CD4 and neoplasm: In esophageal squamous carcinoma, mature TLS exhibit a heightened presence of CD8+ T cells compared to immature TLS, yet a concurrent reduction in the expression of MHC class I molecules within mature TLS is accompanied by an increase in CD4+ Th17 cells, suggesting that Th17 cells may augment CD8+ T-cell immunity beyond the confines of TLS within tumor tissues (33, 127).