Affiliation:
1. Yakult Central Institute for Microbiological Research, 1796 Yaho, Kunitachi, Tokyo 186-8650, Japan
Abstract
ABSTRACT
We examined the effect of a probiotic strain,
Lactobacillus casei
strain Shirota, on cytokine production and natural killer (NK) cell activity in human peripheral blood mononuclear cells (PBMNC). The cellular mechanisms of immunoregulation by
L. casei
strain Shirota were also investigated.
L. casei
strain Shirota stimulated PBMNC to secrete interleukin-12 (IL-12), gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), and IL-10. However, depletion of monocytes from PBMNC eliminated the induction of these cytokines.
L. casei
strain Shirota was phagocytosed by monocytes and directly stimulated them to secrete IL-12, TNF-α, and IL-10. IFN-γ production was diminished by the addition of anti-IL-12 antibody to the PBMNC cultures. Purified T cells, but not NK cells, produced IFN-γ effectively when stimulated with
L. casei
strain Shirota in the presence of monocytes, indicating that monocytes triggered by
L. casei
strain Shirota help T cells to produce IFN-γ through secreting IL-12. In addition, NK cell activity and CD69 expression on NK cells increased after cultivation of PBMNC with
L. casei
strain Shirota. When monocytes were depleted from PBMNC,
L. casei
strain Shirota did not enhance NK cell activity. These results demonstrate that monocytes play critical roles in the induction of cytokines and following the augmentation of NK cell activity during the stimulation of human PBMNC with
L. casei
strain Shirota.
Publisher
American Society for Microbiology
Subject
Microbiology (medical),Clinical Biochemistry,Immunology,Immunology and Allergy
Cited by
70 articles.
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