FIG 1.

Vα19iTg T cells produce IFN-γ in response to recombinant IL-12, IL-12 + IL-18, and IL-12 + IL-33 in the absence of cognate antigen. Naive Thy1.2⁺ cells purified from Vα19iTgCα^−/− MR1^+/+ mice were cultured for 20 h in the presence of recombinant cytokines, as indicated. (A) ELISA analysis of IFN-γ production by Vα19iTg T cells in the culture supernatants. (B) Flow cytometry analysis of Vα19iTg T cell IL-18Rα expression after treatment with recombinant IL-12. Results show reactivity to MR1-5-OP-RU tetramer (MR1 tetramer). The percentages of IL-18Rα⁺ cells for the 5-OP-RU MR1 tetramer⁺ (Tet⁺) and tetramer⁻ (Tet⁻) populations are depicted graphically. (C and D) IFN-γ intracellular cytokine staining of Vα19iTg T cells cultured for 20 h in the presence of recombinant cytokines, as indicated. The percentages of intracellular IFN-γ⁺ cells for the 5-OP-RU MR1 tetramer⁺ and tetramer⁻ populations are depicted graphically. Brefeldin A was added during the final 4 h of culture. All flow cytometry dot plots depict TCRβ⁺ lymphocytes with B220⁺ and F4/80⁺ cells excluded by electronic gating. No treatment, culture medium without recombinant cytokines; isotype Ab, intracellular cytokine staining using a nonspecific control Ab. Data represent values ± standard errors of the means (SEM) from three replicates and are representative of three independent experiments. *, P < 0.05 compared to “No treatment”; **, P < 0.05 compared to IL-12.