Figure 2. Hybrid Th1/17 Cells Exhibit Superior Anti-Tumor Response.

(A) Schematic presentation of the experimental strategy (left panel) and the differences observed in tumor growth (right panel) when subcutaneously established B16-A2 tumor in HLA-A⁺ mice (n = 8 mice/group) were treated by adoptively transferring tyrosinase reactive TIL1383I TCR transgenic T cells differentiated to Th1, Th17, and hybrid Th1/17 cells. Data demonstrate mean tumor size at each time point in one of the three experiments with similar results.

(B) C57BL/6 mice with 10 day subcutaneously established B16-F10 melanoma tumor were either kept untreated or treated by transferring 0.5 × 10⁶ TRP-1 Th1/17 cells. The treated group was subdivided to administer 100 μg neutralizing antibody against IFNγ, IL17, or isotype control Ab intraperitoneally every alternate day. Tumor growth curve for various groups with n = 4 is shown.

(C) C57BL/6 Ly5.1⁺ recipients were injected (i.v.) with 0.5 × 10⁶ luciferase-transduced B16-F10 (B16-Fluc) and following lympho-depletion (sub-lethally irradiation with 500 cGy) on day 6. Groups of mice were adoptively transferred with either 0.25 × 10⁶ TRP-1 Th1, Th17, or Th1/17 cells on day 7. Survival and tumor growth (left panel) were followed with bioluminescent imaging. On day 80, recipient mice were re-challenged by injecting 0.5 × 10⁶ B16-Fluc tumors. Survival and tumor growth were followed until day 150 by bioluminescent imaging (upper right). Lower right panel shows that mice receiving hybrid Th1/17 developed a strong vitiligo on the skin.

(D) Representative flow panel showed tumor-infiltrating lymphocytes (TILs) recovered from lung on day 150 from Ly5.1⁺ recipient mice and re-stimulated with PMA and Ionomycin for 4 hr in vitro to measure IFNγ and IL17 secretion. ****p < 0.0001. Also see Figures S2 and S3.