Epitopes for human CD4+ cells on diphtheria toxin: structural features of sequence segments forming epitopes recognized by most subjects.
The sequence regions of diphtheria toxin (DTX) recognized by CD4+ T cells of seven healthy humans of different major histocompatibility complex haplotypes were identified. Overlapping synthetic peptides, screening the DTX sequence, were used to test in proliferation assays unselected blood CD4+ cells, or DTX-specific CD4+ lines propagated by stimulation with DTX of blood mononuclear cells. Blood CD4+ cells and DTX-specific CD4+ lines gave consistent results. Although each subject had an individual pattern of peptide recognition, six peptide sequences (residues 271-290, 321-340, 331-350, 351-370, 411-430 and 431-450) were recognized by all subjects. In the native DTX molecule, these sequence regions are flanked by sequence loops exposed on the DTX surface. They overlap uncharged segments of the DTX sequence. These structural properties may be general requirements for immunodominance in CD4+ cell sensitization in humans.
Raju
R
R
Department of Biochemistry, College of Biological Sciences, University of Minnesota, St. Paul 55108, USA.
Navaneetham
D
D
Okita
D
D
Diethelm-Okita
B
B
McCormick
D
D
Conti-Fine
B M
BM
D000328:Adult; D000595:Amino Acid Sequence; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology*; D002460:Cell Line; D004167:Diphtheria Toxin / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology*; D004168:Diphtheria Toxoid / Q000276:immunology; D005260:Female; D006681:HLA-D Antigens / Q000235:genetics; D006801:Humans; D016056:Immunodominant Epitopes / Q000737:chemistry* / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008213:Lymphocyte Activation; D008297:Male; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology
D004167:Diphtheria Toxin; D004168:Diphtheria Toxoid; D006681:HLA-D Antigens; D016056:Immunodominant Epitopes; D010455:Peptides