Tertiary lymphoid structures correlate with enhancement of antitumor immunity in esophageal squamous cell carcinoma.

BACKGROUND: Tertiary lymphoid structures (TLSs) are associated with a favorable prognosis in several cancers. However, the correlation between TLSs and outcomes of esophageal squamous cell carcinoma (ESCC) and the impact of TLSs on the tumor immune microenvironment (TIME) remain unknown. METHODS: We pathologically evaluated the significance of TLSs in ESCC focusing on TLS maturation using 180 ESCC specimens and performed single-cell RNA sequencing (scRNA-seq) using 14 ESCC tissues to investigate functional differences of immune cells according to TLS presence. RESULTS: TLS+ cases had better recurrence-free-survival (RFS) (p < 0.0001) and overall survival (OS) (p = 0.0016) compared with TLS- cases. Additionally, mature TLS+ cases had better RFS and OS compared with immature TLS+ cases (p = 0.019 and p = 0.015) and TLS- cases (p < 0.0001 and p = 0.0002). The scRNA-seq showed that CD8+ T cells in TLS+ tumors expressed high levels of cytotoxic signatures and antigen-presentation of dendritic cells (DCs) was enhanced in TLS+ tumors. Immunohistochemistry showed that the densities of tumor-infiltrating CD8+ T cells and DCs were significantly higher in TLS+ tumors than those in TLS- tumors. CONCLUSIONS: These data suggest the prognostic and functional significance of TLSs in ESCC and provides new insights into TLSs on the TIME.