biostudies-otherUnknownHomo sapiens (human)https://www.ebi.ac.uk/biostudies/studies/S-BSST1643biostudies-otherfalseTertiary lymphoid structures in pancreatic cancer resemble lymphoid follicles in secondary lymphoid organs as common sites of anti-tumor adaptive immune responsesTertiary lymphoid structures (TLS) in cancer are considered ectopic hotspots for immune activation, which are similar to lymphoid follicles in secondary lymphoid organs (SLO). This study elucidates shared and TLS/SLO-specific features in pancreatic ductal adenocarcinoma (PDAC). TLS abundance was related to superior survival and T-cell abundance in 110 treatment-naïve PDAC samples, underlining their clinical relevance. Immunofluorescence microscopy identified structural homologies between TLS and SLO. In RNA-expression analyses of laser-microdissected TLS and paired SLOs, we observed largely overlapping expression patterns of immune-related gene clusters, but distinct expression patterns of T-cell and complement-associated genes. Immune cells in TLS expressed essential markers of germinal center formation. Increased activation of tumor-draining lymph nodes in TLS-high patients highlights the relevance of these tumor-related structures to systemic immune response. We identified an overlap of expanded clonotypes in TLS and SLO in B-cell receptor sequencing as an additional correlate of systemic effects of TLS.2025-12-30T00:00:00Z2025-12-30T02:02:04.086Z2024-09-16T12:04:18.622ZS-BSST1643