Direct sequence identification and kinetic analysis of an MHC class I-restricted Listeria monocytogenes CTL epitope.
Murine infection with the intracellular bacterium Listeria monocytogenes elicits MHC class I-restricted CTL with specificity for multiple bacterial peptides. The variety and relative abundance of self-peptides bound by MHC molecules make identification of pathogen-derived peptides difficult. In this report, the sequence of a pathogen-derived CTL epitope is determined by direct analysis of peptides extracted from MHC class I molecules. The epitope, p60 217-225, is presented to L. monocytogenes-specific CTL by the H-2Kd MHC class I molecule and is derived from p60, a secreted invasion-associated protein. Quantitation of p60 217-225 in infected cells shows that this epitope is detectable within 2 h of infection and, after a 9-h infection, there are over 3000 epitopes per infected cell. This contrasts with listeriolysin 91-99, the other major L. monocytogenes epitope, which is present in quantities below 200 epitopes per cell until 5 h of infection and reaches 800 epitopes per cell 9 h after infection. This report shows that identifying new T lymphocyte epitopes by direct sequence analysis of peptides isolated from MHC molecules is feasible. Furthermore, kinetic and quantitative analysis of T cell epitopes in infected cells is a useful approach to investigate the multispecific CTL response to complex intracellular pathogens.
Pamer
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Infectious Diseases Section, Yale University School of Medicine, New Haven, CT 06510.
D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000737:chemistry*; D003602:Cytotoxicity, Immunologic; D000939:Epitopes; D006183:H-2 Antigens / Q000378:metabolism*; D007111:Immunity, Cellular; D007700:Kinetics; D008089:Listeria monocytogenes / Q000276:immunology*; D008088:Listeriosis / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology / Q000378:metabolism
D000942:Antigens, Bacterial; D000939:Epitopes; D006183:H-2 Antigens; D010455:Peptides