Supplementation with the probiotic strain Weissella cibaria JW15 enhances natural killer cell activity in nondiabetic subjects

The aim of this study was to investigate the impact of consuming Weissella cibaria (W. cibaria) JW15 on natural killer (NK) cell activity, cytokines and immunoglobulins (Igs). This randomized, double-blinded, placebo-controlled study enrolled 100 nondiabetic participants. For eight weeks, the probiotic group consumed capsules containing 1 × 10¹⁰ colony forming units (cfu) of W. cibaria JW15 daily, whereas the placebo group consumed the same capsules without a probiotic. NK cell activity at effector cell (E; peripheral blood mononuclear cells, PBMCs):target cell (T; K562 cells) ratios of 10:1, 5:1, 2.5:1, or 1.25:1 was significantly increased in the probiotic group compared to the placebo group at 8 weeks after baseline. The probiotic group had significantly greater increases in NK cell activity than the placebo group under all assay conditions. Daily consumption of the W. cibaria JW15 probiotic effectively enhanced immune functions by increasing NK cell activity (Clinicaltrials.gov; NCT03209635).