Dual knockout of Fas and TCRα in Jurkat reporter cells enables highly sensitive identification of antigen-specific TCRs.

T-cell receptors (TCRs) that target tumor antigens are crucial for antitumor immunity; however, tumor-specific TCRs often exhibit low affinity for their cognate antigens, making the identification of functional TCRs challenging due to the limited sensitivity of current detection methods. In this study, we established a high-sensitivity TCR screening platform by generating Jurkat cell reporter clones with dual knockout (DKO) of endogenous Fas and TCRα via CRISPR-Cas9 system. In a viral antigen model system, these DKO Jurkat cells exhibited approximately 100-fold greater sensitivity to antigen stimulation compared with parental Jurkat cells. Notably, our DKO Jurkat-based platform enabled the identification of tumor-specific CD8+ T cells from a lung cancer patient that could not be detected using parental Jurkat cells. Moreover, the identified tumor-specific T-cell clone exhibited a unique phenotype characterized by robust cytotoxic T lymphocyte (CTL) activity and natural killer-like properties. Together, these findings demonstrate that dual deletion of Fas and TCRα in Jurkat cells enables highly sensitive functional TCR screening. Integration of this platform with single-cell analysis facilitates the discovery of previously uncharacterized tumor-reactive TCRs and provides a powerful tool for advancing TCR-based cancer immunotherapy.