CD4 and nasopharyngeal carcinoma: Comprehensive single-cell RNA sequencing analysis of 16 EBV-positive NPC specimens and 8 normal nasopharyngeal controls (Fig. 7A) systematically characterized the tumor ecosystem, identifying major cellular subsets through lineage-specific markers: T lymphocytes (CD2/CD3/CD4/CD8), myeloid populations (CD14/CD68), B lymphocytes (CD79/MS4A1), plasmacytoid dendritic cells (CXCR3/IL3RA), fibroblasts (COL1A1/COL1A2), vascular endothelial cells (VWF/PECAM1), and epithelial compartments (EPCAM/KRT19) (Fig. 7B).