AUTHOR=Compeer Ewoud B., Flinsenberg Thijs W., van der Grein Susanna G., Boes Marianne TITLE=Antigen Processing and Remodeling of the Endosomal Pathway: Requirements for Antigen Cross-Presentation JOURNAL=Frontiers in Immunology VOLUME=Volume 3 - 2012 YEAR=2012 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2012.00037 DOI=10.3389/fimmu.2012.00037 ISSN=1664-3224 ABSTRACT=The cross-presentation of endocytosed antigen as peptide/class I MHC 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 (APC) capable of antigen cross-presentation, description 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 highlight DC-intrinsic mechanisms that facilitate the cross-presentation of endocytosed antigen, including receptor-mediated uptake, recycling and maturation including the sorting of membrane proteins, dynamic remodeling of endosomal structures and cell-surface directed endosomal trafficking. We will conclude with description of pathogen-induced deviation of endosomal processing, and discuss how immune evasion strategies pertaining endosomal trafficking may preclude antigen cross-presentation.