Publication: Caspases in virus-infected cells contribute to recognition by CD8+ T lymphocytes
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2010-05-01
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American Association of Immunologists (AAI)
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Abstract
CD8(+) cytotoxic T lymphocytes recognize infected cells in which MHC class I molecules present pathogen-derived peptides that have been processed mainly by proteasomes. Many infections induce a set of proteases, the caspases involved in apoptosis or inflammation. In this study, we report that processing and presentation of a short vaccinia virus-encoded Ag can take place also by a nonproteasomal pathway, which was blocked in infected cells with chemical inhibitors of caspases. By cleaving at noncanonical sites, at least two caspases generated antigenic peptides recognized by T lymphocytes. The sites and the peptidic products were partially overlapping but different to those used and produced by proteasomes in vitro. Antigenic natural peptides produced in infected cells by either pathway were quantitatively and qualitatively similar. Finally, coexpression of the natural vaccinia virus protein B13, which is an inhibitor of caspases and apoptosis, impaired Ag presentation by the caspase pathway in infected cells. These data support the hypothesis that numerous cellular proteolytic systems, including those induced during infection, such as caspases involved in apoptosis or in inflammation, contribute to the repertoire of presented peptides, thereby facilitating immunosurveillance.
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Amino Acid Sequence Animals Antigen Presentation Apoptosis CD8-Positive T-Lymphocytes Caspases Cell Line H-2 Antigens Histocompatibility Antigen H-2D Immediate-Early Proteins Immunodominant Epitopes Mice Mice, Inbred BALB C Molecular Sequence Data Muromegalovirus Peptides Proteasome Endopeptidase Complex Signal Transduction Vaccinia virus
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J Immunol. 2010 May 1;184(9):5193-9. doi: 10.4049/jimmunol.1000050. Epub 2010 Mar 26.