Fig 2: Transient dose‐dependent Treg depletion. AB1‐HA bearing BALB/c FoxP3.dtr mice treated with indicated doses of DTX on days 9 and 10. Treg‐specific depletion in peripheral blood shown 1 (DTX+1) and 4 (DTX+4) days after DTX administration. (A) Experimental design. (B) DTX dose‐dependent depletion of Treg at DTX+1. (C) Survival outcome. (D) Rebound of T cell subsets and (E) T cell activation (ICOS) and (F) proliferation (Ki67) status four days after transient DTX‐mediated Treg depletion. Representative data from three independent experiments showing mean (n = 5/group) ± SEM. CD4 (open circle) and CD8 (open square) as proportion of total lymphocytes. Treg (closed diamond) as proportion of total CD4 T cells. Log rank (Mantel–Cox) analysis was performed on survival curves. Mann–Whitney U‐test for comparisons between two groups. *P < 0.05, **P < 0.01, ***P < 0.001. UT, untreated; Tu, (AB1‐HA) tumor cells.

Fig 3: Intratumoral ICOS Agonistic (Apt8a) Treatment in Combination with CTLA-4 Blockade Promotes Antitumor Immune Response(A) B16/F10 melanoma tumor-bearing mice were treated with ICOS Apt8a intratumorally as well as anti-CTLA-4 antibody intraperitoneally on days 4, 7, and 10, and splenocytes were extracted at day 14 and then cocultured with B16/F10 irradiated cells. As measurement of T cell activation, proliferation was assessed by 3H incorporation (B) and IFN-? production by ELISPOT (C) and ELISA (D). (Data are expressed as the mean ± SEM of three mice per group. Experiments were repeated twice with similar results.) *p < 0.05, ***p < 0.005.

Fig 4: Intratumoral ICOS Agonist (Apt8a) Potentiates CTLA-4 Blockade Therapy in a Melanoma Mouse Model(A) B16/F10 melanoma tumors were implanted subcutaneously in C57/BL6 mice. On days 4, 7, and 10 after tumor implantation, mice were injected intraperitoneally (i.p.) with CTLA-4 blocking antibody (9H10) and intratumorally (i.t.) with Apt8a or Apt ctrl to evaluate tumor growth and survival. (B) Tumor growth kinetics was measured by calipers, and tumor volume was determined using the formula W2 × L/2; W is tumor width, and L is tumor length. The average tumor size of each group of mice treated is shown. Data are expressed as the mean ± SEM. **p < 0.01, ***p < 0.005. (C) Percentage of tumor volume change of each mouse once the treatment is initiated (isotype control in black, Apt ctrl with CTLA-4 antibody in gray, and Apt8a with CTLA-4 antibody in red). (D) Overall survival of mice treated with anti-anti-CTLA-4 antibody and Apt8a or Apt ctrl as described in the calendar. (Experiments were repeated twice with similar results.) *p < 0.05, **p < 0.01.

Fig 5: ICOS deficiency impairs the expression of reparative MoMF markers during the evolution of acute liver injury. The transcripts of reparative MoMF markers CD206, MerTK, and TREM-2 were evaluated by Real-Time PCR in the liver of wild-type and ICOS-/- mice at different time points following the administration of CCl4. The vertical dotted boxes indicate statistically significant differences between wild-type and ICOS-/- mice at each time point. The results are expressed as mean ± SD of 5-8 animals for each time point.