Fig. 1

Biological processing of vaccines containing ABAs following intramuscular injection. 1. Vaccine preparation includes antigen adsorbed on the surface of the ABA, occluded within aggregates of ABA and, potentially, free antigen. 2. Biological fate of vaccine constituents includes; independent translocation of antigen (< ca 200 nm) to lymph nodes (2a); inflammatory monocyte/macrophage uptake of larger antigens through micropinocytosis (2c); intracellular antigens are either processed by the lysosomal system (L) or evade lysosomal capture through rupture of the endosome (2e); antigen associated with ABA (adsorbed or occluded) is internalised by phagocytosis (2b) and processed via autophagy, endosomes maturing into autophagosomes and ultimately, autolysosomes (AL) (2d). The biological mechanisms involved in the processing of these various entities contribute to the downstream activation of complexes such as the NALP-3 inflammasome and the subsequent release of pro-inflammatory cytokines including IL-1β