Inhibition of allorecognition by an H-2Kb-derived peptide is evidence for a T-cell binding region on a major histocompatibility complex molecule.
The class I and class II major histocompatibility complex (MHC) antigens are polymorphic cell-surface glycoproteins that present antigenic peptides to T lymphocytes in the generation of immune responses. While much is known about the recognition and processing of antigens, the nature of T-cell recognition sites on MHC molecules is poorly understood. Both structural and functional studies have suggested that the two major alpha-helical regions of the class I MHC molecule not only define the site for binding of antigenic peptide but also provide potential sites for interaction of the MHC molecule with the T-cell receptor. A peptide derived from one of these regions on the H-2Kb molecule, peptide Kb163-174, was previously shown to specifically inhibit the stimulation of an alloreactive T-cell hybridoma. To further investigate the role of this region in the recognition of H-2Kb, the effects of peptide Kb163-174 on allospecific T-cell lines and clones were studied. When peptide Kb163-174 was cocultured with either an H-2Kbm10 anti-H-2Kb cytotoxic T-lymphocyte (CTL) clone or a CTL line, this peptide inhibited lysis of H-2Kb targets. Pretreatment experiments showed that the blockade was due to interaction of the peptide with the effector T cells. Surprisingly, peptide Kb163-174 also inhibited lysis of H-2Kb targets by H-2Kbm1-, H-2Kbm3-, H-2Kbm6, and H-2Kbm8-anti-H-2Kb CTLs. These CTLs, which identify multiple antigenic sites on H-2Kb in the alpha 1 and alpha 2 domains, are not directed against amino acid residues 163-174 of H-2Kb. In addition, peptide Kb163-174 specifically blocked lysis of only H-2Kb and not H-2Ld targets by a single bulk CTL culture that was alloreactive on both H-2Kb and H-2Ld. These results indicate that peptide Kb163-174 interferes with T-cell receptor engagement of a contact site on the H-2Kb molecule. Thus, amino acid residues 163-174 define a site used by many alloreactive T cells to engage the H-2Kb molecule.
Schneck
J
J
Molecular Biology Section, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892.
Munitz
T
T
Coligan
J E
JE
Maloy
W L
WL
Margulies
D H
DH
Singer
A
A
D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D006183:H-2 Antigens / Q000276:immunology*; D006801:Humans; D008285:Major Histocompatibility Complex; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000494:pharmacology*; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D009842:Oligopeptides