title: Interleukin-12 is involved in the enhancement of human natural killer cell activity by Lactobacillus casei Shirota.
abstract: 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 x 10(10) 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.
authors.affiliation: Department of Immunology, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Takeda
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: S-I
authors.initials: SI
authors.lastname: Shimada
authors.forename: K
authors.initials: K
authors.lastname: Shida
authors.forename: M
authors.initials: M
authors.lastname: Nanno
authors.forename: K
authors.initials: K
authors.lastname: Okumura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002450:Cell Communication / Q000276:immunology; D002478:Cells, Cultured; D018592:Cross-Over Studies; D043302:Cultured Milk Products / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D005260:Female; D005285:Fermentation; D006801:Humans; D018664:Interleukin-12 / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D007780:Lacticaseibacillus casei / Q000276:immunology*; D008297:Male; D019936:Probiotics
chemical_list: D018664:Interleukin-12