title: Relative expression levels of the HLA class-I proteins in normal and HIV-infected cells.
abstract: The expression level of HLA class-I proteins is known to influence pathological outcomes: pathogens downregulate HLA to evade host immune responses, host inflammatory reactions upregulate HLA, and differences among people with regard to the steady-state expression levels of HLA associate with disease susceptibility. Yet precise quantification of relative expression levels of the various HLA loci is difficult because of the tremendous polymorphism of HLA. We report relative expression levels of HLA-A, HLA-B, HLA-C, and HLA-E proteins for the specific haplotype A*02:01, B*44:02, C*05:01, which were characterized using two independent methods based on flow cytometry and mass spectrometry. PBLs from normal donors showed that HLA-A and HLA-B proteins are expressed at similar levels, which are 13-18 times higher than HLA-C by flow cytometry and 4-5 times higher than HLA-C by mass spectrometry; these differences may reflect variation in the conformation or location of proteins detected. HLA-E was detected at a level 25 times lower than that of HLA-C by mass spectrometry. Primary CD4(+) T cells infected with HIV in vitro were also studied because HIV downregulates selective HLA types. HLA-A and HLA-B were reduced on HIV-infected cells by a magnitude that varied between cells in an infected culture. Averaging all infected cells from an individual showed HLA-A to be 1-3 times higher and HLA-B to be 2-5 times higher than HLA-C by flow cytometry. These results quantify substantial differences in expression levels of the proteins from different HLA loci, which are very likely physiologically significant on both uninfected and HIV-infected cells.
authors.affiliation: Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702;
authors.forename: Richard
authors.initials: R
authors.lastname: Apps
authors.affiliation: Protein Characterization Laboratory, Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702;
authors.forename: Zhaojing
authors.initials: Z
authors.lastname: Meng
authors.affiliation: AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702; and.
authors.forename: Gregory Q
authors.initials: GQ
authors.lastname: Del Prete
authors.affiliation: AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702; and.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Lifson
authors.affiliation: Protein Characterization Laboratory, Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702;
authors.forename: Ming
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, MD 21702; Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139 carringm@mail.nih.gov.
authors.forename: Mary
authors.initials: M
authors.lastname: Carrington
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000276:immunology*; D056426:Genetic Loci / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology* / Q000473:pathology; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D008297:Male
chemical_list: D015395:Histocompatibility Antigens Class I