How T cell receptor (TCR) signal strength modulates T cell function and to what extent this is modified by immune checkpoint blockade (ICB) are key questions in immunology. Using Nr4a3-Tocky mice, we characterized early quantitative and qualitative changes that occur in CD4⁺ T cells in relation to TCR signaling strength. We captured how dose- and time-dependent programming of distinct co-inhibitory receptors rapidly recalibrates T cell activation thresholds and visualized the immediate effects of ICB on T cell re-activation. Our findings reveal that anti-PD1 immunotherapy leads to an increased TCR signal strength. We defined a strong TCR signal metric of five genes upregulated by anti-PD1 in T cells (TCR.strong), which was superior to a canonical T cell activation gene signature in stratifying melanoma patient outcomes to anti-PD1 therapy. Our study therefore reveals how analysis of TCR signal strength—and its manipulation—can provide powerful metrics for monitoring outcomes to immunotherapy.

T 细胞受体 (TCR) 信号强度如何调节 T 细胞功能以及免疫检查点阻断 (ICB) 在多大程度上改变 T 细胞功能是免疫学中的关键问题。使用Nr4a3 -Tocky 小鼠，我们表征了 CD4 ⁺ T 细胞中发生的与 TCR 信号强度相关的早期定量和定性变化。我们捕获了不同共抑制受体的剂量和时间依赖性编程如何快速重新校准 T 细胞激活阈值，并可视化 ICB 对 T 细胞重新激活的直接影响。我们的研究结果表明，抗 PD1 免疫疗法可增强 TCR 信号强度。我们定义了 T 细胞中抗 PD1 上调的 5 个基因的强 TCR 信号指标 (TCR.strong)，该指标在对黑色素瘤患者的抗 PD1 治疗结果进行分层方面优于典型的 T 细胞激活基因特征。因此，我们的研究揭示了 TCR 信号强度的分析及其操作如何为监测免疫治疗的结果提供强有力的指标。