Figure 3.

Mechanism of action of nanovaccines.

Different types of antigens conjugated to nanoparticles (NPs) stimulate antigen-presenting cells (APCs) to process and present the antigens in different manners. Some antigens are received by mannose receptors, some are degraded within the APCs and the antigenic peptide fragments are then presented via MHC I (to activate CD8 T cells) or via MHCII (to activate CD4 T cells). APCs (like dendritic cells and T cells) also secrete cytokines in the process. This release of cytokines alters the cytokine milieu and shapes either pro- or anti-inflammatory responses. Clonal expansion of the activated T cells and B cells leads to boosting of the immune response. Activated plasma B cells release antibodies in response to the specific antigen conjugated to the NPs. Some cells remain as memory cells to provide an immediate antibody response in the case of natural antigenic challenge. The annotations adjacent to individual nanovaccines highlight mechanistic steps taking place in APCs or downstream immune response column and illustrate the diverse mechanisms of action of individual nanovaccines. Abbreviation: LPS, lipopolysaccharide.