Activation of dendritic cells by soypeptide lunasin as a novel vaccine adjuvant (VAC6P.942)

Abstract

Abstract Adjuvants enhance the immunogenicity of vaccines and improve the immune responses. FDA approved aluminum is known to promote Th2 immune response, which is the most used adjuvant in human vaccines; however it is less efficient on eliciting cellular immune responses. Thus, any agent capable of modulating the immune responses is the key to develop efficacious vaccines. We have identified a new use of soypeptide lunasin as a novel immune modulator. The objective is to define the effectiveness of lunasin as an adjuvant on activating immune responses. Human peripheral blood mononuclear cells of normal donors were stimulated with various concentrations of lunasin followed by phenotypic analysis of DC subsets. Lunasin-treated conventional DCs (cDCs) not only expressed elevated co-stimulatory molecules (CD86) but up-regulated chemokines (CCL2, CCL3, CCL4) and cytokine (IL-1β). Lunasin-treated cDCs induced higher proliferation of allogeneic CD4+ T cells when comparing with medium control treatment in mixed lymphocyte reaction. In addition to cDCs, pDCs responded to lunasin stimulation as evidenced by IFNa production. Lunasin administration increased CD86 expression in cDCs and induced IFNa production by pDCs in mice. Moreover, immunization with OVA and lunasin in mice improved survival against OVA-expressing influenza virus. Our data suggest that lunasin may act as an adjuvant by targeting both cDCs and pDCs to enhance and modulate immune responses to vaccine antigens.