
pmid: 15894275
Extracellular antigens are internalized and processed before binding MHC class II molecules within endosomal and lysosomal compartments of professional antigen presenting cells (APC) for subsequent presentation to T cells. Yet select cytoplasmic peptides derived from autoantigens also intersect and bind class II molecules via an unknown mechanism. In human B lymphoblasts, inhibition of the peptide transporter associated with antigen processing (TAP) failed to alter class II-restricted cytoplasmic epitope presentation. By contrast, decreased display of cytoplasmic epitopes via class II molecules was observed in cells with diminished expression of the lysosome-associated membrane protein-2 (Lamp-2). Overexpression of Lamp-2 isoform A (Lamp-2a), an established component of chaperone-mediated autophagy, enhanced cytoplasmic autoantigen presentation. Manipulating APC expression of heat shock cognate protein 70 (hsc70), a cofactor for Lamp-2a, also altered cytoplasmic class II peptide presentation. These results demonstrate a novel role for the lysosomal Lamp-2a-hsc70 complex in promoting immunological recognition and antigen presentation.
Antigen Presentation, Cytoplasm, Glutamate Decarboxylase, Immunology, Histocompatibility Antigens Class I, HSC70 Heat-Shock Proteins, Histocompatibility Antigens Class II, Endosomes, In Vitro Techniques, Transfection, Lysosomal Membrane Proteins, Peptide Fragments, Recombinant Proteins, Cell Line, Infectious Diseases, Electroporation, Antigens, CD, Immunology and Allergy, Humans, ATP-Binding Cassette Transporters, HSP70 Heat-Shock Proteins, Lysosomes
Antigen Presentation, Cytoplasm, Glutamate Decarboxylase, Immunology, Histocompatibility Antigens Class I, HSC70 Heat-Shock Proteins, Histocompatibility Antigens Class II, Endosomes, In Vitro Techniques, Transfection, Lysosomal Membrane Proteins, Peptide Fragments, Recombinant Proteins, Cell Line, Infectious Diseases, Electroporation, Antigens, CD, Immunology and Allergy, Humans, ATP-Binding Cassette Transporters, HSP70 Heat-Shock Proteins, Lysosomes
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