Cross-presentation of phage particle antigen in MHC class II and endoplasmic reticulum marker-positive compartments
✍ Scribed by Ying Wan; Yuzhang Wu; Jingran Zhou; Liyun Zou; Yunfei Liang; Jianping Zhao; Zhengcai Jia; Jan Engberg; Jiang Bian; Wei Zhou
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 609 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0014-2980
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✦ Synopsis
It has been shown that exogenous antigens can access the MHC class I pathway of professional antigen-processing cells. However, details as to how the MHC class I-peptide complex forms in the presentation pathway are still poorly understood. Here we used MHC class I-peptide-specific antibodies to investigate the formation and intracellular location of class I-peptide complexes in macrophages. We observed that the formation of class I-peptide complexes occurs within a few hours and lasts for another few hours on the cell surface of macrophages following loading with filamentous phage particles. The class I-peptide complexes in the process were co-localized with MHC class II molecules and endocytic system markers. Moreover, endosomal compartments containing class I-peptide complexes were found within intracellular organelles stained by DiOC6 and calnexin. In addition, the cross-presentation of phage particles was transporter associated with antigen processing (TAP)-dependent and sensitive to proteasome inhibitors and NH(4)Cl. These data suggest that endocytosed phage particles may be processed and cross-presented in organelles positive for phagosome and endoplasmic reticulum (ER) markers via a classical ER MHC class I loading mechanism.