Figure 5. Inflammatory cytokines and TCR-mediated signals synergize to induce MAIT cell effector function.

(A) Monocytes were stimulated with ssRNA (a TLR8 agonist); after 24 hours, supernatant was removed and CD8⁺CD161^hiCCR6^hi MAIT cells were cocultured with TLR8 supernatant in the presence (TLR8 sup + TCR, dark green) or absence (TLR8 sup only, light green) of anti-CD3/CD28 beads for 24 hours followed by analysis of IFN-γ and granzyme B expression (n = 3). MAIT cells stimulated only with anti-CD3/CD28 (TCR only) beads for 24 hours are shown in black. (B) Using the same donors and experimental setup as in A, monocytes were stimulated with LPS (a TLR4 agonist) in the presence (TLR4 sup + TCR, dark blue) or absence (TLR4 sup only, light blue) of anti-CD3/CD28 beads for 24 hours followed by analysis of IFN-γ and granzyme B expression (n = 3). MAIT cells stimulated only with anti-CD3/CD28 (TCR only) beads for 24 hours are shown in black. (C) Luminex analysis of statistically significant analytes (left panel) or from the cytokines IL-12, IL-15, and IL-18 (right panel) from supernatant collected from CD14⁺ monocytes that were rested (white bars) or activated with LPS (TLR4, light blue bars) reveal differences in cytokine expression dependent on stimulation (n = 4). A lack of a visible error bar in C (right panel) is due to identical data points. Data are displayed as mean ± SEM (where applicable).*P ≤ 0.05. P values were determined by comparing treatment conditions to unstimulated or TCR-only conditions using Mann-Whitney 1-tailed or 2-tailed U test (A–C).