Lactobacilli Differentially Activate Natural Killer Cells

Lisbeth Nielsen Fink, Hanne Risager Christensen, Hanne Frøkiær

    Research output: Contribution to conferencePosterResearchpeer-review


    Bacteria translocating across the gastrointestinal mucosa are presumed to gain access to NK cell compartments, as consumption of certain lactic acid bacteria has been shown to increase in vivo NK cytotoxicity. On-going research in our lab aims at describing strain-dependent effects of lactic acid bacteria on regulatory functions of NK-cells. Here, we have investigated how human gut flora-derived non-pathogenic lactobacilli affect NK cells in vitro, by measuring proliferation and IFN-gamma production of human peripheral blood NK cells upon bacterial stimulation. CD3-CD56+ NK cells were isolated from buffy coats by negative isolation using non-NK lineage specific antibodies and magnetic beads. NK cells were incubated with 10 microg/ml UV-inactivated bacteria for four days. Proliferation was assessed by incorporation of radioactive thymidine into NK cell DNA and cytokine concentrations were determined by ELISA. Co-incubation of NK cells and a Lactobacillus acidophilus strain caused increased proliferation of the NK cells and induced IFN-gamma production. The proliferative response was further enhanced in the presence of autologous monocytes, probably because cytokines, secreted by monocytes having engulfed bacteria, stimulated the growth of the NK cells. In contrast, a Lactobacillus paracasei strain caused the NK cells to proliferate only in the presence of monocytes. These results demonstrate that various lactobacilli have the capacity to activate NK cells in vitro, in a monocyte dependent or independent way. Such activation of NK cells may potentially skew an on-going or subsequent immune response towards a Th1 response.
    Original languageEnglish
    Publication date2004
    Publication statusPublished - 2004
    Event20th International Natural Killer Cell Workshop - Noordwijkerhout, The Netherlands
    Duration: 1 Jan 2004 → …


    Conference20th International Natural Killer Cell Workshop
    CityNoordwijkerhout, The Netherlands
    Period01/01/2004 → …


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