Figure 2

Butyrate impairs the production of inflammatory cytokines by human NK cells. PBMC were cultured for 18 h with or without IL-12 (30 ng/mL) and IL-15 (100 ng/mL). Butyrate (1 mM) was added where indicated for the duration of the experiment. Cytokine production was assessed by intracellular cytokine staining with Golgi-plug added to cultures for the final 3 h. Representative dot plots and individual paired data (with/without butyrate) of frequency and expression (MFI) of cytokines by CD56^bright cells (left panel) or CD56^dim cells (right panel) (n = 10) (a,b) IFNγ, (c,d) TNF-α, (e,f) IL-22, (g,h) Granzyme B. NK cells were purified by negative selection and cultured as described above. Cytokine concentration in the supernatant was measured using BioLegend’s LEGENDplex bead-based immunoassay. (i) TNF-α, sFasL (soluble Fas ligand), IFNγ, granzyme A, granzyme B, perforin (n = 6). Bars show the average value ± SEM. Samples were compared using the Wilcoxon signed rank test. *p < 0.05, **p < 0.01, ***p < 0.001.