In Vivo Requirement for Atg5 in Antigen Presentation by Dendritic Cells

Lee, H. K. et al. Immunity. 32: 227-239 (2010)

Speaker: Shu-Sheng Chen (陳沭勝)                                     Time: 15:00~16:00, Apr. 21, 2010

Commentator: Dr. Huan-Yao Lei (黎煥耀博士)          Place: Room 601

Abstract:

Antigen presenting cells (APCs) present intracellular antigens through MHC class I (MHC I) molecules and extracellular antigens via MHC class II (MHC II) molecules¹. In addition, extracellular antigens can also be processed in the context of MHC I molecules via cross-presentation pathway in some APCs, such as dendritic cells (DCs) ¹. On the other hand, some studies indicate that intracellular antigens can be processed and presented on MHC II molecules². Some in vitro studies show that autophagy is involved in MHC II presentation of intracellular antigens, and this pathway results in enhanced CD4⁺ T cell priming². However, the contribution of autophagic delivery in antigen presentation and enhancement of CD4⁺ T cell priming in vivo remains unclear. In this study, the authors found that cell migration, upregulation of MHC II and costimulatory molecules, cytokine production, and endocytic or phagocytic capacity were not impaired in DCs from Atg5^-/- mice. In contrast, CD4⁺ T cell priming was impaired after herpes simplex virus infection in Atg5^-/- mice. Furthermore, Atg5 was required for optimal processing and antigen presentation by MHC II in DC via phagosome-to-lysosome fusion pathway. Taken together, autophagy facilitates antigen presentation for MHC II in dendritic cells.

References:

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2.      Lünemann JD and Münz C. Autophagy in CD4⁺ T cell immunity and tolerance. Cell Death Differ. 16: 79-86. (2009)