Fig. 5.

Characteristics of exosomes fractionated from plasma of normal control (NC) or head and neck squamous cell carcinoma (HNSCC) patients. (a) Western blots of isolated exosomes demonstrating the presence of CD39 and CD73. CD81 is a tetraspanin used as an exosome marker. Note that exosomes obtained from HNSCC patients' plasma carry higher levels of both ectoenzymes than those obtained from NCs' plasma. (b) 5′-AMP and adenosine (ADO) production by isolated CD39⁺CD73⁺ exosomes (10ug protein) incubated with exogenous adenosine triphosphate (eATP) (20 μm). Exosomes produced more 5′-AMP and ADO than B cells or CD4⁺CD39⁺ T_reg (25 000 cells/well). Representative data from three experiments performed with exosomes and cells of different NC. (c) Box-plots show levels of 5′-AMP and ADO produced by exosomes obtained from NC (n = 6) or patients with HNSCC (n = 6). B cells (25 000/well) were used as a positive control. Cells were incubated in the presence of eATP (20uM) for 60 min. The baseline values are for exosomes incubated in the absence of ATP.