Adjuvant Effect Of Type I Interferon Induced By Many But Not All Commercial Influenza Vaccines

Background: Seasonal influenza vaccines approved and offered in the United States have varying reported degrees of effectiveness year over year and between manufacturers. Influenza vaccines produced from live virus may include single stranded RNA (ssRNA) that is a potent activator of the innate Toll-like receptor 7 (TLR-7) ligand. Plasmacytoid dendritic cells (pDC) can be activated by ssRNA to produce type I interferons such as IFN-alpha, which has been shown to have an adjuvant-like effect.Objective: Our aim was to determine if IFN-alpha induction in peripheral blood mononuclear cells (PBMCs) exposed to eight different commercial influenza vaccines is a pDC-dependent process mediated through TLR-7 signaling.Results: We demonstrate the ability of multiple vaccines to induce IFN-alpha in a TLR-7-dependent fashion. A number of vaccines however lacked IFN-alpha induction. The significance of these differences between vaccines is unclear, since all the approved vaccine formulations offer some degree of protection. Published by Elsevier Ltd.