T‐Cell‐Derived Exosomes From Multi Core Granules Exhibit Superior Caspase‐3‐Mediated Tumor‐Suppressive Activity Compared to Those From Multivesicular Bodies

Journal article

Small extracellular vesicles (sEVs) derived from cytotoxic T lymphocytes (CTLs) are emerging as potential mediators of antitumor immunity; however, their subcellular origins and functional properties remain incompletely defined. In this study, we investigated the intracellular routes and cytotoxic potential of CTL‐derived exosomes. Using correlative light and electron microscopy, we discovered that CTL‐derived exosomes originate from both classical multivesicular bodies (MVBs) and the recently identified multi core granules (MCGs). Through total internal reflection fluorescence microscopy, we demonstrated that, in contrast to MVB‐derived exosomes, MCG‐derived exosomes are released at the immunological synapse in a stimulus‐dependent manner. To enable functional characterization, we developed a scalable primary cell culture method for the isolation of high‐purity exosomes. Super‐resolution microscopy revealed significant heterogeneity in exosome size and tetraspanin composition. Notably, MCG‐derived exosomes exhibited fivefold higher cytotoxic activity than MVB‐derived exosomes, inducing apoptosis in tumor cells via a caspase 3‐dependent mechanism. These findings reveal that CTLs exploit distinct secretory pathways to release heterogeneous exosome populations with differential cytotoxic capacities, offering new insights into CTL‐mediated immune responses and providing a basis for the development of novel exosome‐based immunotherapies.

Authors: Alawar, N; Schirra, C; Rasuli, R; Fecher‐Trost, C; Weins, L

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Journal of Extracellular Vesicles
• Volume: 15
• Issue: 2
• Article number: e70239
• Publication date: 2026-02-19
• Acceptance date: 2026-01-27
• DOI: 10.1002/jev2.70239
• EISSN: 2001-3078
• ISSN: 2001-3078
• Language: English
• Keywords: multivesicular bodies; Munc13‐4; tetraspanins; immunological synapse; primary cells; extracellular vesicles; CD8+ T‐cells; 10X‐expansion