Fig.4. Supernatants from PBMCs treated with P. acnes differentiate naïve CD4⁺T cells to IL-17 producing T cells.

a) PBMCs (2–5 × 10⁶/ml) were stimulated overnight with P. acnes sonicate (2 µg/ml). Culture supernatants were then collected and used to stimulate naive CD4⁺CD45RA T cells for seven days in 96 well plates with plate bound anti-CD3 and soluble CD28. Cells were harvested and intracellular cytokine staining for IL-17 was performed. Each panel is representative of three independent experiments. b) PBMCs (2–5 × 10⁶/ml) were cultured with IL-17, IL-1β, IL-6, TGF-β, IL-23p19, IL-4 and IFN-γneutralizing antibodies for one hour followed by seven days of stimulation with P. acnes. IL-17 production was then measured using ELISA. Data are representative of four independent experiments. Data represent mean ± SD (** p ≤ 0.05, ***p ≤ 0.001)