Role of lipopolysaccharide in the induction of type I interferon-dependent cross-priming and IL-10 production in mice by meningococcal outer membrane vesicles.

We investigated the contribution of lipopolysaccharide (LPS) to adjuvant properties of native outer membrane vesicles (NOMV), a vaccine candidate for meningococcal B disease. NOMV induce the maturation of and cytokine production by murine bone marrow-derived dendritic cells through both toll-like receptors (TLR) 2 and 4 which are mostly dependent on the signalling adaptor MyD88. NOMV are also able to induce B cell proliferation in splenocytes from LPS-hyporesponsive mice. However, induction of IL-10 and type I interferon-dependent, antigen-specific and IFN(gamma)-secreting CD8(+) cytotoxic T lymphocyte responses in vivo by NOMV requires LPS. The importance of LPS in the induction of IL-10 and functional cross-priming has implications for NOMV-based vaccine and adjuvant development.