Mastering Immunity: Antibody Feedback as a Driver of Germinal Center Fate and Vaccine Responses.

Antibody feedback in germinal center (GC) responses plays a key role in shaping the affinity, specificity, and longevity of humoral immunity. Beyond neutralizing pathogens, antibodies influence B cell selection by modulating antigen availability and masking dominant epitopes, thereby reshaping the competitive landscape for T follicular helper (Tfh) cell support. This review outlines the current understanding of how antibody feedback governs the selection stringency and clonal evolution of GC B cells, facilitates and promotes the emergence of epitope spread, and contributes to GC shutdown. We also examine how it supports the development of broadly neutralizing antibodies. Finally, we discuss how these insights are informing next-generation vaccine strategies-including immunogen design, prime-boost regimens, and adjuvant optimization-to guide affinity maturation toward specific epitopes and overcome feedback-driven constraints. Understanding antibody feedback not only reveals fundamental principles of adaptive immunity but also offers new avenues for rational vaccine design and therapeutic immune modulation.