title: The self-directed T cell repertoire against mouse lysozyme reflects the influence of the hierarchy of its own determinants and can be engaged by a foreign lysozyme.
abstract: The T cell repertoire is shaped by the processes of positive and negative selection. We have previously shown that mice are tolerant to a native self-Ag, mouse lysozyme (ML), but they respond vigorously when challenged with different ML peptides ("cryptic" self-determinants). In this study, we have addressed the issue of the physiological significance of both the hierarchy (dominance/crypticity) of self-determinants within ML and the anti-cryptic, self (ML)-directed T cell repertoire. Our results demonstrate that there are several ML peptides that bind well to MHC but are totally nonimmunogenic when tested for proliferative T cell response and cytokine secretion: a subset of these peptides presumably represent the originally dominant self-determinants of ML, which have rendered the T cells tolerant during thymic selection. Other ML peptides, which bind well to MHC and are immunogenic, correspond to the cryptic determinants of ML: T cells against cryptic ML determinants escape tolerance induction. Thus, the mature T cell repertoire against ML bears the direct imprint of the hierarchy of self (ML)-determinants. Interestingly, hen egg white lysozyme could prime T cells in vivo that were cross-reactive with certain cryptic ML determinants, and vice versa, without requiring any coimmunization with the foreign lysozyme and ML peptide(s). Moreover, repeated, deliberate priming and expansion of T cells by hen egg white lysozyme immunization concomitantly enhanced T cell response to such cross-reactive ML determinants. This reciprocal self-foreign determinant cross-reactivity may play a previously unrecognized, but crucial, role in the expansion and diversification of self-reactive clones in the autoimmune response.
authors.affiliation: Department of Microbiology, University of California, Los Angeles 90095, USA. Kamal@liai.org
authors.forename: K D
authors.initials: KD
authors.lastname: Moudgil
authors.forename: S
authors.initials: S
authors.lastname: Southwood
authors.forename: A
authors.initials: A
authors.lastname: Ametani
authors.forename: K
authors.initials: K
authors.lastname: Kim
authors.forename: A
authors.initials: A
authors.lastname: Sette
authors.forename: E E
authors.initials: EE
authors.lastname: Sercarz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000008:administration & dosage* / Q000276:immunology; D001665:Binding Sites / Q000276:immunology; D002645:Chickens / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006183:H-2 Antigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006239:Haplotypes; D007279:Injections, Subcutaneous; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D009113:Muramidase / Q000008:administration & dosage / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*
chemical_list: D000941:Antigens; D018984:Epitopes, T-Lymphocyte; D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D010446:Peptide Fragments; D009113:Muramidase