Thymus leukemia antigen (TL)-specific cytotoxic T lymphocytes recognize the alpha1/alpha2 domain of TL free from antigenic peptides.
The thymus leukemia antigens (TL) belong to the MHC class Ib family and can be recognized by CD8-dependent or -independent cytotoxic T lymphocytes (CTL) showing TL, but not H-2, restriction. We previously reported that the CTL epitope is TAP independent and in the present study we further characterize the recognition mechanism of CD8-dependent TL-specific TCRalphabeta CTL. We first prepared empty TL tetramers by way of peptide-independent folding with recombinant proteins produced in an Escherichia coli expression system, and showed that TL-specific CTL recognized TL without putative TL-associated peptide and/or post-translational modifications of TL by mammalian and insect cells. We next prepared transfectants expressing various chimeric TL molecules with mouse or human MHC class I as well as chimeric TL tetramers with recombinant proteins produced by insect cells, and demonstrated that chimeric TL whose alpha3 domain was replaced by that of H-2K(b), but not of HLA-A2, was sufficient for binding and activation of TL-specific CTL. These results indicate that TL-specific CTL recognize predominantly their alpha1/alpha2 domain as an epitope(s) and that the binding activity to the murine CD8 of the alpha3 domain of H-2K(b) is sufficient to induce their CTL activity, although it is known to be weaker than that of TL, but stronger than that of HLA. The results taken together indicate that CD8-dependent TL-specific TCRalphabeta CTL recognize an epitope(s) of the alpha1/alpha2 domain of TL free from antigenic molecules, and that CD8 plays an important role in stable interactions between TL and their corresponding TCR.
Tsujimura
Kunio
K
Division of Immunology, 1-1 Kanokoden, Chikusa-ku, Nagoya 464-8681, Japan. ktsujimu@aichi-cc.jp
Obata
Yuichi
Y
Kondo
Eisei
E
Nishida
Keiko
K
Matsudaira
Yasue
Y
Akatsuka
Yoshiki
Y
Kuzushima
Kiyotaka
K
Takahashi
Toshitada
T
D000818:Animals; D001665:Binding Sites; D016827:CD8 Antigens / Q000276:immunology / Q000378:metabolism; D022801:Complementarity Determining Regions / Q000276:immunology / Q000378:metabolism; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D051379:Mice; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D051381:Rats; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology* / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism
D016827:CD8 Antigens; D022801:Complementarity Determining Regions; D018984:Epitopes, T-Lymphocyte; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D016693:Receptors, Antigen, T-Cell, alpha-beta; C028388:thymus-leukemia antigens; D007371:Interferon-gamma