title: Analysis of the MHC class I antigen presentation machinery in human embryonal carcinomas: evidence for deficiencies in TAP, LMP and MHC class I expression and their upregulation by IFN-gamma.
abstract: The expression of the major histocompatibility complex (MHC) class I antigens is suppressed in early post-implantation embryonic cells as well as in embryonal carcinoma (EC) cells, but could be upregulated by treatment with interferon (IFN)-gamma or retinoic acid. In a number of human and murine tumours, defects in the expression of the different components of the MHC class I antigen processing machinery, such as the proteasomal subunits LMP-2 and LMP-7 and the peptide transporters TAP-1 and TAP-2, account for impaired MHC class I surface expression. Here, we analysed the constitutive and IFN-gamma regulated mRNA and protein expression of the LMP, TAP and MHC class I molecules in the human EC line 577LM. In comparison to lymphoblastoid control cells, poor constitutive mRNA and protein expression of LMP-7, TAP-1, HLA class I, and beta 2-microglobulin, but not of TAP-2 and LMP-2, was detected in 577LM cells. The lack of MHC class I surface expression on 577LM cells could not be enhanced either by culturing cells at low temperature or by their incubation with exogenous MHC class I specific binding peptides: thus, the defective MHC class I surface expression was not only caused by impaired generation and processing of antigenic peptides. IFN-gamma treatment of 577LM resulted in a significant increase of MHC class I surface expression which was preceded by an upregulation of TAP, LMP and MHC class I transcripts as well as of TAP-1 and TAP-2, but not of LMP-2 and LMP-7, protein expression. These data suggest that human EC cell lines show a stable expression of a MHC class I low/deficient phenotype. The deficiencies associated with this phenotype involve different levels of the MHC class I restricted antigen presentation machinery and could be modified by treatment with IFN-gamma.
authors.affiliation: Johannes-Gutenberg University, IIIrd Medical Clinic, Mainz, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Seliger
authors.forename: T
authors.initials: T
authors.lastname: Dunn
authors.forename: A
authors.initials: A
authors.lastname: Schwenzer
authors.forename: J
authors.initials: J
authors.lastname: Casper
authors.forename: C
authors.initials: C
authors.lastname: Huber
authors.forename: H J
authors.initials: HJ
authors.lastname: Schmoll
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis*; D017951:Antigen Presentation / Q000276:immunology*; D000956:Antigens, Viral / Q000276:immunology; D018236:Carcinoma, Embryonal / Q000276:immunology*; D003546:Cysteine Endopeptidases; D003587:Cytomegalovirus / Q000276:immunology; D015488:HIV Antigens / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000502:physiology*; D009097:Multienzyme Complexes; D010455:Peptides / Q000276:immunology; D046988:Proteasome Endopeptidase Complex; D014176:Protein Biosynthesis; D013696:Temperature; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D000956:Antigens, Viral; D015488:HIV Antigens; D015395:Histocompatibility Antigens Class I; D009097:Multienzyme Complexes; D010455:Peptides; C073119:TAP1 protein, human; C071313:LMP-2 protein; C071692:TAP2 protein, human; D007371:Interferon-gamma; D003546:Cysteine Endopeptidases; C077436:LMP7 protein; D046988:Proteasome Endopeptidase Complex