T-cell derived exosomes released from Multi-Core Granules exhibit potent caspase 3 mediated tumor suppressive activity ( Part II)

ABSTRACT: Small extracellular vesicles (sEV) derived from cytotoxic T lymphocytes (CTLs) are emerging as potential mediators of antitumor immunity, yet their subcellular origins and functional properties remain incompletely defined. In this study, we investigated the intracellular routes and cytotoxic potential of CTL-derived sEVs. Using correlative light and electron microscopy, we discovered that CTL-derived sEVs are exosomes, as they originate from both the classical multivesicular bodies (MVBs) and the recently identified multicore granules (MCGs). Applying total internal reflection fluorescence microscopy, we revealed 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 demonstrated significant heterogeneity in exosome size and tetraspanin composition. Notably, MCG-derived exosomes demonstrated five times 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

INSTRUMENT(S):

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): T Cell, Cytotoxic T-lymphocyte

SUBMITTER: Claudia Fecher-Trost  

LAB HEAD: Ute Becherer

PROVIDER: PXD070419 | Pride | 2026-02-23

REPOSITORIES: Pride