Enhanced Human Antigen‐Specific B Cell Responses Using In Vitro 3D Tonsil Cultures Containing Stromal Cells

Germinal centers (GCs) are specialized sites within secondary lymphoid organs where B cells expand, are selected, and mature to produce high-quality antibodies. Their structural complexity makes them difficult to model in vitro. Here, we developed a human 3D lymphoid culture system combining lymphoid and stromal cells to better mimic GC environments than conventional 2D cultures. Tonsil cells were cultured with or without fibroblastic reticular cells (FRCs) in 2D or 3D hydrogels and stimulated with viral antigens or vaccines. FRC-supported 3D cultures significantly improved B and T cell survival and promoted reaggregation into follicle-like structures with. 3D FRC-supported co-cultures higher levels of antigen-specific antibodies, increased frequencies of S- or HA-specific B cells, and enhanced differentiation into antibody-secreting cells. Importantly, these cultures also showed reduced cell death and lower bystander activation and CXCR4 and CXCR5 expression on CD27+CD38+ B cells indicated GC-like polarization. Autologous and allogeneic FRCs performed comparably, supporting the scalability of the model for high-throughput applications. This 3D platform offers a more physiologically relevant system for studying human GC-associated immune responses and may facilitate mechanistic research and screening of vaccine immunogens and adjuvants in a controlled laboratory setting.