title: Cell phenotype dependent expression of MHC class I antigens in Burkitt's lymphoma cell lines.
abstract: Burkitt's lymphoma (BL) is a highly malignant B cell tumor characterized by three types of chromosomal translocation which constitutively activate the c-myc oncogene by juxtaposing it to Ig coding sequences. Epstein-Barr virus (EBV) infection, hyperendemic malaria and HIV-caused immunosuppression are thought to contribute to the pathogenesis of the tumor. Cell lines derived from EBV carrying and EBV negative BLs often show altered MHC class I antigen expression. The defects include a lower expression of all HLA class I antigens compared to EBV transformed normal B-blasts, and selective down-regulation of certain HLA-A and HLA-C alleles. As a consequence BL cells are often resistant to cytotoxic T lymphocyte (CTL) mediated destruction. Alleles selective down-regulations are found only in cell lines that maintain the tumor cell phenotype while shift towards a more activated 'B-blast like' phenotype is accompanied by HLA class I up-regulation. A similar pattern of HLA class I expression can be found in a subpopulation of germinal center B cells which express a 'BL like' phenotype. Our findings suggest that the HLA class I expression of BL cells reflects the characteristics of the normal B cell precursor and is probably not the result of immune selection.
authors.affiliation: Department of Tumor Biology, Karolinska Institute, Stockholm, Sweden.
authors.forename: M G
authors.initials: MG
authors.lastname: Masucci
authors.forename: E
authors.initials: E
authors.lastname: Klein
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis; D001402:B-Lymphocytes / Q000276:immunology; D002051:Burkitt Lymphoma / Q000276:immunology* / Q000382:microbiology; D002460:Cell Line; D015536:Down-Regulation; D015234:HLA-A Antigens / Q000378:metabolism; D015235:HLA-B Antigens / Q000378:metabolism; D015236:HLA-C Antigens / Q000378:metabolism; D004854:Herpesvirus 4, Human / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D016130:Immunophenotyping
chemical_list: D015703:Antigens, CD; D015234:HLA-A Antigens; D015235:HLA-B Antigens; D015236:HLA-C Antigens; D015395:Histocompatibility Antigens Class I