Signal sequences distinguish class II histocompatibility antigen beta chains of different loci

Restriction fragment length polymorphisms of horse class II MHC genes observed using various human alpha- and beta-chain cDNA probes

Genomic DNA isolated from 20 horses was digested with up to six restriction endonucleases and subjected to southern blot hybridization analysis using various human class II alpha- and beta-chain cDNA probes. A high degree of restriction fragment length polymorphism (RFLP) was found for the DQ alpha, DP beta, DQ beta and DR beta probes, about 20 polymorphic bands being detected for each. DR alpha showed 2-4 polymorphic bands, whereas no evidence for DP alpha-like genes was found. A number of correlations of RFLPs with individual alloantisera were apparent.

1 alpha,25-dihydroxy vitamin D3 modulation of HLA-DR mRNA induced by gamma-interferon in cultured epithelial tumor cell lines

Using three cultured epithelial tumor cell lines, we investigated and analyzed the effects of gamma-interferon (gamma-IFN) and 1 alpha,25-dihydroxy vitamin D3 (1,25-(OH)2D3) on the levels of HLA-DR (alpha) mRNA and HLA-DR (beta) mRNA by Northern blot analysis. After treatment with gamma-IFN alone, the levels of the mRNA increased. Treatment with both gamma-IFN and 1,25-(OH)2D3 at the same time resulted in a significant decrease in the levels of mRNA in K-TL-1, IK-TL-2, and M-TL cells as compared to those induced by gamma-IFN alone.

A search for associations between major histocompatibility complex restriction fragment length polymorphism bands and resistance to Haemonchus contortus infection in sheep

Polymorphic bands were detected within the DQB and DRB regions of the ovine major histocompatibility complex by probing TaqI digested DNA from three large sheep half-sib families derived from a highly resistant ram. All animals were phenotypically assessed for Haemonchus contortus resistance by faecal egg counts and associations with RFLP bands and haplotypes were estimated using mixed model, best linear unbiased prediction statistical methods. Although the highly resistant sire was homozygous at the MHC, no significant associations were found between any band or haplotype and faecal egg count.

Orientation of HLA-DNA gene and identification of a CpG island-associated gene adjacent to DNA in human major histocompatibility complex class II region

We have constructed the detailed physical map of the HLA class II gene region by the pulsed field gel electrophoresis (PFGE) and cosmid walking technique. In this process, the DNA gene was found to be located telomeric to DPA1 with the 5'----3' orientation which is the same as the DPA1 and DPA2 genes, but opposite to the DQA1, DQA2 and DRA genes. This orientation is reverse to that of the counterpart gene in the rabbit major histocompatibility complex region. About 30 kb downstream from the DNA gene towards DOB, a CpG island characterized by clustered sites for rare cutting restriction enzymes and frequently associated with the 5' end of housekeeping genes was identified by PFGE and cosmid walking. From a complementary DNA (cDNA) library constructed from a Epstein-Barr virus-transformed B-cell line, a cDNA clone was isolated using the genetic probe from this CpG island. Its nucleotide sequences suggested that it represented a new non-HLA gene with a single copy which was of little genetic polymorphism and named NAT (DNA-associated transcript). Northern blot analysis showed that the NAT gene was expressed with a 4-kb transcript in all of tissues examined so far.

Gene expression (collagenase, tissue inhibitor of metalloproteinases, complement, and HLA-DR) in rheumatoid arthritis and osteoarthritis synovium. Quantitative analysis and effect of intraarticular corticosteroids

In situ hybridization was used to localize and quantify gene expression in rheumatoid arthritis (RA) and osteoarthritis (OA) synovial tissue. Collagenase, tissue inhibitor of metalloproteinases (TIMP), HLA-DR, and complement (C2 and C3) gene expression was studied in synovial tissue from 23 patients with RA, OA, or other inflammatory arthropathies. Gene expression was highly compartmentalized: Collagenase, TIMP, and C2 messenger RNA (mRNA) were localized primarily to the synovial lining layer; HLA-DR mRNA was prominent in the lining and in some sublining lymphoid aggregates; the C3 probe hybridized only to sublining lymphoid aggregates. Relative mRNA levels were quantified using computer-assisted image analysis. There was significantly more collagenase, C2, C3, and HLA-DR mRNA in RA compared with OA patients. However, TIMP mRNA levels were similar in RA and OA. Expression of collagenase, TIMP, C2, C3, and HLA-DR genes correlated with the degree of synovial inflammation. The effect of intraarticular corticosteroid injection on synovial tissue gene expression was studied using serial percutaneous synovial biopsy samples from the knees of 3 RA patients. Joints were biopsied, injected with triamcinolone, and rebiopsied 1-2 weeks later. Histologic inflammation scores were lower in posttreatment synovia. Collagenase and TIMP mRNA, although abundant in presteroid samples, were nearly undetectable in post-steroid tissues. HLA-DR mRNA levels also were significantly decreased. C2 and C3 hybridization significantly decreased in 2 of 3 patients and 1 of 3 patients, respectively. Hence, clinical response to intraarticular steroid therapy was accompanied by histologic improvement and decreased expression of genes that play a role in articular destruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon-gamma activates co-ordinate transcription of HLA-DR, DQ, and DP genes in cultured keratinocytes and requires de novo protein synthesis

The purpose of this study was to determine the effect of interferon-gamma on keratinocyte major histocompatibility complex class II gene transcription. Transformed human foreskin keratinocytes (SVK14 cells) were incubated with recombinant IFN-gamma in the presence or absence of the protein synthesis inhibitor cycloheximide. Total cellular RNA was extracted from the cells and Northern blot analysis carried out using cDNA probes for all the functional class II genes. We report that 1) there is co-ordinate activation of all the class-II genes; 2) the rate of transcription varies between gene loci after activation; and 3) de novo protein synthesis is required for IFN-gamma activation of class II transcription.

Induction of mRNA for HLA-DR beta in human keratinocytes cocultured with interferon-gamma

Explanted human keratinocytes exposed in vitro to recombinant interferon-gamma (IFN-gamma) were investigated for the appearance of mRNA for HLA-DR. Using in situ hybridization with a (35S)UTP-labelled HLA-DR beta cRNA probe, mRNA-positive cells were detected already within 6 h with maximal numbers of positive cells as well as the amount of mRNA per cell after 48 h. The corresponding protein HLA-DR, as analysed by immunoperoxidase staining, was detected on 20%-40% of the cells after 24 h and on almost all cells within 48 h. The expression of HLA-DQ and -DP antigens were always exceeded by that of HLA-DR. Whereas an increase in the concentration of IFN-gamma above 50 U/ml did not affect the maximal level of HLA-DR reactive cells, there was a fourfold increase in the frequency of cells reactive with HLA-DQ and a twofold increase for HLA-DP when the IFN-gamma concentration was raised from 50 to 500 U/ml. When IFN-gamma was withdrawn from the cultures, HLA-DR mRNA and protein synthesis ceased--indicating the continuous need for IFN-gamma to maintain the HLA-DR synthesis in keratinocytes.

Cytokine modulation of HLA-DR expression on proliferating cord blood T cells

HLA class II antigens are not expressed on resting T cells, but upon activation, their expression is readily induced on most mature T cells. T cells derived from cord blood (CB), however, remain HLA class II even when actively proliferating. To examine the reason for this deficiency, we have now tried to modulate HLA class II expression with three cytokines: interferon-gamma (IFN-gamma), tumor necrosis factor (TNF), and interleukin-1 (IL-1); all of which are known to modulate HLA class II expression in various cell types. Although CB T cells are not, in contrast to mature T cells, able to produce IFN-gamma, IFN-gamma did not have any effect on the amount of cell surface HLA-DR antigens. IL-1 was also without effect, but TNF increased the proportion of HLA-DR+ cells in both CB and adult peripheral blood (PBL)-derived T lymphoblasts. Northern blotting analysis of the HLA-DR mRNA levels revealed that in CB cells the levels were 5-6 times lower than in the PBL-derived lymphoblasts, indicating that the lower HLA-DR antigen expression in CB T cells is due to transcriptional regulation. Of the cytokines tested, only TNF had an effect on the steady-state HLA-DR mRNA levels, increasing the levels in both CB and PBL-derived T-blasts 2-3-fold.

Characterization of class II alpha genes and DLA-D region allelic associations in the dog

Human major histocompatibility complex (HLA) cDNA probes were used to analyze the restriction fragment length polymorphism (RFLP) of the alpha genes of the DLA-D region in dogs. Genomic DNA from peripheral blood leucocytes of 23 unrelated DLA-D homozygous dogs representing nine DLA-D types (defined by mixed leucocyte reaction) was digested with restriction enzymes (BamHI, EcoRI, Hind III, Pvu II, Taq I, Rsa I, Msp I, Pst I and Bgl II), separated by agarose gel electrophoresis and transferred onto Biotrace membrane. The Southern blots were successively hybridized with radiolabelled HLA cDNA probes corresponding to DQ, DP, DZ and DR alpha genes. Clear evidence was obtained for the canine homologues of DQ and DR alpha genes with simple bi- or tri-allelic polymorphism respectively. Evidence for a single, nonpolymorphic DP alpha gene was also obtained. However, the presence of a DZ alpha gene could not be clearly demonstrated in canine genomic DNA. This report extends our previous RFLP analysis documenting polymorphism of DLA class II beta genes in the same panel of homozygous typing cell dogs, and provides the basis for DLA-D genotyping at a population level. This study also characterizes the RFLP-defined preferential allelic associations across the DLA-D region in nine different homozygous typing cell specificities.

Extensive deletions and insertions in different MHC supratypes detected by pusled field gel electrophoresis

The genomic organization of the human MHC was examined in multiple examples of six different supratypes using pulsed field electrophoresis (PFGE) after digestion of genomic DNA with infrequency cutting restriction endonucleases. Differences in restriction fragment length and band intensity were shown to be specific for each supratype. Mapping of the MHC revealed that each supratype contains previously undescribed deletions and insertions between HLA B and DQ regions.

A human lymphoblastoid B line with an abnormally large MHC class II beta chain

We have examined the MHC class II beta chains in lymphoblastoid cell lines from over 200 individuals and describe one line which possesses, in addition to normal beta chains, a species of beta chain of unusually high Mr and abnormal pI which appears to be a product of the DR locus. This abnormality in Mr, detected by SDS-gel electrophoresis, was apparent only in the presence of mercaptoethanol and was shown to be due to difference in polypeptide chain length rather than to extra glycosylation.

Coexistence of an MHC chromosomal segment marked by HLA B17,BfS,C4A6,B1,DR7, and DQw9 in different ethnic groups

Previously we have shown that the supratype HLA B17 BfS C4A6 B1 DR7 (17 6 1 7) carrying a C4/Bgl II RFLP correlating with C4A6 coexists in whites and Thai/Chinese. Using conventional and PFGE/Southern blotting with class II, class III, and TNF probes as well as serologic DQ subtyping, we have extended these comparisons and now report that four examples each of white and Oriental 17 6 1 7 bear DQw9, as well as an approximately 10kb fragment hybridizing with a DR beta probe following digestion of genomic DNA with Hind III. Furthermore, Oriental and white 17 6 1 7 share a genomic insertion of some 70kb close to the class II region. These data suggest that 17 6 1 7 may mark a highly conserved chromosomal segment which provides new insights into the biology and evolution of the major histocompatibility complex.

Reduced complexity of RFLP for HLA-DR typing by the use of a DR beta 3' cDNA probe

The polymorphism of the HLA system has been defined by alloantisera, monoclonal antibodies, MLC reactivity, protein chemistry and RFLP patterns in DNA analysis. Typing for the alleles of HLA-DR at the DNA level as an additional typing technique is useful since any nucleated cell can be used. Moreover, it is not known whether the additional polymorphism found at the DNA level in an unambiguous serotype is of functional importance and thus needs to be included in HLA-DR typing. A main problem in DNA typing is the interpretation of the complex patterns in Southern blot analysis, especially in heterozygous individuals. Therefore we constructed subprobes from full length DR beta, DQ alpha and DQ beta cDNA to reduce the number of hybridizing fragments while retaining the discriminating capacity. The clearest differences among DR alleles have been found using the restriction enzyme PvuII and the subprobe containing the 3' untranslated region of the DR beta probe. Although further characterization is necessary to be able to type at the DNA level, the simplified patterns facilitate DNA typing in heterozygous individuals for a number of haplotypes. Interestingly, the number of fragments thus obtained corresponds with the number of genes described for DR1 to DRw8 haplotypes. Based upon the finding of common hybridizing patterns in DR3, DR5 and DRw6 it may be concluded that DR3, DR5 and DRw6 have been evolved from a common ancestor. For the same reason DR4, DR7 and DRw9 may have evolved in an identical way.