Susceptible and protective major histocompatibility complex class II alleles in early-onset pauciarticular juvenile chronic arthritis

Oligonucleotide typing for alleles of the MHC loci DRB1, DQA1, and DQB1 was performed in 160 patients suffering from EOPA, JCA (or JRA = juvenile rheumatoid arthritis). Allele and haplotype frequencies of the patients were compared with the data of an unrelated healthy control group consisting of 200 individuals. Analysis of frequencies shows that HLA alleles are associated not only with susceptibility to EOPA-JCA but also with protection from the disease. The presence of protection connected with certain HLA alleles was assessed using a calculation which takes into account the condition that if one allele is increased, all other alleles of the same locus must be decreased in compensation. Protection can be assumed only in cases where a given allele has an observed frequency which is significantly beyond the expected compensatory decrease. Thus a hierarchy of associations was observed in EOPA-JCA patients. The alleles of the haplotypes DRB1*11 (12)-DQA1*0501-DQB1*0301 as well as DRB1*08-DQA1*0401-DQB1*0402 were found to be associated with susceptibility to disease, whereas the alleles DRB1*07 and DQA1*0201 converge with significant protection from the disease. Whereas the association with disease susceptibility seems to depend on a sequence motif encoded in certain DQA1 alleles, protection is associated either with alleles of DRB1 or DQA1.

HLA class II genes and antibodies against recombinant U1-nRNP proteins in patients with systemic lupus erythematosus. SLE Study Group

To investigate a possible involvement of HLA-class II alleles in the genetic predisposition for the formation of anti-U1-nRNP antibody-in systemic lupus erythematosus (SLE), genomic DNA of 178 patients was typed for the DRB1, DQA1 and DQB1 alleles using a polymerase chain reaction (PCR) and non-radioactive-oligonucleotide typing. Antibodies against recombinant U1-nRNP proteins (U1-A-, U1-C- and 70K-protein) were determined by ELISA. Anti-U1-C antibody was found in 26 (14.7%), anti-U1-A in 34 (19.2%) and anti-70K in 17 (9.6%) patients. A joint occurrence was observed for these antibodies against the recombinant U1-nRNP proteins: anti-U1-C and anti-U1-A antibodies occurred together more frequently than alone and than together with anti-U1-70K antibodies. The frequency of DRB1*04 was slightly increased in the patients with anti-U1-C as compared to the patients without anti-U1-C (P < 0.05, Pcorr = n.s., RR = 2.4). The DQA1*0301 allele, which is in linkage disequilibrium with DRB1*04, is found more frequently in anti-U1-C-positive than in antibody-negative patients. The DQB1*0303 allele, detected in 12 of 176 SLE patients, was absent in the patients with any of the antibodies against the U1-nRNP proteins. All these deviations may be due to chance alone. We concluded that the presence of antibodies against recombinant U1-nRNP proteins was not significantly associated with any HLA DRB1, DQA1 and DQB1 allele in our group of SLE patients.

Human astrocytes are only partially competent antigen presenting cells. Possible implications for lesion development in multiple sclerosis

Highly purified astrocyte cultures from human embryonic brain were examined for their capacity to present antigen to human leukocyte antigen (HLA) class II compatible, cytolytic CD4+ T lymphocytes. Most astrocytes constitutively expressed HLA class I products and LFA-3 (CD58). Constitutive expression of HLA class II, LFA-1 alpha (CD11a) and ICAM-1 (CD54) was lower and varied among different cultures, while LFA-2 (CD2) was absent. IFN-gamma alone or in combination with TNF-alpha strongly enhanced expression of HLA class I, HLA-DR, -DP, -DQ, LFA-1 alpha and ICAM-1, but did not affect expression of LFA-2 (CD2) and LFA-3 (CD58). TNF-alpha alone induced only HLA class I and ICAM-1, but not HLA class II or LFA-1 alpha. Cytokine treated, but not untreated astrocytes were able to present protein (auto-)antigens to specific T lymphocyte lines. Astrocytes expressing appropriate major histocompatibility complex class II products were lysed by CD4+ T cells specific for myelin basic protein or tetanus toxoid. The lytic response was antigen dose dependent and HLA-DR restricted. It could be blocked by antibodies against HLA-DR determinants and against the adhesion molecules LFA-1 alpha and ICAM-1. In remarkable contrast to their susceptibility to T cell lysis, antigen presenting astrocytes were not only completely unable to induce T cell proliferation but even inhibited proliferation. The results indicate that, although human astrocytes have the potential to present protein antigens to CD4+ T cells, they do not induce the co-stimulatory factors required to trigger the complete T cell activation programme.

Polymorphism in the upstream regulatory region of DQA1 genes and DRB1, QAP, DQA1, and DQB1 haplotypes in the German population

Polymorphism in the URR of the MHC class II DQA1 gene defines ten different alleles named QAP. Oligotyping for the alleles of DRB1, QAP, DQA1, and DQB1 have been performed in 210 unrelated healthy controls from Germany. Moreover, 83 HTCs from the Tenth IHWS have been tested. Four point loci haplotypes (DRB1, QAP, DQA1, and DQB1) have been analyzed in the unrelated healthy population sample. Computer analysis of the linkage disequilibria leads to the conclusion that QAP alleles are in strong linkage disequilibrium with alleles either the DQA1 or the DRB1 locus. One typical ("common") haplotype was found to be associated with each DRB1 allele in the majority (86%) of the tested persons. Apart from that, 25 other less frequent ("unusual") haplotypes, with an overall frequency of 14% have been defined. Some of these "unusual" MHC class II haplotypes were found to differ only in the regulatory alleles of DQA1 (QAP alleles) while they are identical for the alleles coding for structural elements (DRB1, DQA1, and DQB1). Most of the "unusual" haplotypes were found to carry HLA-DQ6. Assuming that "unusual" (= rare) haplotypes have arisen from "common" (= frequent) haplotypes by point mutation and recombination, we propose the existence of three recombination sites in the MHC DR-DQ region: one between DRB1 and QAP, the second between QAP and DQA1, and the third between DQA1 and DQB1.

HLA class II typing in a microtitre plate format using digoxigenin-labelled amplified DNA and biotin-labelled oligonucleotide probes

We describe a new, non-radioactive microtitre plate assay for the analysis of genetic variations at the DNA level. The new method combines hybridization of oligonucleotides with PCR amplified DNA in liquid phase with detection in solid phase using an ELISA-reader. Genomic DNA is labelled with digoxigenin during PCR using a nucleotide mix containing DIG-11-2'-deoxy-uridine-5'-triphosphate (DIG-11-dUTP). The DIG labelled, amplified genomic DNA is hybridized in solution with an oligonucleotide which is labelled with one biotin at its 3'-end, using biotin-16,2',3'-dideoxy-uridine-5'-triphosphate (BIO-16-ddUTP) and DNA deoxynucleotidylexo-transferase (TdT). The hybridized complex is immobilized in a streptavidin (SA) coated microtitre plate via the biotin and detection of digoxigenin is performed using anti-digoxigenin horseradish peroxidase, fab fragments (anti-DIG-POD), and the colorimetric substrate 2,2'-Azino-di-(3-ethylbenzthiazolinsulfonat[6]) (ABTS). The resulting absorbtion of the assay is analysed in a microtitre plate reader. This method results in highly specific and sensitive hybridization signals and with the 15 oligonucleotides chosen, allows the typing of DR1-DR10.

HLA-DP/DR interaction in early onset pauciarticular juvenile chronic arthritis

We investigated the polymorphic second exon of the HLA-DPB1 and HLA-DRB1 genes, using in vitro DNA amplification by polymerase chain reaction (PCR) and oligonucleotide hybridization in 136 patients with early onset pauciarticular juvenile chronic arthritis (EOPA-JCA) and 199 healthy controls. The analysis of the HLA-DRB1 system revealed that most of the DRB1 alleles are not indifferent with respect to susceptibility to EOPA-JCA. There is a hierarchy of susceptible (DRB1*08, DR5), "permissive" (DRB1*01), moderately "protective" (DR2, DRB1*04), and "protective" (DRB1*07) alleles. In contrast, no hierarchy could be shown for the HLA-DPB1 system. DPB1*0201 was found to be susceptible. The relatively frequent alleles DPB1*0402 and DPB1*0401 seem to be indifferent. The associations with DPB1*0201, DR5, and DRB1*08 are independent of each other: that is to say they, are not brought about by linkage disequilibrium. The susceptible alleles DPB1*0201 and DR5 show evidence for interaction in the pathogenesis of EOPA-JCA. Interaction seems likely between DPB1*0201 and DRB1*08, DR5 and DRB1*08, or between DR6 and DRB1*08. The strongest interaction exists between DPB1*0201 and a common DQ factor associated with both DR5 and DRB1*08. Finally, we observed a hierarchy among the various marker combinations, where the risk of developing EOPA-JCA increases with the number of associated markers present in an individual.

Non-radioactive oligotyping for HLA-DR1-DRw10 using polymerase chain reaction, digoxigenin-labelled oligonucleotides and chemiluminescence detection

We describe a rapid non-radioactive DNA typing of the serological types DR1-DRw10 using polymerase chain reaction (PCR)-amplified DNA and 15 sequence-specific oligonucleotides (SSO) which are labelled enzymatically at their 3' end with one digoxigenin (DIG). The hybridized SSOs were detected using anti-DIG alkaline phosphatase and Fab fragments and visualization was obtained with the chemiluminescent substate 3-(2'-spiroadamantan)-4-(3''-phosphoryloxy)-phenyl-1,2-di o xetan (AMPPD). The results were identical with those of the previously used 5-bromo-4-chloro-3-indolyl-phosphate (BCIP)/4-nitrobluetetrazolium chloride (NBT) system. The use of AMPPD is more rapid and allows the repeated rehybridization of the membrane-bound DNA.

Nonradioactive HLA class II typing using polymerase chain reaction and digoxigenin-11-2'-3'-dideoxy-uridinetriphosphate-labeled oligonucleotide probes

We describe a new, simple, rapid, and sensitive nonradioactive technique for the analysis of genetic variations. Genomic DNA was amplified using polymerase chain reaction and amplified DNA was hybridized, with digoxigenin (DIG)-labeled sequence-specific oligonucleotides. High specificity and sensitivity was achieved when labeling the sequence-specific oligonucleotide at the 3' end with only one DIG using digoxigenin-11-2',3'-dideoxy-uridine-5'-triphosphate and DNA deoxynucleotidylexotransferase. The hybridized probes were detected using antidigoxigenin alkaline phosphatase, fab fragments, and X-phosphate/NBT for visualization. This method was applied to the analysis of HLA-DR4-DRB1 alleles in polymerase chain reaction-amplified genomic DNA and resulted in highly specific and sensitive hybridization signals discriminating even in cases of a one-base-pair mismatch. This technique is particularly suited for HLA oligotyping because it allows the use of tetramethylammonium chloride for the simplification of hybridization and washing conditions.