Effects of Tumor-derived Exosomes (TEX) of Head and Neck cancer (HNSCC) patients on cytotoxic T cells

Background:

HNSCC-patients often incur profound immunosuppression. exosomes have been shown to play an important role in said immunosuppression, especially via PDL1 interaction with immune cells. As of today, only the total exosomes or the CD3+ fraction was considered. Here, we show that the effects of TEX enriched with CD45neg selection differ between patients with high and low stage HNSCC.

Methods:

Exosomes were isolated from plasma of 20 HNSCC patients by mini size exclusion chromatography. TEX were captured by on bead-immunocapture using a biotinylated CD45 antibody. We measured the protein concentration of the CD45neg fraction. All fractions including the total fraction were incubated with activated human CD8+ T cells. Apoptosis of these T cells was measured by flow cytometry.

Results:

The protein concentration of the CD45neg TEX enriched fraction correlated with the tumor stage of the HNSCC patients: exosomes of high stage HNSCC patients displayed a higher protein concentration than exosomes of low stage patients. Additionally we observed a correlation between tumor stage and induction of apoptosis: exosomes of high stage HNSCC patients induced more apoptosis than exosomes of low stage patients. Interestingly, total exosome fraction induced less apoptosis than the CD45neg TEX enriched fraction.

Conclusion:

It could be shown that the enrichment of exosomes with CD45neg selection and subsequent quantification correlated with clinicopathological data in HNSCC patients. With this CD45neg selection we were able to enrich TEX with strong immunosuppressive properties and further characterize these.

Publikationsverlauf

Publikationsdatum:
23. April 2019 (online)