FIGURE 3.

Conversion of Tregs into IL-17–producing cells requires TGF-β and IL-1β. A, Tconvs and Tregs were cultured with anti-CD3 mAb and APCs. TGF-β neutralizing Ab or isotype control was added, and production of IL-17A was measured on day 3. *p = 0.003. Representative results of four experiments are shown. B, Tconvs and Tregs were cultured with anti-CD3 mAb and APCs, either individually or mixed at a 1:1 ratio, and IL-6 was measured. C, Tconvs and Tregs were mixed at a 1:1 ratio, cultured with anti-CD3 mAb and APCs in the presence of media, anti-IL-6 neutralizing Ab, anti-IL-6 receptor blocking Ab, or their combination, and IL-17A was assessed. Representative results of three experiments are shown. D, Tconvs and Tregs were cultured with anti-CD3 mAb and APCs in the absence or presence of IL-1β neutralizing Ab. Results are representative of four experiments. E, Tc^WT or Tc^KO were cultured with Tregs from Tr^WT or from Tr^KO with anti-CD3 mAb and APCs, and production of IL-17A was assessed on day 3. Representative results of two experiments are shown. Tc^KO, Tconvs from IL-1R1^−/− mice; Tc^WT, Tconvs from wild type mice; Tr^WT, Tregs from wild type mice; Tr^KO, Tregs from IL-1R1^−/− mice.