title: CD4 augments the response of a T cell to agonist but not to antagonist ligands.
abstract: The recognition of peptide variants by the T cell receptor (TCR) has revealed a wide range of possible responses. Here, using a series of CD4+ and CD4- variants of the same T cell hybridoma, we find that while the expression of CD4 converts weak agonists into full agonists, none of the antagonist peptides are efficiently recognized as agonists. Furthermore, in antagonist assays, little difference can be seen in the response of CD4+ and CD4- T cells. Together with previous work showing a marked difference in stability between TCR binding to agonist versus antagonist ligands, these data suggest that CD4 engagement occurs after a TCR-peptide/MHC complex has formed and that it requires a certain minimal half-life of the ternary complex to be fully engaged in signaling.
authors.affiliation: The Howard Hughes Medical Institute, Stanford University School of Medicine, California 94305, USA.
authors.forename: J
authors.initials: J
authors.lastname: Hampl
authors.forename: Y H
authors.initials: YH
authors.lastname: Chien
authors.forename: M M
authors.initials: MM
authors.lastname: Davis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015704:CD4 Antigens / Q000378:metabolism / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000502:physiology* / Q000648:ultrastructure; D016466:CHO Cells; D002999:Clone Cells; D006224:Cricetinae; D003574:Cytochrome c Group / Q000378:metabolism / Q000494:pharmacology; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006825:Hybridomas; D008024:Ligands; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D011948:Receptors, Antigen, T-Cell / Q000819:agonists* / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012680:Sensitivity and Specificity
chemical_list: D015704:CD4 Antigens; D003574:Cytochrome c Group; D000949:Histocompatibility Antigens Class II; D008024:Ligands; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell