Fig. 1

Pathways of antigen recognition, processing, and presentation of DCs. a Antigen recognition and internalization into the early endosome through specific phagocytosis (microautophagy and chaperone-mediated autophagy) or non-specific macropinocytosis. b Dimers of MHC-I and MHC-II are formed in the endoplasmic reticulum (ER). MHC-II binds with a non-polymorphic invariant chain Ii (CD 74). c Gradual acidification to approximate pH 3.8–5.0 by the ATP-dependent vacuolar proton pump, increasing the lysosomal enzyme activity in the late endosomal and lysosomal-processing compartments. After proteolytic cleavage, antigens are transferred to MHC molecules. d MHC-I antigen cross-presentation involved in modulating receptor-mediated signaling. e MHC-II antigen presentation involved in modulating receptor-mediated signaling