Fig. 3.

Recent developments in nanoparticle (NP) – mediated immunotherapy may target antigen-presenting cells (APCs) or the adaptive arm of immunity. Cell targeting ligands enable specific delivery to each cell type. To avoid non-specific uptake by the reticular endothelial system (RES), NPs may be conferred with stealth properties by modifying their surface with polyethylene glycol (PEG). Strategies of NP immunotherapy include boosting T cell effector function, M2-M1 reprogramming of macrophages, using immune cells as cellular chaperones of therapeutic cargo or NP-enhanced delivery of monotherapy or combination therapy. Stimuli (either external or by tumor environment conditions) may trigger NP release of therapeutic cargo. Interaction of NPs with immune cells depend on the NP's biological identity as defined by the protein corona, and its physicochemical properties.