Skin-resident γδ T cells mediate potent and selective antitumor cytotoxicity through directed chemotactic migration and mobilization of cytotoxic granules.

Dendritic epidermal T cells (DETCs) are a unique subset of γδ T cells that reside predominantly in mouse epidermis, yet their antitumor functions remain enigmatic. Here we report that DETCs mediate potent and exquisitely selective cytotoxicity against diverse tumor types while sparing healthy cells. In vitro, DETCs induced apoptosis in melanoma, hepatoma, colon carcinoma and lymphoma lines in a dose- and time-dependent manner that required direct cell-cell contact. In vivo, adoptive DETC transfer significantly suppressed melanoma growth and metastasis while prolonging survival. Mechanistically, DETCs upregulated perforin/granzyme B expression upon tumor recognition, and inhibition of this pathway ablated cytotoxicity. DETCs selectively homed to and formed intimate contacts with tumor cells in vivo through directed chemotaxis and aggregation. Tumor engagement triggered pro-inflammatory DETC activation while dampening immunosuppressive factors in the microenvironment. Notably, mTOR signaling coupled tumor recognition to DETC trafficking, cytotoxicity and inflammatory programs, as rapamycin treatment impaired effector functions and therapeutic efficacy. Collectively, these findings establish DETCs as multidimensional antitumor effectors and provide insights for harnessing their unique biology for cancer immunotherapy.