title: Differential activation of T cells by natural antigen peptide analogues: influence on autoimmune and alloimmune in vivo T cell responses.
abstract: Recent studies using synthetic altered peptide ligands (Analogues) have led to the fine dissection of TCR-mediated T cell functions elicited by Ag recognition. Certain Analogues behave as full agonists of the antigenic peptide while others are partial agonists in that they only trigger selected T cell functions. Additionally, peptide Analogues can behave as antagonists by inhibiting functions of T cell clones when coincubated with the wild-type peptide. In fetal thymic organ cultures, synthetic altered peptide ligands can impact T cell repertoire selection. However, the influence of naturally occurring peptide Analogues on T cell immunity in vivo remains hypothetical. We previously reported that, in B10.A mice, immunogenicity and tolerogenicity of the self-MHC class I peptide, Ld 61-80, were influenced by the presentation of a cross-reactive self-peptide, Kk 61-80. Here, we show that Kk 61-80 self-peptide represents a partial agonist of Ld 61-80 in that it induced the proliferation but not the lymphokine production of Ld 61-80-primed T cells. Next, we showed that presentation of Kk 61-80 Analogue peptide mediated T cell tolerance toward Ld 61-80 self-peptide. Alternatively, when Ld protein represented an alloantigen displayed on transplanted cells, immunization with Kk 61-80 Analogue sensitized recipient mice to Ld 61-80 peptide, thus inducing potent immune responses to donor cells. These results show that the presentation of natural Analogue peptides may represent an essential component of T cell responses involved in autoimmunity and transplant rejection.
authors.affiliation: University of California at San Francisco School of Medicine, Department of Surgery, Immunogenetics and Transplantation Laboratory at Davies Medical Center, 94114, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Soares
authors.forename: P L
authors.initials: PL
authors.lastname: Orr
authors.forename: M R
authors.initials: MR
authors.lastname: Garovoy
authors.forename: G
authors.initials: G
authors.lastname: Benichou
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015551:Autoimmunity; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D007114:Immunization; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000096:biosynthesis; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D014184:Transplantation, Homologous / Q000276:immunology
chemical_list: D015395:Histocompatibility Antigens Class I; D008222:Lymphokines; D010446:Peptide Fragments; D007371:Interferon-gamma