Neisseria meningitidis PorB, a TLR2 ligand, induces an antigen-specific eosinophil recall response: potential adjuvant for helminth vaccines?

Efficacious adjuvants are important components of new vaccines. The neisserial outer membrane protein, PorB, is a TLR2 ligand with unique adjuvant activity. We demonstrate that PorB promotes Th2-skewed cellular immune response to the model Ag, OVA, in mice, including Ag-specific recall eosinophil recruitment to the peritoneum. PorB induces chemokine secretion by myeloid cells using both TLR2-dependent and -independent mechanisms, suggesting that anatomical distribution of TLR2(+) cells may not be a limiting factor for potential vaccine strategies. The results from this study suggest that PorB, and other TLR2 ligands, may be ideal for use against pathogens where eosinophilia may be protective, such as parasitic helminths.