Antigen processing and remodeling of the endosomal pathway: Requirements for antigen cross-presentation

Abstract

Cross-presentation of endocytosed antigen as peptide/class I major histocompatibility com- plex complexes plays a central role in the elicitation of CD8+ T cell clones that mediate anti-viral and anti-tumor immune responses. While it has been clear that there are specific subsets of professional antigen presenting cells capable of antigen cross-presentation, identification of mechanisms involved is still ongoing. Especially amongst dendritic cells (DC), there are specialized subsets that are highly proficient at antigen cross-presentation. We here present a focused survey on the cell biological processes in the endosomal pathway that support antigen cross-presentation.This review highlights DC-intrinsic mechanisms that facilitate the cross-presentation of endocytosed antigen, including receptor- mediated uptake, maturation-induced endosomal sorting of membrane proteins, dynamic remodeling of endosomal structures and cell surface-directed endosomal trafficking. We will conclude with the description of pathogen-induced deviation of endosomal processing, and discuss how immune evasion strategies pertaining endosomal trafficking may preclude antigen cross-presentation. © 2012 Compeer, Flinsen-berg, van der Grein and Boes.