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Antigen loading of MHC class I molecules in the endocytic tract.
- Source :
-
Traffic (Copenhagen, Denmark) [Traffic] 2001 Feb; Vol. 2 (2), pp. 124-37. - Publication Year :
- 2001
-
Abstract
- Major histocompatibility complex (MHC) class I molecules bind antigenic peptides that are translocated from the cytosol into the endoplasmic reticulum by the transporter associated with antigen processing. MHC class I loading independent of this transporter also exists and involves peptides derived from exogenously acquired antigens. Thus far, a detailed characterization of the intracellular compartments involved in this pathway is lacking. In the present study, we have used the model system in which peptides derived from measles virus protein F are presented to cytotoxic T cells by B-lymphoblastoid cells that lack the peptide transporter. Inhibition of T cell activation by the lysosomotropic drug ammoniumchloride indicated that endocytic compartments were involved in the class I presentation of this antigen. Using immunoelectron microscopy, we demonstrate that class I molecules and virus protein F co-localized in multivesicular endosomes and lysosomes. Surprisingly, these compartments expressed high levels of class II molecules, and further characterization identified them as MHC class II compartments. In addition, we show that class I molecules co-localized with class II molecules on purified exosomes, the internal vesicles of multivesicular endosomes that are secreted upon fusion of these endosomes with the plasma membrane. Finally, dendritic cells, crucial for the induction of primary immune responses, also displayed class I in endosomes and on exosomes.
- Subjects :
- ATP Binding Cassette Transporter, Subfamily B, Member 2
ATP-Binding Cassette Transporters metabolism
Ammonium Chloride pharmacology
B-Lymphocytes immunology
B-Lymphocytes ultrastructure
Dendritic Cells metabolism
Dendritic Cells ultrastructure
Endosomes metabolism
Endosomes ultrastructure
Exocytosis
Histocompatibility Antigens Class I immunology
Histocompatibility Antigens Class II immunology
Histocompatibility Antigens Class II metabolism
Humans
Immunoblotting
Measles virus
Protein Transport
T-Lymphocytes, Cytotoxic drug effects
Viral Fusion Proteins metabolism
Antigen Presentation
Endocytosis physiology
Histocompatibility Antigens Class I metabolism
T-Lymphocytes, Cytotoxic immunology
Viral Fusion Proteins immunology
Subjects
Details
- Language :
- English
- ISSN :
- 1398-9219
- Volume :
- 2
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Traffic (Copenhagen, Denmark)
- Publication Type :
- Academic Journal
- Accession number :
- 11247303
- Full Text :
- https://doi.org/10.1034/j.1600-0854.2001.020207.x