Figure 5. Antigen-specific TCR transgenic cTfh cells display similar phenotypic characteristics and kinetics to endogenous alloreactive cTfh cells following transplantation.

(A) Naïve B6 mice were adoptively transferred 10⁶ of each Thy1.1⁺ CD4⁺ OT-II and CD8⁺ OT-I T cells, transplanted skin from B6 (Syn) or mOVA donors and sacrificed at indicated time points post-transplantation for PBMC, graft-dLN and serum analyses. (B) Flow plots (gated on CD4⁺Foxp3⁻ T cells) depict gating strategy for CXCR5⁺Thy1.1⁺ OVA-specific cTfh cells. (C) Summary data of Thy1.1⁺ cTfh cell frequencies and numbers following B6 (Syn) or mOVA skin transplantation over time (n=5 per group). (D) Summary data of phenotypic marker expression in naïve (CD44^loCD62L⁺) OT-II cells, and Thy1.1⁺ CXCR5⁻ or CXCR5⁺ OT-II cells from the peripheral blood 10 days post-transplantation (n=5 per group). (E) Flow plots depicting ICOS and PD-1 expression on naive OT-II cells on day 0 and Thy1.1⁺CXCR5⁺ cTfh cells 10 days post-transplantation. (F) Summary data of the frequencies of ICOS⁺PD-1⁺ of naïve OT-II cells on day 0 and Thy1.1⁺ cTfh cells 10 days after transplant (n=5 per group). (G) Summary data of ICOS⁺PD-1⁺ Thy1.1⁺ cTfh cell frequencies over time (n=5 per group). Summary data of (H) Thy1.1⁺ cTfh cell and (I) ICOS⁺PD-1⁺ Thy1.1⁺ cTfh cell frequencies relative to anti-OVA IgG formation over time (n=5 per group). Summary data represent mean (SE) and are representative of three independent experiments with a total of 10–15 mice per group. *p < 0.05, **p < 0.01, ***p< 0.001.