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. 2020 Nov 24;11:594911. doi: 10.3389/fimmu.2020.594911

Figure 2.

Figure 2

An overview of the immune response after vaccination with an MCT® depot. (A) The early innate response is characterized by immediate exudation of neutrophils and eosinophils in vivo. The role of inflammasome/DAMP-associated mechanisms have not been precisely defined. The innate response has recorded an increase in dendritic cells (DCs), observed 24 h post-injection (45). MCT® is biodegradable/biocompatible with an estimated half-life of 48 h at the injection site (44). As a result, it is cleared within 7 days with a return to a local steady state. The biodegradable depot properties of MCT® are thought to be key in orchestrating the subsequent adaptive response. (B) The infiltrating antigen presenting cells to the draining lymph node, induce sustained and robust B cell response, via MHC class II antigen presentation (45, 52–44, 54), with sustained IgG antibody titers. The prolonged immune exposure of antigen is thought to further DC uptake and initiate CD4 T helper cell (Tfh) clonal expansion and differentiation (45). Furthermore, immune complexes may form with follicular dendritic cells (FDCs) via Fcγ receptors (Cd16 and CD32) and complement receptors (CD35). (C) The depot properties of MCT® have been shown to be key in generating a more robust cytotoxic T cell response, thus the priming of T cells combined with optimal antigen delivery, such as when combined with VLPs, are key drivers in orchestrating this arm of the adaptive response (50).