title: Constitutive and induced expression of the individual HLA-DR beta and alpha chain loci in different cell types.
abstract: The HLA-DR subregion of the human major histocompatibility complex encodes molecules involved in the regulation of the immune response. These HLA class II molecules are transmembrane heterodimers composed of an alpha and a beta chain. The polymorphic beta chains are encoded by multiple, highly homologous loci, whereas the alpha chain is encoded by a single, nonpolymorphic locus. HLA-DR is expressed constitutively on B lymphocytes and on activated T lymphocytes. It can also be induced by interferon-gamma on most nonlymphoid cells. In a quantitative study of the expression of the individual DR beta chain loci, we have investigated: the levels of mRNA transcripts of the two functional DR beta loci (beta I and beta III) in B cells of various haplotypes; whether both beta chain loci are expressed in activated T cells and, if so, the level of expression of each; whether both loci are expressed in interferon-gamma-induced nonlymphoid cells. This analysis relied on locus-specific DR beta chain oligonucleotide probes. Expression of both the beta I and the beta III loci was observed in all cell types and in all haplotypes tested. In every case the amount of beta I mRNA was about 5 times higher than that of beta III mRNA. This indicates a controlled and coordinated regulation of the mRNA levels of these two HLA-DR loci under all conditions of major histocompatibility complex class II gene expression.
mesh_terms: D001402:B-Lymphocytes / Q000502:physiology*; D005347:Fibroblasts / Q000502:physiology; D005786:Gene Expression Regulation; D006681:HLA-D Antigens / Q000235:genetics*; D006684:HLA-DR Antigens / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007371:Interferon-gamma / Q000502:physiology; D009000:Monocytes / Q000502:physiology; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger / Q000235:genetics; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D006681:HLA-D Antigens; D006684:HLA-DR Antigens; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D007371:Interferon-gamma