Vaccine adjuvant ARNAX promotes mucosal IgA production in influenza HA vaccination.

Adjuvant stimulates pattern-recognition receptors (PRRs) expressed by dendritic cells, which causes immune-enhancing of T lymphocytes. Adjuvant also induces innate immune response in whole-body cells via PRRs to evoke cytokinemia. A cytokine-mediated immune response is important for the systemic protection of a host from microbial infections. Using an influenza subcomponent vaccine in a mouse model, we intranasally administered a TLR3-specific adjuvant ARNAX + HA split vaccine to mice. ARNAX efficiently induced mucosal IgA and systemic IgG production by nasal drop. Moreover, ARNAX + HA simultaneously induced CD8 and CD4 T cell activation. We have previously shown that ARNAX does not induce harmful systemic cytokine production. Thus, our findings indicate that the ARNAX + HA vaccine is a harmless prophylactic vaccine for flu that induces HA-specific T cell activation and IgA/IgG production. These results suggested that ARNAX + antigen enhanced the immune response without inducing inflammatory toxicity for vaccination against infectious diseases.