MHC class I/peptide stability: implications for immunodominance, in vitro proliferation, and diversity of responding CTL.
Infection of BALB/c mice with Listeria monocytogenes primes CD8+ cytotoxic T cells specific for four different H2-Kd-restricted peptides. In vitro restimulation of L. monocytogenes immune splenocytes with each of these peptides resulted in larger T cell responses to p60 217-225 and mpl 84-92 than to LLO 91-99 and p60 449-457. Direct frequency analyses of immune splenocytes, however, revealed that LLO 91-99 and p60 217-225 elicit dominant T cell responses, while p60 449-457 and mpl 84-92 elicit minor, subdominant responses. Restimulation of immune splenocytes with a range of peptide concentrations revealed that T cells with dominant specificities respond optimally to low peptide concentrations, while T cells specific for subdominant epitopes expand maximally to high peptide concentrations. This disparity correlates with the stability of H2-Kd/epitope complexes: the two dominant epitopes form stable complexes, while the subdominant epitopes form less stable complexes with H2-Kd. Interestingly, T cells specific for LLO 91-99 and p60 217-225 express more complex TCR-Vbeta repertoires than p60 449-457- and mpl 84-92-specific T cells. Thus, in our system, dominant T cell responses have relatively diverse TCR repertoires and are specific for peptides that form stable complexes with MHC class I molecules. Determining the precise roles of epitope/MHC class I stability and TCR repertoire in the generation of dominant T cell responses will require further investigation.
Busch
D H
DH
Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT 06520, USA.
Pamer
E G
EG
D000818:Animals; D017951:Antigen Presentation; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D015395:Histocompatibility Antigens Class I / Q000737:chemistry / Q000276:immunology*; D008089:Listeria monocytogenes / Q000276:immunology*; D008088:Listeriosis / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology
D015395:Histocompatibility Antigens Class I; D010455:Peptides; D011948:Receptors, Antigen, T-Cell