Hla-DR Typing by Radioimmunoassay

A monoclonal antibody, CC11.23, with monomorphic specificity predominantly for products of the HLA-DQ subregion, has been used to demonstrate primary structural variation among DQ molecules. Two cell lines of each haplotype (DRI-7) were radiolabeled with [3Htyrosne.a and ( chains were Isolated from CC11.23-reactive preparations, and their amino-terminal tyrosine sequences were determined. Each DR haplotype (with the exception of DRw6) * Although the DR a chain appears to be nonpolymorphic(1), a growing body of evidence suggests that the DQ a chain is polymorphic (8-11). Comparisons of genomic and/or cDNA sequences of DQ a chain from several cell lines have demonstrated that multiple differences exist among the few haplotypes examined (9, 10). Polymorphic variation of both the a and ( chain of the DQ molecule is consistent with the extensive polymorphism exhibited by its murine counterpart, the I-A molecule. Both the a and (8 chains of I-A molecules display variation from one haplotype to another (15). In addition to these extensively polymorphic I-A chains, the mouse expresses a modestly polymorphic I-E a chain and a highly polytnorphic I-E (3 chain. A similar situation appears to exist within the human counterpart ofI-E, the HLA-DR subregion. Existing data are consistent with the notion that the DR a chain is invariant, or at best only modestly variant, but that the DR ( chain, the DQ a chain, and the DQ P chain are polymorphic among different haplotypes.Shortly after the demonstration of allelic polymorphism of murine class II molecules, evidence was presented for the formation of hybrid molecules in F1 animals, providing a possible molecular mechanism for the phenomenon of gene complementation (16,17). This trans gene complementation increases the alloantigen repertoire in heterozygotes. In humans, tranls association has recently been reported for DQ molecules by two-dimensional gel electrophoresis (18

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confidence: 79%

“…(1), a growing body of evidence suggests that the DQ a chain is polymorphic (8)(9)(10)(11). Comparisons of genomic and/or cDNA sequences of DQ a chain from several cell lines have demonstrated that multiple differences exist among the few haplotypes examined (9,10).…”

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confidence: 99%

Allelic polymorphism and transassociation of molecules encoded by the HLA-DQ subregion.

Giles¹,

DeMars²,

Chang³

et al. 1985

“…The DC1 specificity was first described by Tosi et aL (14) By testing a battery of human alloantisera for binding to a membrane glycoprotein preparation of"HLA-DR" from the cell line Daudi (DRw6,blank), they were able to define three populations of molecules carrying the specificities DRw6, DC1, and DC2. They showed that both the DRw6 and DC1 molecules had a two-chain structure but were not able to resolve a difference in the molecular weights of the DC1 and DRw6 heavy chains.…”

Section: Discussionmentioning

confidence: 99%

“…Ofparticular interest are several series ofserological specificities expressed on B cells found in linkage disequilibrium.with various DR specificities. These have been termed DC (14), MB (15), MT (16), and LB (17) antigens by various investigators. At present, there is not a consensus as to whether these new specificities represent supertypic determinants on the DR molecule or determinants on a molecule distinct from HLA-DR.…”

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confidence: 99%

Human B-cell alloantigens DC1, MT1, and LB12 are identical to each other but distinct from the HLA-DR antigen

Shackelford

Mann

Rood

et al. 1981

179

Some human B-lymphoblastoid cell lines are shown to express at least two types ofIa-like antigens. One antigen is defined by alloantisera to HLA-DR, and the other antigen is defined by alloantisera and a monoclonal antibody to the specificities DC1, MT1 (MB1), and LB12, which are in linkage disequilibrium with HLA-DR. The subunits of the DC1 molecule differ from those of the DR molecule. The light chains of both molecules are structurally polymorphic.

“…Three different class II heterodimers, denoted DR (2), DC (5), and SB (6), have been identified by immunochemical techniques and primed lymphocyte typing. Also a fourth antigen called BR has been proposed (7).…”

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confidence: 99%

Exon-intron organization and complete nucleotide sequence of a human major histocompatibility antigen DC beta gene.

Larhammar¹,

Hyldig‐Nielsen²,

Servenius³

et al. 1983

135

We have determined the complete nucleotide sequence of a human class II histocompatibility antigen DCl gene. The gene spans more than 7 kilobases and contains five exons corresponding to the different domains of the DC,8 polypeptide. The exon-intron organization is thus analogous to that of class II antigen a-chain genes, class I antigen heavy chain genes, and the constant parts of immunoglobulin genes, emphasizing further the evolutionary relationship among these molecules. The mature polypeptide deduced from the DC.8 gene shows 93% and 88% homology, respectively, to sequences derived from two DC.8 cDNA clones of other haplotypes. The allelic polymorphism of DC.8 chains resides predominantly in the first extracellular domain, whereas the rest of the polypeptide is virtually constant. The exons of the DCfi gene display high homology to the corresponding exons of a murine I-Ar gene. Also, the introns show significant homology. The DCI3 chains lack eight amino acids in the cytoplasmic tail, as compared to DR and I-A .8 chains. This is probably due to a nonfunctional splice junction of DC13 genes, causing a separate cytoplasmic exon to be nonexpressed.The D region of the human major histocompatibility complex (MHC) MATERIALS AND METHODS Isolation of Genomic Clone. A genomic library was constructed from DNA donated by an HLA-homozygous human individual typed to be Dw4/DR4 (unpublished data) in the cosmid vector pHEP (12). The library was screened with a 627-basepair (bp) Ava I fragment containing almost the entire coding part of the DCP cDNA clone pII-,3l [previously denoted pDR-/3-1 (9)]. Screening of the cosmid library and growth and analysis of cosmid clones were performed as described (13), as were Southern blot analyses (14). DNA probes were labeled by nicktranslation (15).DNA Sequence Determination. Nucleotide sequences were determined with the chemical degradation procedure (16) and a modification of the dideoxy chain termination method (17) using exonuclease III and synthetic oligonucleotide primers (unpublished results). RESULTS AND DISCUSSIONIsolation of a Cosmid Containing a DCP8 Gene. Genomic DNA from a panel of DR-homozygous human individuals has been analyzed in Southern blotting experiments using a fragment from a DCB cDNA clone as probe (8). All blots with DNA digested with different enzymes show one strong constant band and one or two strong polymorphic bands. The (&chain gene of cosmid clone cosII-102 accounts for the strong polymorphic DCB bands of the genomic donor DNA. Thus, this clone was chosen for further characterization.Exon-Intron Organization of the DC.8 Gene. Two overlapping fragments containing the DC(8 gene [a 7.7-kilobase (kb) EcoRI fragment and an 11-kb BamHI fragment] were subcloned in pUC9 to facilitate sequence determination (see Fig. 1). A restriction map of the DCB gene and the sequencing strategy are shown in Fig. 1. Exons were localized by comparison with the DCB cDNA clone pII-(3-2 (unpublished results). The nucleotide sequence and the translated amino acid sequ...