Figure 1: TIGIT agonism combined with CTLA-4Ig prolongs allograft survival, increases graft-infiltrating Treg while reducing graft-infiltrating CD8⁺ T cells.

. (A) Schematic of experimental design. Thy1.1⁺ TCR transgenic OT-I and OT-II T cells are adoptively transferred into naive C57BL/6 hosts 24 h prior to grafting with OVA expressing skin. Animals are subsequently treated with PBS, TIGIT agonist (250ug), CTLA-4Ig (250ug) or a combination of CTLA-4Ig + TIGIT agonist on days 0, 2, 4, and 6 after transplant. Allograft survival was monitored after skin graft and cessation of immunosuppression (B). Skin graft tissue was also collected 10 days after allograft challenge and digest to determine the infiltrating lymphocyte populations (C-I). Representative flow cytometry plots and summary data for the bulk CD4⁺ T cell population (C, D left panel) bulk CD8⁺ T cell population (C, E right panel) from skin graft tissue are shown. Thy1.1⁺ OT-I T cells within the CD8⁺ T cell compartment were detected and quantified (representative flow F, summarized G). Treg were detected within the CD4⁺ T cell compartment off the grafted tissue (represented in H, summarized I). Summary of graft survival data pooled from three independent experiments. Flow cytometry data are representative of 3 independent experiments (n=20 per group) mean ± SEM is shown. Non-parametric Mann-Whitney T tests were performed (*p<0.05, **p<0.01, ***p<0.001, ****p<0.0001).