title: Cytotoxic T cell recognition of an endogenous class I HLA peptide presented by a class II HLA molecule.
abstract: Human leukocytes were stimulated in vitro with peptides corresponding in sequence to the highly variable helix of the alpha 1 domain of various HLA-B and -C molecules. A CD4+ CD8- cytotoxic T cell line, CTL-AV, that is specific for the HLA-B7 peptide presented by HLA-DR11.1 was obtained. The HLA-DR11.2 molecule, which only differs at three residues from HLA-DR11.1, did not present the HLA-B7 peptide to CTL-AV. Peptides from the alpha 1 domain helix of other HLA-A and HLA-B molecules, but not HLA-C molecules, competed with the HLA-B7 peptide for binding to HLA-DR11.1. A cell line (WT50) that coexpresses HLA-B7 and HLA-DR11.1 was killed by CTL-AV in the absence of any added HLA-B7 peptide. The processing and presentation of HLA-B7 in these cells appears to be through the endogenous, and not the exogenous, pathway of antigen presentation. Thus, Brefeldin A inhibits presentation and chloroquine does not. Furthermore, introduction of purified HLA-B7 molecules into HLA-DR11.1+, HLA-B7- cells by cytoplasmic loading via osmotic lysis of pinosomes, but not by simple incubation, rendered them susceptible to CTL-AV killing. These results provide an example of class II major histocompatibility complex (MHC) presentation of a constitutively synthesized self protein that uses the endogenous pathway of antigen presentation. They also emphasize the capacity for presentation of MHC peptides by MHC molecules.
authors.affiliation: Department of Cell Biology, Stanford University School of Medicine, California 94305.
authors.forename: B P
authors.initials: BP
authors.lastname: Chen
authors.forename: A
authors.initials: A
authors.lastname: Madrigal
authors.forename: P
authors.initials: P
authors.lastname: Parham
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D020126:Brefeldin A; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens; D002460:Cell Line; D002738:Chloroquine / Q000494:pharmacology; D003517:Cyclopentanes / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007962:Leukocytes / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology / Q000494:pharmacology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D000900:Anti-Bacterial Agents; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D015704:CD4 Antigens; D016827:CD8 Antigens; D003517:Cyclopentanes; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; D020126:Brefeldin A; D002738:Chloroquine