A combination adjuvant of monophosphoryl lipid A and Poly I:C enhanced vaccine efficacy by functional natural killer cell activation and DC maturation

Abstract

The traditional vaccines were appeared to be concerned either safety or efficacy. Natural killer cells were demonstrated as an effective targeting immune cell used in immunotherapy and cancer therapy for several decades with their well-known ability to control tumor cell spread and microbial infections. Beside to their lysis capacity of target cells, NK cells were also defined as regulatory cells with immunoregulatory cytokine producing functions. Notably, most of markers expressing on NK cell can be triggered by Toll-like receptor-signaling pathways, resulting in utilization of Toll-like receptor agonists as a potential approach to stimulate NK activation. Herein, we studied the effects of monophosphoryl lipid A (MPL) and polyriboinosinic polyribocytidylic acid (Poly I:C) on NK cell cytotoxic and regulatory functions after intranasally immunization with Ovalbumin. The findings provided that individual Poly I:C was effective in recruitment and stimulation of NK cell expressing CD69 and CD107a activation markers at prime dose, and exhibiting highly cytolytic activity as well, but not that of boost dose and regulatory functions. The combination of MPL and Poly I:C, whereas, displayed a significantly efficacy not only in inducing NK activation release of cytokines, up-regulation of lyse ability and also in enhancement of collaboration with Dendritic cells (DCs) as compared to individual adjuvants or naïve mice. Taken together, these data suggest that combination adjuvant of MPL and Poly I:C might be a promised adjuvant in vaccination with a capacity to strongly enhance immune responses particularly NK cells, leading to improve vaccine efficacy.