Apparent HLA DR triplet due to the coexpression of a DRB5-encoded molecule on a DR1 haplotype.

HLA DR1 molecules are coded by a single polymorphic DRB1 gene. We have observed rare DR1 cells in one Caucasoid family and three unrelated individuals that also reacted with some anti-DR2 sera. Since the second DR antigen was normally expressed, these cells appeared as triplets. Contrary to serology, the cells were not typed by HTCs defining Dw2, Dw12, and Dw21. Further investigations on these unusual DR1+2* haplotypes were conducted by DNA oligotyping and by sequencing of the DRB first-domain exon. The results showed that these DR1 haplotypes, besides their DRB1*0101 allele, carried also a DRB5*0101 allele.     

HLA-D-DR relationships: PLT studies of HLA-D specificities associated with DR1, DR2, and DR4

The primed lymphocyte test (PLT) detects gene products of the HLA-D-DR region which activate the secondary (memory) response of MLC stimulated T cells. In the present study attempts were made to determine whether different HLA-D alleles associated with the same DR, such as DR1, 2, and 4 can be discriminated by PLT typing. PLTs were generated by using, as responders and primary MLC stimulators, HLA-D different HTCs which shared all DR groups (major DR, supertypic MT and second locus MB) or only the MT or MB groups. As secondary stimulators, lymphocytes from an HLA-D selected panel of 72 individuals were used. PLTs raised in DR identical responder-primary stimulator combinations were able to discriminate between the different HLA-D antigens associated with the same DR. In contrast, when priming was performed in combinations differing for the major DR group, the restimulation response was highly associated with the DR specificity of the primary stimulator, regardless of whether or not this was compatible with the responding HTC for the MT or MB groups.

This data indicate that the specificity of primed lymphocytes largely depends on the combinations used for priming and that the memory response can be activated by both HLA-D and DR antigens. The dissociation of HLA-D from DR by PLT typing might provide a useful tool for further analysis of this HLA region.     

Molecular characterization of a recombinant HLA-DR1/DR2 haplotype

Serologic analysis of two families identified an HLA-DR haplotype in which DR1 and DR2 cosegregated. DNA-RFLP analysis of these families with an HLA-DRB probe revealed a pattern of hybridization suggestive of a recombination between DR1 and DR15. Following amplification, cloning, and nucleotide sequencing of HLA-DRB-gene second-exon DNA sequences, three DRB amplification products associated with the novel haplotype were identified: these corresponded to DRB1*0101, DR2 pseudogene, and DRB5*0101. Clones representing the DRB1*1501 and DR1 pseudogenes were not identified: oligonucleotide typing with DRB1*1501-specific probes confirmed the absence of this gene within the DR1/DR2 haplotype. We postulate that the DR1/DR2 haplotype represents a recombinant between those of DR1-Dw1 and DR15-Dw2, and that the crossing-over may have been between the DRB1*0101 gene and the DR2 pseudogene. This is further supported by DNA-RFLP analysis with HLA-DQB and DQA CDNA probes, which revealed conserved linkage genes between the DQB1*0501, DQA1*0101, and DRB1*0101 genes.     

A description of a new DR allele, DRB1*1113

Abstract: We have discovered a previously unpublished HLA-DRB1 allele, observed in a patient (SB), his mother, and one sibling. The undefined allele gave sporadic positive reactions with sera in the DR52-associated group. SSOPH analysis utilizing both generic and group specific primers and probes also gave ambiguous results. SB typed clearly as a DRB 1*0301 (paternal allele) but the DNA from SB also bound probes specific for DRB 1*14 and DRB1*11. Sequencing revealed that the undefined allele was similar to a DRB 1*14 allele with a segment of sequence found in DRB1*11 alleles. The patient was MLC reactive with donors who express DRB1*0301, *1401 and *0301, *11 and was nonreactive solely to DRB 1*0301 (Dw3) homozygous typing cells.     

Identification of a novel DR4 allele, DRB1*0442

A new DRB1 allele encoding DR4, DRB1*0442, was identified in three Caucasian siblings by reverse in-line hybridization and defined by sequencing based typing. The DRB1*0442 allele differs from DRB1*0404 by a single nucleotide at position 227 (T-->A) of codon 47 in exon 2. At the amino acid level, this substitution results in a change from tyrosine to phenylalanine. Serologically, the new allele appears to retain the DR4 antigenicity; however, this substitution may affect peptide-binding specificity.     

DR6 in Koreans DR11 Frequently acts as a recipient gene to create DR13 alleles

DR6 is a complex allele family composed of at least 16 different alleles. Although 25% of Koreans express DR6 alleles, this allele family has not been well studied in the population. DNA samples obtained from 252 unrelated individuals were screened by PCR using Taq DNA polymerase and a DRB1 group-specific PCR primer set that amplifies the polymorphic second exon of DR3, DR11, and DR6 DRB1 alleles. To identify the DR6 allelic frequencies in this population, PCR-positive samples were further analyzed by dot-blot hybridization using digoxigenin-labeles SSOPs. In this process, a new DRB1 allele was identified by its unique hybridization pattern and was further characterized by direct sequencing after PCR. The new DRB1 sequence is similar to DRB1*1101, differing at codon 47 (TAC[Tyr]/ TTC[Phe]) and at codon 58 (GCC[Ala]/GAG[Glu]). Based on sequence comparisons as well as its DRB3 and DQ associations, the new allele may have arisen by a gene conversion event from DRB1*1101. The resultant DR molecule bears DR6 serologic determinants as determined by serologic typing and, based on sequence, is probably a DR13 and not a DR14 allele. These data suggest that the DR11 allele has frequently acted as a recipient gene in the gene conversion events that created the subfamily of DR13 alleles, DRB1*1303, *1304, *1305, and the new allele described here.     

A division of HLA-DQw1 associated with DR1, DR1x-DQw1, DR2 short, DRw10, and DRw14. I. Definition by alloantiserum LY 1327

We have identified an alloantiserum, LY 1327, directed against part of DQw1-positive cells. This split of DQw1 includes DR1, DR1x, DR2sh, DRw10, and DRw14; the other DQ-associated specificities, -DR2 long and DRw13, are unreactive. Segregation was ascertained in 11 informative Caucasoid families and in 33 genotyped individuals. DR1x refers to a specificity typing as DR blank DQw1, detected by certain anti-DR1 sera and recognized cellularly by HTC DwBON DR blank DQw1 (A. Cambon, Toulouse). Biochemical analysis by two-dimensional gel electrophoresis and DNA analysis by restriction fragment length polymorphism will be discussed since they support the existence of this division of DQw1.     

Molecular genetics of HLA-DR ''Br'': allogenotypes of DR1 and DR ''Br'' are indistinguishable

HLA-DR1 and DR 'Br' allogenotype patterns, generated using several restriction endonucleases and visualised using four HLA-DR beta cDNA probes in Southern analysis, are indistinguishable. We suggest that HLA-DR 'Br' may be a variant of the HLA-DR1 allele.     

多巴胺受体蛋白在大鼠心肌肥厚时的表达变化

目的:观察多巴胺受体（DR）1和2 mRNA和蛋白质在大鼠病理性心肌肥厚时的表达情况。 方法:应用肾动脉缩窄术复制Wistar大鼠心肌肥厚的动物模型。于术后35 d取心脏,测定心肌肥大指数，左室内压，V-G染色观察胶原含量。应用心肌原位杂交和RT-PCR，免疫荧光，Western blotting结合图像分析系统分别检测心肌组织中多巴胺受体D1、D2 mRNA 和蛋白质的表达变化。 结果:DR1、DR2 mRNA在正常大鼠心肌组织有表达，其中血管平滑肌细胞内DR2的分布多于心室肌和心房肌细胞。模型组左心肥大明显，表现为室内压显著升高，胶原含量增多;模型组心室肌DR1和 DR2 mRNA和蛋白质的含量均明显低于假手术组。 结论:正常大鼠心肌组织存在DR1和 DR2 mRNA和蛋白质的表达，心肌肥厚时其表达明显减低，两者的关系及可能机制有待于进一步研究。     

Six new DR52-associated DRB1 alleles, three of DR8, two of DR11, and one of DR6, reflect a variety of mechanisms which generate polymorphism in the MHC

We have sequenced DNA from six new DR52-associated DRB1 alleles initially detected by PCR/SSOP analysis. Three DR8 associated alleles differed from previously known alleles by single nucleotide substitutions. DRB1*0807 and DRB1*0811 both vary from DRB1*08021 at codon 57 resulting in two different amino acids at this residue. DRB1 *0807 was identified in samples of Brazilian origin while *0811 was identified among samples from the Tlingit Native American population of Southeast Alaska. DRB1*0814, identified in a family of Chinese origin, differed from DRB1*08032 at codon 12 at both the nucleotide and the amino acid level. In addition, two alleles of DR11, DRB1*1113 and *1119, were each detected in Caucasian individuals. DRB1*1113 differs from other DR11 alleles at codons 37, 67, 70 and 74, while DRB1*1119 differs from *1101 by a single nucleotide substitution at codon 67. Finally, DRB1*1418 was detected in a sample from an Asian or Pacific Islander and shares sequences with several other DR52-associated DRB 1 alleles. These six DRB 1 alleles appear to have been generated by either gene conversion events, DRB1*1113 and * 1418, or by point mutations, DRB1*0814, *0807, *0811 and *1119, although the single nucleotide substitutions found in the latter three alleles are also present in at least one other DRB1 allele and, therefore, could have been the product of gene conversions.     

DR and DQ beta cDNA sequences associated with a DR2 haplotype

Three cDNA clones encoding a DQ beta and two DR beta polypeptides have been isolated and sequenced from an American black individual expressing a DR2,DQw1 haplotype. The sequences of the cDNA clones are identical to previously described DR and DQ sequences from a DR2,Dw2 cell. The differences between DQw1-associated beta chains from DR2 and DR1 haplotypes is substantial, although a DQw1-specific sequence can be identified. The identical DQ and DR beta sequences found in unrelated individuals from different racial backgrounds suggests that class II structural polymorphism within the human population will be limited.     

HLA-DRB1 first domain sequence for a novel DR4 allele designated DRB1*0413

A novel DR4 allele, DRB1*0413, was identified in a Caucasian individual "LEV" having the HLA phenotype A2; B51,14; DR4,7; DQw3,w2. DRB1*0413 is a DRB1*0401-variant differing from DRB1*0401 only at codon 86 where valine is present instead of glycine.     

Binding of collagen II peptides to several subtypes of DR4 and DR1 molecules.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by a chronic inflammation of the synovial membrane. Several studies have shown that the susceptibility towards RA is confered by some HLA-DR alleles such as DR401, 404, and 101. We studied the binding of overlapping peptides of the CB11 fragment of the human collagen II on DR molecules associated or not associated with disease susceptibility. The experiments were performed by binding inhibition of the biotinylated HA (306-318) peptide on human homozygous lymphoblastoid B cell lines expressing the molecules implicated (DR401 and DR101) or not (DR402 and DR103) in RA. Among 23 peptides of collagen II tested, we highlighted 5 peptides capable of binding on the molecules associated with RA. Three of these peptides contain the specific anchor residues to bind DR401 or DR101 molecules. One of them strongly inhibited the binding of HA on DR401 and DR101, but not on DR103. This peptide was directly biotinylated and will be used in direct binding experiments on other DR molecules. The immunogenicity of these peptides will be also assessed on T cells obtained from blood or synovial membrane of several patients. Altogether these results will allow to define immunogenic collagen II epitopes potentially implicated in RA.     

DR4Dw4/DR53 molecules contain a peptide from the autoantigen calreticulin

Abstract: Rheumatoid arthritis (RA) occurs more frequently in HLA-DR4⁺ individuals than in those who do not express this MHC class II molecule. Although the role of this genetic factor in the immunopathology of this autoimmune disease is unclear, the association of RA with HLA-DR4 may indicate that DR4 molecules present autoantigen(s) to T cells. Here we report the analysis of naturally processed peptides, eluted from a mixture of HLA-DR4Dw4 (DRB1*0401) and DR53 (DRB4* 0101) molecules isolated from an RA patient-derived EBV-transformed B cell line. Several (size variants of) self-peptides originating from the autologous molecules HLA-A2, HLA-Cw9, HLA-B62, HLA-DR4Dw4 and HLA-DR53, were identified. We also found a sequence that has no homology to any protein in the SwissProt protein sequence databank, and a peptide identical to an internal fragment of the autoantigen calreticulin. The association of the identified peptides with cells expressing HLA-DR4Dw4/DR53 was confirmed by peptide binding analysis. In agreement with previously described peptide binding motifs for DR4Dw4, most peptides contained an aromatic residue (Phe, Tyr, Trp) at relative position i and a small hydroxyl-containing residue (Ser, Thr) at i+5. Our findings indicate that in RA patient-derived EBV-transformed B cells DR4Dw4/ DR53 molecules present a peptide from the autoantigen calreticulin. Interestingly, autoantibodies against calreticulin have been found in various rheumatic diseases, including rheumatoid arthritis. Thus, the analysis of HLA class II-bound peptides can lead to the identification of putative T helper epitopes, which might be involved in the immunopathology of autoimmune diseases.