PhD student Dartmouth College Wilder, Vermont, United States
Disclosure(s):
Maria Cavallaro, BSc: No financial relationships to disclose
Introduction/Rationale: B cells support anti-tumor immunity via antibody production, antigen presentation, and immunomodulation. Somatic hypermutation (SHM) diversifies receptors to recognize tumor antigens. The origin of tumor-infiltrating B cells (TIBs) is unclear: they may arise from germinal centers (GCs) in tumor-draining lymph nodes (tdLNs) or tertiary lymphoid structures (TLSs) within tumors. Understanding B cell migration between these sites, maturation differences, and transcriptional programs driving differentiation and affinity maturation is key to defining their anti-tumor role and improving immunotherapy and tumor resection strategies.
Methods: B cells from paired tumors and tdLNs of NSCLC patients treated with neoadjuvant PD-L1 blockade were isolated by flow cytometry and analyzed with single-cell RNA and BCR sequencing (10x Genomics). We profiled subtypes, class switching, SHM levels, and clonal lineages using the Immcantation pipeline. Transcriptional profiles assessed activation, effector functions, and maturation states.
Results: Shared B cell lineages across tumors and tdLNs suggest dynamic migration. Many lineage trees link antibody-secreting tumor cells to GC B cells in tdLNs, indicating maturation there before tumor infiltration. Tumor GC B cells show distinct transcriptional signatures and SHM levels, implying unique maturation stages. Clonal overlap between tumor and tdLNs varies by donor, reflecting personalized B cell responses.
Conclusion: Our findings reveal patient-specific B cell clonal diversity and migration between GCs in tdLNs and TLSs, highlighting anti-tumor B cell complexity. Mapping these trajectories clarifies sites of B cell maturation and functional adaptation, informing strategies to enhance anti-tumor responses, refine tumor resection, and optimize immunotherapy. Future studies adding spatial resolution will clarify B cell niches and tumor microenvironment interactions and link migratory patterns to tumor antigen affinity.
