Comparative Analysis of Extracellular Vesicles from Cytotoxic CD8+ αβ T Cells and γδ T Cells.

Background: Although belonging to different branches of the immune system, cytotoxic CD8⁺ αβ T cells and γδ T cells utilize common cytolytic effectors including FasL, granzymes, perforin and granulysin. The effector proteins are stored in different subsets of lysosome-related effector vesicles (LREVs) and released to the immunological synapse upon target cell encounter. Notably, in activated cells, LREVs and potentially other vesicles are continuously produced and released as extracellular vesicles (EVs). Presumably, EVs serve as mediators of intercellular communication in the local microenvironment or at distant sites.

Methods: EVs of activated and expanded cytotoxic CD8⁺ αβ T cells or γδ T cells were enriched from culture supernatants by differential and ultracentrifugation and characterized by nanoparticle tracking analyses and Western blotting. For a comparative proteomic profiling, EV preparations from both cell types were isobaric labeled with tandem mass tags (TMT10plex) and subjected to mass spectrometry analysis.

Results: 686 proteins were quantified in EV preparations of cytotoxic CD8⁺ αβ T cells and γδ T cells. Both populations shared a major set of similarly abundant proteins, while much fewer proteins presented higher abundance levels in either CD8⁺ αβ T cells or γδ T cells. To our knowledge, we provide the first comparative analysis of EVs from cytotoxic CD8⁺ αβ T cells and γδ T cells.