Enhanced immune response induced by BSA loaded in hydroxyethylstarch microparticles

Microparticles and nanoparticles represent promising carriers for the in vivo delivery of peptides, proteins or deoxyribonucleic acid (DNA). In this study, new hydroxyethylstarch (HES) microparticles were obtained by interfacial cross-linking with terephtaloyl chloride. These microparticles exhibit the characteristics required to improve antigen release and presentation to antigen presentating cells compared to free antigens. The adjuvant activity of HES microparticles as vaccine carrier was investigated in mice using bovine serum albumin (BSA) as model antigen. We showed HES microparticles were phagocyted by peritoneal mononuclear cells. The immunization with BSA-microparticles induced antibody synthesis that was predominantly immunoglobulin G1 (IgG1). Aluminium hydroxide remained more efficient to induce IgG synthesis. The analysis of the cytokine profile from spleen cells revealed that BSA-microparticles induced the secretion of both interferon-γ (IFN-γ) and interleukin-4 (IL-4). However, the immune responses induced by BSA-microparticles were qualitatively and quantitatively affected by the route of injection. Taken together, these results demonstrate that HES microparticles induce a mixed T helper 1/T helper 2 response against BSA and may be a suitable delivery and presentation system in the field of vaccine development.