Comparison of the adjuvanticity of two different delivery systems on the induction of humoral and cellular responses to synthetic peptides

The aim of this work was to test, evaluate, and compare the immunogenicity of the S3 malarial short synthetic model peptide in Balb/c mice when it was delivered with different adjuvants. Specifically, it studied the adjuvanticity of two different particulate delivery systems, human compatible Montanide (R) ISA 720 w/o emulsion and poly-lactide-co-glycolide acid microparticles, in terms of the enhancement and sub-set type of the immune response elicited following immunization. Aditionally, conventional aluminum hydroxide gel adjuvant was included as a reference. Aluminum adjuvant failed to improve the lack of immunogenicity of this antigenic peptide on its own. On the other hand, Montanide and microparticles given subcutaneously resulted in effective adjuvants and revealed mixed Th1/Th2 immune responses, with moderate antibody and lymphoproliferative responses, and higher IFN-gamma secretion for Montanide. Hence, microparticles administered intradermally (not possible with Montanide) elicited superior and potent antibody levels, including higher cytophilic isotype (IgG2a), and the greatest limphoproliferation and IFN-gamma levels. The results here presented support the capability and suitability of microparticle delivery systems to reach the adequate adjuvanticity necessary for future malaria vaccine development.