Narasimhan et al. (2016). Journal of Biomedical Nanotechnology. doi: 10.1166/jbn.2016.2242
…stained with combina- tions of fluorochrome-conjugated antibodies to identify various cell subsets. Non-specific binding of conjugated antibodies was inhibited by blocking cells with 10 L of rat serum (Pel Freez, Rogers, AR) and 10 g of 2.4G2, an anti-FcR monoclonal antibody. Rat anti-mouse mon- oclonal antibodies used were anti-IgM (b7-6), anti-B220 (6B2), anti-CD44 (9F3), anti-CD4 (PerCP/Cy5.5 conju- gate,…
Abstract
Biodegradable polymeric nanoparticle-based subunit vaccines have shown promising characteristics by enhancing antigen presentation and inducing protective immune responses when compared with soluble protein. Specifically, polyanhydride nanoparticle-based vaccines (i.e., nanovaccines) have been shown to successfully encapsulate and release antigens, activate B and T cells, and induce both antibody- and cell-mediated immunity towards a variety of immunogens. One of the characteristics of strong thymus-dependent antibody responses is the formation of germinal centers (GC) and the generation of GC B cells, which is part of the T helper cell driven cellular response. In order to further understand the role of nanovaccines in the induction of antigen-specific immune responses, their ability to induce germinal center B cell formation and isotype switching and the effects thereof on serum antibody responses were investigated in these studies. Polyanhydride nanovaccines based on 1,6-bis(p-carboxyphenoxy)hexane and 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane were used to subcutaneously administer a viral antigen. GC B cell formation and serum antibody responses induced by the nanovaccines were compared to that induced by alum-based vaccine formulations. It was demonstrated that a single dose of polyanhydride nanovaccines resulted in the formation of robust GCs and serum antibody in comparison to that induced by the alum-based formulation. This was attributed to the sustained release of antigen provided by the nanovaccines. When administered in a multiple dose regimen, the highest post-immunization titer and GC B cell number was enhanced, and the immune response induced by the nanovaccines was further sustained. These studies provide foundational information on the mechanism of action of polyanhydride nanovaccines.