CD4 and nasopharyngeal carcinoma: To evaluate whether NPC exosomes play a role in the T-cell differentiation mediated by NPC cells, we assayed the frequency of IFNγ- and IL-17-producing T cells and FOXP3+ Tregs in the CD4+ T-cell population by FACS after coculture with TW03 (EBV+) cells and EXO1 or EXO2 in IL-2 medium for 7 days in vitro.