# Small Messengers: Glioblastoma-Derived Extracellular Vesicles Modulate γδ T Lymphocytes Through a MIC-Dependent Mechanism

## TL;DR

This study shows that glioblastoma-derived extracellular vesicles can activate γδ T cells through MICA/B proteins, potentially improving immune-based treatments for brain cancer.

## Contribution

The study identifies a MIC-dependent mechanism by which glioblastoma-derived EVs modulate γδ T lymphocytes, offering new insights for immunotherapy.

## Key findings

- Glioblastoma-derived EVs increase γδ T cell activation and production of TNF-α and IFN-γ.
- EV-induced γδ T cell activation is reduced when MICA/B proteins are blocked.
- EVs enhance γδ T cell cytotoxicity against tumor cells via a MIC-dependent mechanism.

## Abstract

Glioblastoma is an aggressive brain tumor that evades the immune system; this study asked whether tiny particles released by glioblastoma cells (extracellular vesicles, or EVs) can influence a specific type of immune cell called a γδ T lymphocyte. For that purpose, we first characterize EVs from the U251 glioblastoma cell line and test whether they bind to, enter, and activate γδ T cells, and which molecules on EVs drive that effect. We found that the isolated EVs were enriched in medium/large sizes, contained tumor markers including EGFR and the stress ligands MICA/B, and were taken up by γδ T cells. Exposure to these EVs increased an early activation marker (CD69), raised production of inflammatory proteins TNF-α and IFN-γ, and enhanced the T cells’ ability to kill tumor cells. Blocking MICA/B on EVs reduced activation. These results suggest U251-derived EVs can stimulate antitumor γδ T-cell responses via MICA/B, offering a potential avenue to boost immune therapies and improve outcomes for patients.

Glioblastoma (GBM) is the most aggressive and common primary brain tumor, with a median survival of less than a year after diagnosis. γδ T lymphocytes are immune cells that can migrate to tumors and induce malignant cells’ apoptosis. Our previous in silico studies showed that higher γδ T-cell infiltration in GBM correlates with better patient survival, and in vitro experiments showed that GMB supernatants promote an antitumoral profile in γδ T cells. Extracellular vesicles (EVs) play a critical role in cell communication, particularly in tumor microenvironment modulation. Here, we studied the mechanisms responsible for γδ T lymphocyte activation by GBM-derived EVs, together with the effect of these EVs on γδ T cells from GBM patients. For that, γδ T cells were purified from peripheral blood, and EVs were obtained from U251 cell supernatants by differential centrifugation. After EV characterization, we evaluated the γδ T cell–EV interaction and γδ T-cell modulation by EVs. Results showed that EVs induced an increase in CD69 expression, cytotoxicity, and TNF-α and IFN-γ production in γδ T cells in a MIC-dependent mechanism. These results provide valuable insights for developing targeted immunotherapies in GBM patients.