Generation of both MHC class I- and class II-restricted antigenic peptides from exogenously added ovalbumin in murine phagosomes.
The phagosome fraction derived from a murine macrophage cell line (J774.1), which had internalized ovalbumin (OVA)-coated latex beads, was isolated. The peptides recovered from the phagosome fraction were separated on reverse phase HPLC and each fraction was analyzed for the content of either major histocompatibility complex (MHC) class I- or class II-restricted OVA-derived peptide. Both peptides were detected in the phagosome fraction after less than 15 min of internalization. It was also indicated that phagosomes degrade OVA protein into both MHC class I- and class II-restricted antigenic peptides by employing the same types of cathepsins. Furthermore, the results suggest that the MHC class I-restricted peptide rapidly exits from the phagosome to the cytosol. These findings illustrate a potential role for phagosomes not only in MHC class II-restricted but also in MHC class I-restricted exogenous antigen presentation pathways. Our results also point to the vital role of phagosomes in non-cytosolic antigen presentation pathway, in which further degradation of antigens by the proteasome is dispensable.
Muno
D
D
Department of Biochemistry, School of Medicine Juntendo University, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan.
Kominami
E
E
Mizuochi
T
T
D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D007700:Kinetics; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008863:Microspheres; D010047:Ovalbumin / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D010587:Phagocytosis; D010588:Phagosomes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology
D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; D011480:Protease Inhibitors; D010047:Ovalbumin; D002403:Cathepsins