The signaling symphony: T cell receptor tunes cytokine-mediated t cell differentiation

T cell development, differentiation, and maintenance are orchestrated by 2 key signaling axes: the antigenspecific TCR and cytokine-mediated signals. The TCR signals the recognition of self- and foreign antigens to control T cell homeostasis for immune tolerance and immunity, which is regulated by a variety of cytokines to determine T cell subset homeostasis and differentiation. TCR signaling can synergize with or antagonize cytokinemediated signaling to fine tune T cell fate; however, the latter is less investigated. Murine models with attenuated TCR signaling strength have revealed that TCR signaling can function as regulatory feedback machinery for T cell homeostasis and differentiation in differential cytokine milieus, such as IL-2-mediated T_reg development; IL-7- mediated, naïve CD8⁺ T cell homeostasis; and IL-4- induced innate memory CD8⁺ T cell development. In this review, we discuss the symphonic cross-talk between TCR and cytokine-mediated responses that differentially control T cell behavior, with a focus on the negative tuning by TCR activation on the cytokine effects.