CD274 and neoplasm: In GC models, increased MC density correlates with enhanced TNF-α/NF-κB-mediated PD-L1 expression in the tumor microenvironment and diminished CD8+ T-cell infiltration, creating an immune-suppressive niche that limits cytotoxic T-cell responses and facilitates immune escape in Hp-exposed esophageal epithelium and promoting tumor growth [106,110].