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MHC Class I Presentation of an Exogenous Polypeptide Antigen Encoded by the Murine AIDS Defective Virus
Author(s) -
Yee Sungtae,
Okada Yoshiaki,
Ogasawara Kazumasa,
Omura Satoshi,
Takatsuki Akira,
Kakiuchi Terutaka,
Muno Daisaku,
Kominami Eiki,
Mizuochi Toshiaki
Publication year - 1997
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1997.tb01892.x
Subject(s) - mhc class i , biology , antigen presentation , antigen processing , lactacystin , mhc restriction , antigen , transporter associated with antigen processing , cd8 , microbiology and biotechnology , major histocompatibility complex , endoplasmic reticulum , cytotoxic t cell , brefeldin a , proteasome , biochemistry , in vitro , proteasome inhibitor , golgi apparatus , immunology
Peptides derived from endogenous proteins are presented by MHC class I molecules, whereas those derived from exogenous proteins are presented by MHC class II molecules. This strict segregation has been reconsidered in recent reports in which exogenous antigens are shown to be presented by MHC class I molecules in the phagocytic pathway. In this report, the presentation pathway of an exogenously added highly antigenic polypeptide encoded by the murine AIDS (MAIDS) defective virus gag p12 gene is investigated. A 25‐mer polypeptide (P12–25) encoded within the gag p12 region of the MAIDS defective virus was found to be effective in stimulating unprimed B6 (H‐2 b ) CD8 + T cells in vitro. The presentation of P12–25 is sensitive to cytochalasin B and D, brefeldin A and gelonin, a ribosome‐inactivating protein synthesis inhibitor, but less sensitive or resistant to lactacystin, a highly specific inhibitor of the proteasome. Interestingly, CA‐074, a selective inhibitor of cathepsin B, inhibited presentation of the polypeptide, indicating its involvement in the degradation of the P12–25 polypeptide. In fact, when P12–25 was digested with purified cathepsin B in vitro , a highly antigenic 11‐mer peptide containing the class I (H‐2D b )‐binding motif was obtained. Our results favor the phagosome/macropinosome‐to‐cytosol‐to‐endoplasmic reticulum (ER)‐to‐cell surface pathway for exogenous antigens presented by MHC class I molecules. These findings may be relevant to exploiting peptide vaccines that specifically elicit CD8 + T cell immunity in vivo.