Differential expression of human major histocompatibility class I loci: HLA-A, -B, and -C.
Expression of the human class I MHC loci, HLA-A, -B, and -C, was examined by reverse transcription and competitive PCR with locus-specific primers. This approach allows unambiguous identification of target sequences by analysis of the amplified products. JY and Pala lymphoblastoid B cells express more HLA-A than HLA-B mRNAs and little HLA-C mRNA. Raji Burkitt lymphoma and HeLa carcinoma cells express approximately equal amounts of HLA-A and HLA-C mRNAs but less HLA-B mRNA. Jar trophoblast cells express no HLA class I mRNAs. Surprisingly, K562 leukemia cells express significant amounts of HLA-C mRNA. However, K562 cells contain no detectable HLA-A or -B mRNAs, suggesting that these loci are regulated independently. Furthermore, cultured endothelial cells and smooth muscle cells express low, approximately equal amounts of HLA-A, -B, and -C mRNAs, whereas donor-matched, EBV transformed B cells express much more HLA-B mRNA, suggesting that cell type dependent regulation underlies differential locus expression. Finally, expression of HLA class I molecules on the cell surface correlates with total HLA mRNAs but not with mRNAs encoded by any one locus. Differential expression of these HLA class I loci may contribute to cell-type dependent immune reactions by preferentially presenting distinct peptides to T cells.
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Department of Pathology and the Molecular Cardiobiology Program, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, CT 06536, USA. david.johnson@yale.edu
D001667:Binding, Competitive / Q000235:genetics; D002460:Cell Line; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000235:genetics / Q000276:immunology; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000276:immunology*; D005805:Genes, MHC Class I; D005819:Genetic Markers / Q000276:immunology; D015234:HLA-A Antigens / Q000096:biosynthesis / Q000235:genetics; D015235:HLA-B Antigens / Q000096:biosynthesis / Q000235:genetics; D015236:HLA-C Antigens / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D021141:Nucleic Acid Amplification Techniques; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D005819:Genetic Markers; D015234:HLA-A Antigens; D015235:HLA-B Antigens; D015236:HLA-C Antigens; D012333:RNA, Messenger