NKG2D controls natural reactivity of Vγ9Vδ2 T lymphocytes against mesenchymal glioblastoma cells.

Purpose: Cellular immunotherapies are currently being explored to eliminate highly invasive and chemoradioresistant glioblastoma (GBM) cells involved in rapid relapse. We recently showed that concomitant stereotactic injections of non-alloreactive allogeneic V gamma 9V delta 2 T lymphocytes eradicate zoledronate-primed human GBM cells. In the present study, we investigated the spontaneous reactivity of allogeneic human V gamma 9V delta 2 T lymphocytes toward primary human GBM cells, in vitro and in vivo, in the absence of any prior sensitization. Experimental Design: Through functional and transcriptomic analyses, we extensively characterized the immunoreactivity of human V gamma 9V delta 2 T lymphocytes against various primary GBM cultures directly derived from patient tumors. Results: We evidenced that GBM cells displaying a mesenchymal signature are spontaneously eliminated by allogeneic human V gamma 9V delta 2 T lymphocytes, a reactivity process being mediated by gamma delta T-cell receptor (TCR) and tightly regulated by cellular stress-associated NKG2D pathway. This led to the identification of highly reactive V gamma 9V delta 2 T lymphocyte populations, independently of a specific TCR repertoire signature. Moreover, we finally provide evidence of immunotherapeutic efficacy in vivo, in the absence of any prior tumor cell sensitization. Conclusions: By identifying pathways implicated in the selective natural recognition of mesenchymal GBM cell subtypes, accounting for 30% of primary diagnosed and 60% of recurrent GBM, our results pave the way for novel targeted cellular immunotherapies.