CTLA4 and nasopharyngeal carcinoma: The abundance of major cell lineages in EBV- NPC patients, does not significantly differ from the abundance in the EBV+ microenvironment, but the exhausted and immunoregulatory subtypes, such as HAVCR2+/PD-1+ T cells, CD25+/FOXP3+/CTLA4+ regulatory T cells (Tregs) and CD68+ myeloid-derived cells are found more enriched in the EBV+ microenvironment (11, 28).