Chemically unrelated mycobacterial peptides as antigens and competitors in antigen recognition by human T cells.
Understanding resistance to mycobacterial infectious diseases requires identification of antigens and epitopes (antigenic determinants) that stimulate cell-mediated immune responses. In this study, a DR1-restricted T cell epitope (residues 1 through 20) of the 19-kD protein of M. tuberculosis was identified. Peripheral blood mononuclear cells from two HLA-DR1 patients with tuberculosis responded not only to the 19-kD immunoblot fraction of M. tuberculosis but also to the peptide 1-20. A M. tuberculosis-reactive T cell clone isolated from one of the patient (whose mononuclear cells showed a stronger proliferative response to the 19-kD protein) recognized the peptide 1-20, while failed to recognize a negative control peptide (residues 65 through 85 of the 65-kD mycobacterial protein: peptide 65-85) or a negative control antigen (candida). The antigen recognition to peptide 1-20 was shown to be DR1 restricted. This MHC restriction was confirmed using a DR1-restricted mycobacterial T cell epitope as competitor. These results demonstrated that this mycobacterial competitor significantly reduced the antigen recognition of peptide 1-20. The reduction observed was dose-dependent.
Méndez-Samperio
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Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, I.P.N. Carpio y Plan de Ayala, México, D.F., México.
D000907:Antibodies, Bacterial / Q000276:immunology; D000937:Antigen-Antibody Reactions / Q000187:drug effects; D000942:Antigens, Bacterial / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology*; D001667:Binding, Competitive; D002461:Cell Line, Transformed; D018834:Chaperonin 60; D018833:Chaperonins; D015798:HLA-DR1 Antigen / Q000276:immunology*; D006360:Heat-Shock Proteins / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology*
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D018834:Chaperonin 60; D015798:HLA-DR1 Antigen; D006360:Heat-Shock Proteins; D010446:Peptide Fragments; C074119:heat-shock protein 65, Mycobacterium; D018833:Chaperonins