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W Verduyn

Publications and source records attributed to W Verduyn.

14 recordsLinked to original sources
PubMed1996

Six newly identified HLA-DRB alleles: DRB1*1121, *1419, *1420, *1421, DRB3*0203 and DRB5*0103.

Seven samples with irregular PCR-SSO hybridization patterns, observed during routine HLA-DRB typing, were studied in more detail. Group-specific amplification, followed by hybridization with relevant SSOs strengthened the suggestion that these samples contained new DRB alleles. DRB exon 2 segments were amplified, cloned and sequenced and revealed: DRB1*1121 [MUL] is similar to DRB1*1102 in which codon 85 changed from GTT(V) into GTC(A); DRB1*1419 [AKKAL] is similar to DRB1*1402 with codon 71 changed from AGG(R) into AAG(K); DRB1*1420 [OND-52971] is a DRB1*1406 with codon 37 changed from AAC(N) into TTC(F); DRB1*1421 [TGI] is similar to DRB1*1417 with codon 71 changed from AGG(R) into AAG(K); DRB3*0203 [POS] is similar to DRB3*0202 in which codons 37-38 are changed from TAC GCG(YA) into TCC GTC(SV); DRB5*0103 was found in two unrelated individuals of Oriental origin [IND-24 and IND-59] and is similar to DRB5*0102 in which codon 71 AGG(R) changed into ACG(T). This particular sequence variation at position 71 has not yet been described. The new DRB sequences were confirmed using the sequencing based typing technique. Low resolution PCR-SSP typing failed to amplify two of the DRB1*14 variants, whereas high resolution PCR-SSP resulted in aberrant patterns. Class II alloantisera identify the codon 71 changes in DRB1*1419 and *1421 with respect to the MC1 ('DR1+DR4') epitope.

Alleles↗
PubMed1996

HLA-DRB1*04 high resolution typing.

High resolution typing for HLA-DR4 is required to identify the individual subtypes. In this study a panel of DR4-positive samples was typed by both sequencing-based typing (SBT) and oligohybridization (PCR sequence-specific oligonucleotide; PCR-SSO). SBT reveals the highest resolution; moreover, ambiguous DRB1*04 allelic combinations can be resolved by a selective amplification of the individual alleles and subsequent sequencing. An extended DR4-specific PCR-SSO makes high resolution typing possible; however, an additional protocol is required to resolve ambiguities.

Alleles↗
PubMed1995

Irregular polymerase chain reaction-sequence-specific oligonucleotide hybridization patterns reveal seven new HLA-DRB1 alleles related to DR2, DR3, DR6, DR8, and DR11. Implications for sequence-specific priming.

In the past 3 years we have typed over 7000 individuals for HLA-DRB using a nonradioactive PCR-SSO method. The use of locally developed computer programs simplified data input and the interpretation of the DRB PCR-SSO readings. In this way we detected a number of samples with unexpected hybridization patterns. DRB1 exon 2 segments of these samples were amplified, cloned, and sequenced and appeared to identify seven new DRB alleles: DRB1*0304, a DRB1*0301 variant, was observed in three unrelated Caucasoid individuals; DRB1*1606, which is very similar to *1603; DRB1*1113 is a *1101 variant with some *1401 sequences; DRB1*1310 is *1301-like; DRB1*1311 is similar to *1305 and *1307; DRB1*1416 is a *1401 sequence with a HV3 derived from *1301; DRB1*0808 was found in an Ethiopian individual. Next, we studied the effectiveness of PCR-SSP typing of the newly defined DRB1 alleles. Only two variants were distinguished as odd by PCR-SSP and two were typed as regular specificities. Three alleles were not amplified by the primer sets used. As compared to PCR-SSO, the PCR-SSP typing method using currently available typing kits clearly has limitations as far as the recognition of new and variant alleles is concerned. The products of some of these new alleles may be distinguished using conventional serology.

Alleles↗
PubMed1995

Novel HLA-DPB1 alleles detected in the Ethiopian population.

The number of identified HLA-DPB1 alleles increased rapidly by application of DNA-based typing techniques. PCR-SSO typing indicated the presence of possible new HLA-DPB1 variants in the Ethiopian population. The use of the SBT technique, which considers polymorphic as well as constant regions in the second exon of HLA genes, allowed direct identification of two new allelic variants. Moreover, a recently identified HLA-DPA1 variant was also present in this population. The newly defined allelic HLA-DPB1 sequences found in five individuals of the Ethiopian population were confirmed by cloning and subsequent sequencing of the cloned DNA. One of the new alleles was shown to segregate in a family and was also present in unrelated individuals. Both new DPB1 alleles represent new combinations of existing polymorphism in the hypervariable regions. In different populations the frequency of these new HLA-DP variants remains to be determined.

Alleles↗
PubMed1993

Biotinylated DRB sequence-specific oligonucleotides. Comparison to serologic HLA-DR typing of organ donors in eurotransplant.

A novel HLA-DR typing method was applied using PCR-amplified fragments and biotin-labeled oligonucleotides (PCR-biotin-SSO). The PCR-biotin-SSO method can be used efficiently to perform HLA-DR typing for a large number of individuals when time is not the limiting factor. The reliability of HLA typing of cadaveric organ donors is of vital importance for organ exchange organizations such as ET. Due to lack of time, these typings are usually performed by the complement-dependent cytotoxicity. The individual donor center typings are immediately reported to ET, where the recipient selection procedure is started. DNA isolated from donor spleen material, sent to the ETRL for retyping purposes, was subjected to PCR-biotin-SSO typing. The results were compared with the serological HLA-DR typings as reported to ET. The analysis of 1052 donor samples for the broad DR1-DR10 antigens revealed a concordance rate of over 90% between the donor center and the ETRL. The majority of the discrepancies involved specificities of the HLA-DR5, DR6, and DR8 cross-reacting group, with DR6 as the predominant discordant specificity. The results indicate (a) that PCR-biotin-SSO is a reliable technique for DNA-based HLA-DR typing and (b) that HLA-DR serology is still a useful technique when time is limited, such as for cadaveric donor typing.

Base Sequence↗
PubMed1992

Relative contribution of HLA-DQA and -DQB alleles to predisposition to insulin-dependent diabetes mellitus.

The presence of DQA and DQB alleles conferring protection or susceptibility was assessed in a panel of 39 insulin-dependent diabetes mellitus patients and 39 healthy control subjects from the central highland of Ethiopia. The results were grouped into three entities: a combination of alleles conferring susceptibility, a group conferring protection, and a group without any apparent HLA-DQ or -DR predisposition to insulin-dependent (type 1) diabetes mellitus (IDDM). Statistical analysis revealed that the relative risk of the first group is 64.1. If a similar approach is applied to the data on a study in caucasoid IDDM patients and controls of Kahlil and colleagues, the pattern is fully consistent with the data presented here, with an extraordinarily high relative risk (RR 258.2). It will be of interest to study whether this subdivision is reflected or supported by clinical or etiologic differences of the disease. The predictive value of susceptibility phenotypes appears to be more accurate by the proposed subdivision. Furthermore, in combination with islet-cell antibody analysis, assessment of genotype will permit more accurate identification of prediabetic individuals to be entered in clinical trials.

Alleles↗
PubMed1992

T-cell recognition of class II products that result from the combined presence of two different HLA haplotypes.

To analyze DR2 haplotypes as recognized by alloreactive T cells, lymphocytes from a DR7; DQw2 homozygous donor were cocultured with irradiated lymphocytes that were DRw15, DR7; DQw6, DQw2 heterozygous. In this report, we focus on two HLA-DQ-specific T-cell clones obtained from this priming. These two clones (c3518 and c3523) responded to the positive control (original stimulator) and five of 66 panel donors. Three of these donors typed DRw15, DR7; DQw6, DQw2, as did the positive control. One stimulatory donor typed DRw15, DR7; DQw6, DQw9 and one stimulatory donor typed DRw14, DR7; DQw5, DQw2. Oligonucleotide typing revealed that recognition by the clones depended on the simultaneous presence of the DQB1*0602 gene on one haplotype and DRB1*0701 or DQA*0201 on the other. The hypothesis that c3518 and c3523 recognize an HLA class II product that results from the combination of two different HLA haplotypes was further confirmed in family studies. In three families, it was shown that the DRw15, DR7; DQw6, (DQw2 or DQw9)-positive individuals were recognized, whereas the cells carrying either DRw15; DQw6, DR7; DQw2, or DR7; DQw9 were nonstimulatory. Our results can be explained in two ways: (a) the T cells recognize a class II dimer that results from trans-complementation of DQA1*0101 and DQB1*0602, and (2) the T cells recognize a DR7-derived peptide that is presented by DQw6.

Antibodies, Monoclonal↗
PubMed1991

Oligonucleotide typing is a perfect tool to identify antigens stimulatory in the mixed lymphocyte culture.

An important criterion for the selection of donors for bone marrow transplantation is the grade of matching for HLA between donor and recipient. For patients that lack an HLA-identical sibling, an extending pool of unrelated volunteers for bone marrow donation is available. From these donors the best matched candidate can be selected by serological typing, followed by a mixed lymphocyte culture (MLC). Oligonucleotide genotyping for HLA class II antigens is considered to be valuable for the prediction of MLC reactivity. We investigated whether this typing method, in combination with serological typing, would cover the recognition of all MLC stimulatory determinants. One hundred thirty-six combinations of HLA-A, -B, and -DR serologically identical individuals were tested in the MLC. Additional typing for HLA-DRB and HLA-DPB by oligonucleotide genotyping made it possible to evaluate the influence of these genes on MLC reactivity. Combinations that were matched for HLA-DRB gave significantly lower responses than those that were mismatched. Nevertheless, in the matched combinations responses were observed to 94% relative response index. These responses could all be attributed to HLA-DP, since all combinations that were identical by HLA-DPB genotyping were negative in the MLC. In conclusion, with the combined use of serology and oligonucleotide genotyping, responder-stimulator combinations can be selected that are identical for all MLC stimulatory determinants.

Bone Marrow Transplantation↗
PubMed1991

Increasing complexity of HLA-DR2 as detected by serology and oligonucleotide typing.

Serological and oligonucleotide typing was performed on a number of HLA-DR2-positive cells from different ethnic origin, including DR2 haplotypes with various DQ associations. Exons 2 of DRB1 and DRB5 of DR2-positive individuals were locus-specific amplified and hybridized with a number of different oligonucleotides capable of discriminating between the various Dw2, Dw12, Dw21, and Dw22 associated sequences. The linkage of DRB with DQA1 and DQB1 in these haplotypes was analyzed. Among the DR2- positive cells we could define 10 different DR DQ haplotypes by serology and 13 by oligonucleotide typing. The DR2.ES specificity is a serological DRw15 variant which could not be discriminated by oligonucleotide typing from a DRw15 DQw5 haplotype. The DR2.JA variant represents a unique DRB1*1602 DRB5*0101 haplotype. The DR1+2s haplotype consists of a DRB1 DQ region from a Dw1 and a DRB5 gene from a Dw2 haplotype. Its short DR2 serum pattern can be explained by the absence of a DR2 DRB1 gene product. DRB5*0101 sequences were found in association with DRB1*1501, *1502, *1602, and *0101 alleles. Since the DRB5 gene is capable of such different associations it is comparable to the DRB3 and DRB4 genes. This may have implications for the definition of the broad DR2 specificity which is predominantly encoded by the DRB5 gene product. New DR2 haplotypes included the following DQ combinations: DQw2-positive DQA1/B1*0301/0201 and DQw6-positive DQA1/B1*0102/0601 and *0102/0603 haplotypes.

Amino Acid Sequence↗
PubMed1986

The interaction between gamma-type endorphins and HLA class I antigens.

The clinical response of schizophrenic patients to treatment with gamma-type endorphins was found to be associated with certain HLA class I antigens (Bw22, B15, B13). Moreover, pretreatment of lymphocytes from healthy donors with des-Tyr1-gamma-endorphin (DT gamma E) inhibits the complement-dependent cytotoxicity between alloantisera and those HLA antigens, of which the frequency was increased among schizophrenic patients, who respond well to the gamma-endorphin therapy. Also for the opiate antagonist, naloxon interactions with HLA class I antigens could be demonstrated. Using the inhibition assay with DT gamma E it was possible to detect a subtype of HLA-A2, which, until now, was only defined by cytotoxic T lymphocytes and biochemistry. These data suggest an interaction between the HLA class I antigens and the receptor(s) for DT gamma E and naloxon, which may support the hypothesis that HLA class I antigens play a role in many recognition processes. Their role in immunological recognition would then be only a specialized form of a more general function.

Antigen-Antibody Reactions↗