Monophosphoryl lipid A and Poly I:C combination adjuvant promoted ovalbumin-specific cell mediated immunity in mice model

Abstract

Induction of antigen-specific cell-mediated immunity (CMI) as well as humoral immunity is critical for successful vaccination against various type of pathogens. Toll-like receptor (TLR) agonists have been developed as adjuvants to promote vaccine efficacy and induce appropriate immune responses. Monophosphoryl lipid A (MPL); a TLR4 agonist, and polyinosinic acid: polycytidylic acid (Poly I:C); a TLR3 agonist, are known as a strong immuno-stimulator which induce Th1 response. Many studies proved and compared the efficacy of each adjuvant, but no study has investigated the combination of them. Using ovalbumin protein antigen, MPL+Poly I:C combination induced more effective CMI response than single adjuvants. Production of inflammatory cytokines and population of innate immune cells and CD4/CD8 memory T cell at the immunized site had been significantly enhanced by MPL+Poly I:C combination. Moreover, MPL+Poly I:C combination enhanced ovalbumin-specific serum IgG, IgG1 and IgG2c production and proliferative function of CD4 and CD8 T cell after in vitro ovalbumin peptide stimulation. Taken together, these data suggest that combination of MPL and Poly I:C has a potency as a CMI-inducing vaccine adjuvants with highly increased effects.