Sorted B cells from mice treated with MPL and/or R837

Many successful vaccines induce persistent antibody responses that can last a lifetime. The mechanisms by which they do so remain unclear, but emerging evidence suggests that activate dendritic cells (DCs) via Toll-like receptors (TLRs). For example, the yellow fever vaccine YF-17D, one of the most successful empiric vaccines ever developed, activates DCs via multiple TLRs to stimulate pro-inflammatory cytokines. Triggering specific combinations of TLRs in DCs can induce synergistic production of cytokines, which results in enhanced T cell responses, but its impact on antibody responses remain unknown. Learning the critical parameters of innate immunity that programs such antibody responses remains a major challenge in vaccinology. We demonstrated that immunization of mice with synthetic nanoparticles containing antigens plus Toll-like receptor (TLR) ligands 4 (MPL) + 7 (R837) induces synergistic increases in antigen-specific, neutralizing antibodies compared to immunization with a single TLR ligand. To determine whether there was any early programming of B cells, we isolated isotype switched, TCRbeta-CD11b-CD19+IgD-IgG+ B cells by FACS at 7 days post immunization with nanoparticles containing various adjuvants plus OVA, and performed microarray analyses to assess their molecular signatures.