Comparative activity of biodegradable nanoparticles with aluminum adjuvants: antigen uptake by dendritic cells and induction of immune response in mice.

Biodegradable poly(γ-glutamic acid) (γ-PGA) nanoparticles (NPs) are considered to be an excellent antigen carrier. Antigen-carrying γ-PGA NPs were examined for their uptake by murine dendritic cells (DCs) and subsequent induction of antigen-specific immune responses in mice and compared with aluminum (AL) adjuvants. Ovalbumin (OVA)-carrying NPs (FITC-OVA-NPs) were taken up much more efficiently by DCs than OVA alone or its AL-associated form. Both OVA-NPs and OVA+AL were detected in an intracellular lysosome compartment of DCs. Furthermore, the uptake of γ-PGA NPs was inhibited in the presence of pinocytosis and phagocytosis inhibitors. Significantly higher induction of antigen-specific CD8(+) T cells was observed in mice immunized with OVA-carrying γ-PGA NPs than in those immunized with OVA alone, OVA+AL, OVA+3-O-desacyl-4'-monophosphoryl lipid A (MPL), and OVA+AL+MPL. Thus, γ-PGA NPs may have great potential as an effective vaccine carrier and adjuvant for clinical use.