RESUMO
Influenza viruses escape immunity owing to rapid antigenic evolution, which requires vaccination strategies that allow for broadly protective antibody responses. We found that the lipid globotriaosylceramide (Gb3) expressed on germinal center (GC) B cells is essential for the production of high-affinity antibodies. Mechanistically, Gb3 bound and disengaged CD19 from its chaperone CD81, permitting CD19 to translocate to the B cell receptor complex to trigger signaling. Moreover, Gb3 regulated major histocompatibility complex class II expression to increase diversity of T follicular helper and GC B cells reactive with subdominant epitopes. In influenza infection, elevating Gb3, either endogenously or exogenously, promoted broadly reactive antibody responses and cross-protection. These data demonstrate that Gb3 determines the affinity and breadth of B cell immunity and has potential as a vaccine adjuvant.
Assuntos
Anticorpos Antivirais , Linfócitos B , Centro Germinativo , Infecções por Orthomyxoviridae , Orthomyxoviridae , Triexosilceramidas , Formação de Anticorpos , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Centro Germinativo/efeitos dos fármacos , Centro Germinativo/imunologia , Triexosilceramidas/metabolismo , Triexosilceramidas/farmacologia , Animais , Camundongos , Camundongos Knockout , Humanos , Orthomyxoviridae/imunologia , Infecções por Orthomyxoviridae/imunologia , Anticorpos Antivirais/biossíntese , Anticorpos Antivirais/imunologiaRESUMO
Influenza viruses escape immunity due to rapid antigenic evolution, which requires vaccination strategies that allow for broadly protective antibody responses. Here, we demonstrate that the lipid globotriaosylceramide (Gb3) expressed on germinal center (GC) B cells is essential for the production of high-affinity antibodies. Mechanistically, Gb3 binds and disengages CD19 from its chaperone CD81 for subsequent translocation to the B cell receptor (BCR) complex to trigger signaling. Abundance of Gb3 amplifies the PI3-kinase/Akt/Foxo1 pathway to drive affinity maturation. Moreover, this lipid regulates MHC-II expression to increase diversity of T follicular helper (Tfh) and GC B cells reactive with subdominant epitopes. In influenza infection, Gb3 promotes broadly reactive antibody responses and cross-protection. Thus, we show that Gb3 determines affinity as well as breadth in B cell immunity and propose this lipid as novel vaccine adjuvant against viral infection. One Sentence Summary: Gb3 abundance on GC B cells selects antibodies with high affinity and broad epitope reactivities, which are cross-protective against heterologous influenza infection.