-12 production was correlated, and the addition of anti-IL-12 monoclonal antibody reduced the enhancement of NK cell activity triggered by LcS. In addition, separation of NK cells from LcS-stimulated monocytes with membrane filter reduced NK cell activity to the intermediate level and almost deprived monocytes of the ability to produce IL-12. These results demonstrate that LcS can enhance NK cell activity in vivo and in vitro in humans, and IL-12 may be responsible for enhancement of NK cell activity triggered by LcS.