SB-restricted presentation of influenza and herpes simplex virus antigens to human T-lymphocyte clones

Differences in Expression of Human Leukocyte Antigen Class II Subtypes and T Cell Subsets in Behçet's Disease with Arthritis

It has been reported Human Leukocyte Antigen (HLA) gene polymorphism is a risk factor for the development of Behçet’s disease (BD). In this study, the association of HLA class II subtypes HLA-DP, DQ, DR, and T cell subsets in BD patients with arthritis was evaluated. Frequencies of HLA-DP, DQ, DR positive cells, and T cell subsets in peripheral blood leukocytes (PBL) were measured by flow cytometric analysis in BD, and compared to rheumatoid arthritis as disease controls and healthy controls. Frequencies of HLA-DQ were significantly decreased in whole PBL and granulocytes of BD active patients as compared to healthy controls. In monocytes populations, proportions of HLA-DR positive cells were significantly increased in BD active patients as compared to healthy controls. Proportions of CD4+CCR7+ and CD8+CCR7+ cells were significantly higher in BD active patients than in BD inactive in whole PBL. Frequencies of CD4+CD62L- and CD8+CD62L- cells in lymphocytes were significantly decreased in active BD than those in inactive BD. There were also correlations between disease activity markers and T cell subsets. Our results revealed HLA-DP, DQ, and DR expressing cell frequencies and several T cell subsets were significantly correlated with BD arthritis symptoms.

HLA-DP, HLA-DQ, and HLA-DR have different requirements for invariant chain and HLA-DM

The MHC is central to the adaptive immune response. The human MHC class II is encoded by three different isotypes, HLA-DR, -DQ, and -DP, each being highly polymorphic. In contrast to HLA-DR, the intracellular assembly and trafficking of HLA-DP molecules have not been studied extensively. However, different HLA-DP variants can be either protective or risk factors for infectious diseases (e.g. hepatitis B), immune dysfunction (e.g. berylliosis), and autoimmunity (e.g. myasthenia gravis). Here, we establish a system to analyze the chaperone requirements for HLA-DP and to compare the assembly and trafficking of HLA-DP, -DQ, and -DR directly. Unlike HLA-DR1, HLA-DQ5 and HLA-DP4 can form SDS-stable dimers supported by invariant chain (Ii) in the absence of HLA-DM. Uniquely, HLA-DP also forms dimers in the presence of HLA-DM alone. In model antigen-presenting cells, SDS-stable HLA-DP complexes are resistant to treatments that prevent formation of SDS-stable HLA-DR complexes. The unexpected properties of HLA-DP molecules may help explain why they bind to a more restricted range of peptides than other human MHC class II proteins and frequently present viral peptides.

Importance of HLA-DQ and HLA-DP polymorphisms in cytokine responses to naturally processed HLA-DR-derived measles virus peptides

We studied the association between class II human leukocyte antigen (HLA)-DRB1*0301 presented measles virus (MV) peptide-specific cytokine responses and DQB1 and DPB1 alleles among 313 individuals who received two doses of measles-mumps-rubella-II vaccine. The overall median IFN-gamma secretion levels (first and third quartiles) for the 19-amino acid MV phosphoprotein (MV-P)- and 14-amino acid MV nucleoprotein (MV-N)-derived peptides were 27.7 pg/ml (1.8, 109.4) and 1.9 pg/ml (-6.2, 13.0), respectively; median IL-4 secretion levels were -0.6 pg/ml (-7.1, 6.2) and 2.4 pg/ml (-3.2, 9.3), respectively. Primary statistical analyses were adjusted for previously identified DRB1 associations. A marginally significant increase in the frequency of the DQB1*0604 (p=0.02) allele was found among subjects who demonstrated detectable IL-4 levels to the MV-P peptide. Further, DPB1*0201 (p=0.02) and DPB1*1301 (p=0.09) alleles provided suggestive evidence of an association with MV-P-induced IL-4 secretion. Examination of IFN-gamma responses to MV-P and MV-N indicated that none of the individual alleles of the DQB1 and DPB1 loci were associated with peptide-induced T cell response. An increase in the frequency of DPB1*0501 (p=0.01) was found among subjects who failed to produce MV-N peptide-specific IL-4 responses. These data further confirm that HLA-DRB1 alleles are the major restriction molecules for MV-P and MV-N measles virus antigen presentation to T cells. We speculate that MV-P and MV-N peptides derived from DRB1*0301 could potentially be recognized in association with different HLA molecules, including DQB1 and DPB1; however, statistical adjustments for the effect of HLA-DR locus could potentially alter these genetic relationships. This concept provides important information supporting the use of promiscuous peptides in a peptide-based vaccine approach.

HLA-DPB1 matching status has significant implications for recipients of unrelated donor stem cell transplants

Studies in unrelated donor (UD) hematopoietic stem cell transplantations (HSCT) show an effect of the matching status of HLA-DPB1 on complications. We analyzed 423 UD-HSCT pairs. Most protocols included T-cell depletion (TCD). All pairs had high-resolution tissue typing performed for 6 HLA loci. Two hundred eighty-two pairs were matched at 10 of 10 alleles (29% were DPB1 matched). In 141 HLA-mismatched pairs, 28% were matched for DPB1. In the 10 of 10 matched pairs (n = 282), the 3-year probability of relapse was 61%. This was significantly higher in DPB1-matched pairs (74%) as compared with DPB1-mismatched pairs (56%) (log rank, P = .001). This finding persisted in multivariate analysis. In the group overall (n = 423), relapse was also significantly increased if DPB1 was matched (log rank; P < .001). These results were similar in chronic myeloid leukemia (CML; P < .001) and acute lymphoblastic leukemia (ALL; P = .013). In ALL, DPB1-matched pairs had a significantly worse overall survival (log rank; P = .025). Thus, in recipients of TCD UD-HSCT, a match for DPB1 is associated with a significantly increased risk of disease relapse, irrespective of the matching status for the other HLA molecules. It is possible that this effect is especially apparent following TCD transplantations and invites speculation about the function of DPB1 within the immune system.

HLA-DP4 presents an immunodominant peptide from the RSV G protein to CD4 T cells

CD4 T cells play a crucial role during virus infections by producing antiviral cytokines and by regulating humoral and cellular immune responses. Unfortunately however, exaggerated CD4 T cell responses can cause significant immune-mediated disease as was observed during RSV infections in children previously vaccinated with a formalin-inactivated virus in the 1960s. It has been observed that vaccination with the G protein of RSV tends to prime mice for a similar Th2-mediated enhanced disease. Whether the G protein may play a role in enhanced disease in man is unclear. In the present study, we identified an immunodominant epitope in the conserved region of the G protein encompassing amino acid residues 162-175. This epitope is presented in the context of HLA-DPB1*0401 and DPB1*0402, the most prevalent HLA class II alleles. Importantly, in some patients, a mixed Th1/Th2 response against this epitope was found in bronchoalveolar lavage samples during primary RSV infections.

Roles of HLA-B, HLA-C and HLA-DPA1 incompatibilities in the outcome of unrelated stem-cell transplantation

In unrelated stem-cell transplantation, the value of matching at the HLA-A, -B and -DR loci between donor and recipient is well documented. The effect of HLA-C, DPB1 and DPA1 mismatches on transplantation outcome is unclear. In this study, 104 donor recipient-pairs, transplanted at Huddinge University Hospital between 1988 and 1999, were retrospectively HLA class I- and class II-typed by PCR-SSP. The samples were typed for HLA-A, -B and -C and HLA-DRB1, -DRB3, -DRB4, -DRB5, -DQA1, -DQB1, -DPB1 and -DPA1 with allele level resolution. Isolated HLA-B allele level mismatches were associated with an increased incidence of acute graft versus host disease grades II-IV and grades III-IV. HLA-C-mismatched, but killer cell immunoglobulin-like receptor (KIR) ligand motif-matched stem-cell grafts were significantly associated with improved survival rates and relapse-free survival (RFS). In patients receiving HLA-DPA1-mismatched stem cell grafts, reduced survival and shorter RFS were seen. These patients also had an increased frequency of relapses (64%vs 26%). We conclude that genomic HLA class I- and class II-typing may improve the outcome after unrelated stem-cell transplantation. The awareness of HLA class I- and II-mismatches in a recipient-donor pair makes it possible to give appropriate pre- and post-transplantation treatment.

Identification of an association between HLA class II alleles and low antibody levels after measles immunization

This is the first large cohort study to report a genetic association between humoral antibody level after measles vaccine and the HLA class II genes. The WHO goal to eradicate measles world-wide magnifies the importance of data relating to the influence of immunogenetics on measles vaccine-induced antibody responses. We present here the analysis of 242 individuals who received one dose of measles-mumps-rubella-II (MMR-II) vaccine at the age of 15 months and were genotyped for HLA class II alleles. These subjects fit into one of three categories; 72 were classified as seronegative, 93 were seropositive and 77 were serohyperpositive. HLA-DRB1*03 (odds ratio (OR), 2.22) and HLA-DPA1*0201 (OR, 1.71) were significantly associated with measles vaccine seronegativity, while additional alleles provided suggestive evidence of association with seronegativity: DQA1*0201, DQB1*0201, and DQA1*0501. The alleles DRB1*03 and DQA1*0201 remained statistically significant after accounting for the effects of other alleles. These findings are crucial in designing both measles eradication by the use of vaccine, and future vaccines to be used in genetically heterozygous populations.

HLA-DPB1 typing by polymerase chain reaction amplification with sequence-specific primers

DPB1 is the second most polymorphic class II locus with currently 84 recognized alleles, i.e. DPB1*0101 to DPB1*8101. Most of the alleles have been described during the last few years using oligonucleotide and sequencing techniques and relatively little is known about the role and importance of the polymorphic residues as regards to the function of DP molecules. In the present study, polymerase chain reaction (PCR) primers were designed for identification of all the phenotypically different DPB1 alleles by PCR amplification with sequence-specific primers. Forty-eight standard genomic PCR reactions per sample were performed in order to achieve this resolution. Unique amplification patterns were obtained in 2983 of 3160 (94.4%) possible genotypes. The primers were combined so that only very rare genotypes gave rise to ambiguous patterns. Sixty-four Histocompatibility Workshop cell lines and 150 DNAs provided by the UCLA DNA exchange were investigated by the DPB1 primer set. All typing results were conclusive. Analysis of the distribution of DPB1 alleles was performed in 200 Caucasian samples, 100 African samples and 40 Oriental samples. The population study by the DPB1 PCR-SSP method showed a characteristic distribution of HLA-DPB1 alleles. Each ethnic group had one, or two, frequent DPB1 allele(s) and the frequency of homozygotes was high, suggesting that balancing selection does not appear to be affecting the evolution of the DPB1 locus.

Definition of five new simian immunodeficiency virus cytotoxic T-lymphocyte epitopes and their restricting major histocompatibility complex class I molecules: evidence for an influence on disease progression

Simian immunodeficiency virus (SIV) infection of the rhesus macaque is currently the best animal model for AIDS vaccine development. One limitation of this model, however, has been the small number of cytotoxic T-lymphocyte (CTL) epitopes and restricting major histocompatibility complex (MHC) class I molecules available for investigating virus-specific CTL responses. To identify new MHC class I-restricted CTL epitopes, we infected five members of a family of MHC-defined rhesus macaques intravenously with SIV. Five new CTL epitopes bound by four different MHC class I molecules were defined. These included two Env epitopes bound by Mamu-A*11 and -B*03 and three Nef epitopes bound by Mamu-B*03, -B*04, and -B*17. All four restricting MHC class I molecules were encoded on only two haplotypes (b or c). Interestingly, resistance to disease progression within this family appeared to be associated with the inheritance of one or both of these MHC class I haplotypes. Two individuals that inherited haplotypes b and c separately survived for 299 and 511 days, respectively, while another individual that inherited both haplotypes survived for 889 days. In contrast, two MHC class I-identical individuals that did not inherit either haplotype rapidly progressed to disease (survived <80 days). Since all five offspring were identical at their Mamu-DRB loci, MHC class II differences are unlikely to account for their patterns of disease progression. These results double the number of SIV CTL epitopes defined in rhesus macaques and provide evidence that allelic differences at the MHC class I loci may influence rates of disease progression among AIDS virus-infected individuals.

IgE production after antigen-specific and cognate activation of HLA-DPw4-restricted T-cell clones, by 78% of randomly selected B-cell donors

The frequency of expression of the MHC class II antigen, HLA-DPw4, in the caucasoid population is approximately 78%, and is unmatched by phenotypic frequencies of other HLA class II molecules. Here we describe three human Der-P1-specific T-cell clones (TCC), restricted by the HLA-DPw4-variant HLA-DPB1*0401, of which two TCC also responded to antigen, presented on HLA-DPB1*0402. Thus, randomly selected caucasoid donors present a 78% chance for a correct match with these HLA-DPw4-restricted TCC. This allows comparative in vitro antigen presentation studies with various antigen presenting cells (APC) from different (healthy or diseased) donors without the variable influence of responding T cells. It was subsequently demonstrated that the TCC can be used to study antigen-induced IgE production in randomly selected primary B cells. Cognate HLA-DPw4-restricted antigen presentation caused enhanced immunoglobulin production of IgE, IgG1, IgA and IgM, of which only IgE induction was reversed by addition of anti-IL-4 antibodies.

HLA class II DRB1, DQB1, DPB1 polymorphism and cardiomyopathy due to Trypanosoma cruzi chronic infection

Trypanosomiasis is an important cause of cardiomyopathy in endemic rural areas of Latin America. Previous studies have suggested participation of HLA molecules in the immune response regulation of T. cruzi infection, and association of HLA antigens with heart damage. One hundred and eleven unrelated T. cruzi antigen-seropositive individuals were tested for HLA class II alleles by the polymerase chain reaction and sequence specific oligonucleotide (PCR-SSO) method. Patients were classified in 3 groups according to clinical and electrocardiographic characteristics: asymptomatics (group A), with arrhythmia (group B), and with overt congestive heart failure (group C). Statistical analysis confirmed the significant increment of the DRB1*01 DQB1*0501 haplotype (p = 0.03) previously reported by our laboratory in patients with cardiomyopathy. The DPB1*0401 allele frequency is also significantly increased in patients with heart disease (groups B + C) (p = 0.009) while DPB1*0101 frequency is higher among the asymptomatic group (p = 0.04) compared with individuals of group C. The DPB1*0401 allele in homozygous form or in combination with allele DPB1*2301 or 3901, was found present more often in patients of groups B and C. Thus, the combination of two of these three alleles, sharing specific sequence motifs in positions 8, 9, 76, and 84-87 confers a relative risk of 6.55 to develop cardiomyopathy in seropositive patients (p = 0.041). Furthermore, 32% of the cardiomyopathics have either DRB1*01 DQB1*0501 and/or DPB1*0401/*0401, 0401/*2301, or* 0401/*3901 compared with 9% of the seropositive asymptomatics (OR = 5.0; p = 0.006).

Application of RSCA for the typing of HLA-DPB1

We describe the application of RSCA, for the high resolution typing of alleles encoded at the HLA-DPB1 locus. RSCA differs from other sequence based typing methodologies in that the HLA type is assigned on the basis of differences in DNA conformation between different alleles. A total of 251 samples were typed in a blind study, of these 109 samples had been typed previously by conventional techniques. A comparison of the RSCA data with the historical typing results showed a concordance over 93%. Seven samples initially had discordant results, however, when these samples were typed by direct sequencing, the type assigned by RSCA was found to be correct in all but one case, indicating a concordance over 99%. RSCA has proved to be a simple reliable technique for the typing of the HLA-DPB1 locus, and is not limited by the ambiguous combinations of alleles determined in other conventional techniques.

Characterization and distribution of Mhc-DPB1 alleles in chimpanzee and rhesus macaque populations

Allelic diversity at the nonhuman primate Mhc-DPB1 locus was studied by determining exon 2 nucleotide sequences. This resulted in the detection of 17 chimpanzee (Pan troglodytes), 2 orangutan (Pongo pygmaeus) and 16 rhesus macaque (Macaca mulatta) alleles. These were compiled with primate Mhc-DPB1 nucleotide sequences that were published previously. Based upon the results, a sequence specific oligotyping method was developed allowing us to investigate the distribution of Mhc-DPB1 alleles in distinct chimpanzee and rhesus macaque colonies. Like found in humans, chimpanzee and rhesus macaque populations originating from different geographic backgrounds appear to be characterized by the presence of a few dominant Mhc-DPB1 alleles.

HLA DPA1/DPB1 genotype and haplotype frequencies, and linkage disequilibria in Nigeria, Liberia, and Gabon

The frequencies of DPA1 and DPB1 alleles and their occurrence in haplotypic linkage were assessed and compared in Nigerian, Liberian, and Gabonese individuals. Differences were seen in the distribution patterns; these differences were more pronounced between the Gabonese and the other two populations than between Liberians and Nigerians. Several haplotypic DPA1-DPB1 combinations could be verified by homozygosity. Linkage disequilibria of DPA1-DPB1 combinations, indicating further probable haplotypes, were estimated. Although different allele and haplotype frequencies were recognized in the three subgroups, the linkage disequilibria were mostly either positive or negative in all populations.

Comprehensive HLA-DP typing using polymerase chain reaction with sequence-specific primers and 95 sequence-specific primer mixes

HLA-DP is the third of the class II molecules. Its role is antigen presentation, and it has been suggested to play a part in the susceptibility to certain diseases such as berylliosis, sarcoidosis and juvenile chronic arthritis. The standard typing method is SSO typing, although other methods have been used. Probably the best is sequence-based typing, but this is time-consuming and requires expensive equipment. We describe a method for comprehensive HLA-DPB1 and HLA-DPA1 typing using sequence-specific primers. This method has the advantages that it is rapid - typing a single DNA sample takes under 3 hours - and does not require any special equipment or reagents. The method has been shown to be highly accurate by typing 60 cell line DNA samples in which there was 100% agreement between the types obtained and the published information. Similarly typing of 20 DNA samples previously typed by sequence-based typing gave 100% concordance. We used the method to type DNA samples from 102 UK Caucasoid kidney donors. The allele frequencies agree with previously published data. Linkage disequilibria between HLA-DPB1, HLA-DPA1 and the other class II antigens have been investigated. Strong linkage disequilibria exist between certain HLA-DPB1 and HLA-DPA1 alleles. This is unsurprising in view of their proximity on the chromosome. More unexpectedly, the data also suggest that genes further away along the chromosome are in linkage disequilibrium with HLA-DP, forming extended haplotypes.

Effect of polymorphism of the HLA-DPA1 chain on presentation of antigenic peptides

Human T-cell clones that recognize a peptide from mycobacterial heat shock protein 60 in the context of HLA-DP were found to be sensitive to changes in the DPA1 chain of the restricting element, optimal responses being seen with the combination HLA-DPA1*0201 and HLA-DPB*0301. HLA-DP dimers containing HLA-DPA1*01 were only able to present antigenic peptides to T-cell clones when peptides were present throughout the period of coculture of T cells with antigen presenting cells. In contrast the optimal HLA-DP dimer could also stimulate T-cell clones maximally when incubated with peptides for 1 h and then thoroughly washed. This suggests that the DPA1 polymorphism influenced the strength of binding of antigenic peptides to the HLA-DP dimer. Modeling studies identified amino acid 31 of DPA1 as the polymorphic residue most likely to account for this effect. This is the first demonstration that the relatively limited polymorphism displayed by DPA1 has functional consequences.

HLA-DPA1 typing by PCR amplification with sequence-specific primers (PCR-SSP) and distribution of DPA1 alleles in Caucasian, African and Oriental populations

In the present study PCR primers were designed for detecting all known DPA1 variability, i.e., the presently recognized six DPA1 alleles 0103 to 0401, and also for separation of the four DPA1*02 alleles, by PCR amplification with sequence-specific primers (PCR-SSP). For each sample seven different PCR reactions were performed which allowed the identification of all DPA1 alleles and the resolution of all DPA1 genotypes. Forty-eight cell lines and 100 donor spleen cells were investigated by the DPA1 PCR-SSP technique. In the forty-eight known workshop cell-lines no false positive or false negative results were obtained. The 100 donor spleen cells were only typed by the PCR-SSP technique and in their DNAs only one or two DPA1 alleles were found. Twenty cell lines and twenty donor spleen cells were typed on two separate occasions and interpreted blindly. The reproducibility between the repeated typings was 100%. The length of the specific products ranged from 103 to 258 base pairs and the amplification patterns obtained were easy to interpret. In conclusion, DPA1 typing by the PCR-SSP method is an accurate typing technique with high sensitivity, specificity and reproducibility. Analysis of the distribution of DPA1 alleles was performed in 100 Caucasian samples, 100 African samples and 80 Oriental samples, including separation of the four of HLA-DPA1 alleles. Each ethnic group appeared to have one (Caucasians), or two (Africans and Orientals), frequent DPA1 allele(s) and a high frequency of DPA1 homozygotes, suggesting that, like for the DPB1 locus, balancing selection does not appear to be affecting the evolution of the DPA1 locus.

Cis-diamminedichloroplatinum(II) augments expression of tumor-associated antigens on human gastric cancer cell line KATO-3 and increases susceptibility and binding of tumor cells to various cytotoxic effector cells

Previous studies have demonstrated the immunomodulatory effects of cisplatin under certain conditions. The present study was designed to clarify whether cisplatin modulates the expression of surface antigens, especially human leukocyte antigen (HLA), on human tumor cell lines and/or augments the susceptibility and binding of tumor cells to cytotoxic effector cells. A human gastric cancer cell line, KATO-3, was employed. The expression of HLA and other tumor-associated antigens was analyzed by flow cytometry using FITC-conjugated monoclonal antibodies. The cytotoxicity of effector cells was determined by 51Cr release assay. The expression of HLA class I antigen, beta2-microglobulin, leukocyte function-associated antigen-1, and AC-81 adenocarcinoma-associated antigen on KATO-3 increased after exposure to cisplatin at 10 micrograms/ml for 3-6 hr; augmentation of HLA class I subtypes -B2 and -B27 was particularly prominent. Furthermore, the susceptibility and binding of KATO-3 to both lymphokine-activated killer cells and KATO-3-specific cytotoxic T lymphocytes significantly increased after cisplatin treatment. Cisplatin may modulate the expression of tumor-associated antigens on some human tumor cells. Tumor regression by cisplatin administration may depend on its direct cytotoxicity as well as on its modulating effects on the expression of tumor-associated antigens, subsequently leading to the activation of the immune surveillance system against the tumor.

The presence of the HLA class II allele DPB1*0501 in ethnic Thais correlates with an enhanced vaccine-induced antibody response to a malaria sporozoite antigen

In this study, we examined the correlation between the frequency of allelic variants of the class II human leukocyte antigen (HLA) DR, DQ and DP gene loci and the quantitative humoral immune response observed in 71 Thai volunteers, subsequent to vaccination with a conjugated subunit vaccine. This vaccine was designed to induce antibodies directed against the immunodominant repeat region of the Plasmodium falciparum circumsporozoite (CS) protein. The presence of the DPB1*0501, a relatively common allele in Asian populations, was found to be associated with high vaccine-induced CS repeat-specific antibody responses in the volunteers. Given the increasing focus on the use of subunit vaccines in the control of infectious diseases, consideration of the influence of class II allele frequencies in ethnically diverse recipient populations may be important.

Allelic diversity at the Mhc-DP locus in rhesus macaques (Macaca mulatta)

Allelic diversity at the major histocompatibility complex class II DP locus of rhesus macaques was studied by sequencing exon 2 of Mamu-DPA1 and -DPB1 genes. The Mamu-DPA1 gene is apparently invariant, whereas the Mamu-DPB1 locus displays polymorphism. Here we report the characterization of 1 Mamu-DPA1 and 13 Mamu-DPB1 alleles which were compared with other available primate Mhc-DPA1 and -DPB1 sequences. As compared with Mhc-DRB and -DQB1, most codons for the contact residues in the antigen binding site of the primate Mhc-DPB1 gene have a relatively low degree of variation in encoding various types of amino acids. In contrast to Mhc-DRB and -DQB, the HLA- and Mamu-DPB1 sequences cluster in a species-specific manner in phylogenetic trees. Mhc-DPB1 polymorphisms, however, are inherited in a transspecies mode of evolution, as is demonstrated by the sharing of lineage members between closely related macaque species. The data demonstrate that the transspecies character of Mhc-DPB1 polymorphism was retained over much shorter periods of time as compared with its sister class II loci, Mhc-DQ and -DR.

HLA-DPB1 DNA polymorphism in the Swiss population: linkage disequilibrium with other HLA loci and population genetic affinities

Allelic diversity at the HLA-DPB1 locus was determined by PCR-oligotyping in a sample of 125 healthy Swiss individuals. A total of 17 alleles were detected among which four main alleles (DPB1*0401, *0201, *0301, *0402) reached a cumulative frequency of 74.8%. HLA-A and -B (by serology) and HLA-DRB1 (by oligotyping) allelic polymorphisms were analysed also. HLA-B and HLA-DRB1 loci were highly polymorphic with 25 and 28 alleles respectively and similar heterozygosity levels of 0.93 and 0.92. These two loci were found to be more polymorphic than expected under neutrality, while lower heterozygosity levels were found for HLA-A (0.87) and DPB1 (0.81) loci. This paper presents also a global comparison of DPB1 allelic frequencies among 15 populations from four continents. As opposed to the DRB1 locus, overall DPB1 is shown to have a lower level of polymorphism and may be considered as neutral in all tested populations. DPB1 genetic diversity is correlated significantly with geography also, as found previously for DRB1. Two- and four-locus haplotype frequencies were determined and the significance of their linkage disequilibrium tested by an original non-parametric method. A significant positive linkage disequilibrium was found for 11 A-B, 16 B-DRB1, 7 DRB1-DPB1 and 3 A-B-DRB1-DPB1 haplotypes. The overall linkage disequilibrium between DRB1 and DPB1 was much lower than expected from the physical distance and lower than for A-B and B-DRB1 pairs. The implications of these results for bone marrow transplantation and for the evolution of HLA loci are discussed.

HLA-DPB1 polymorphism in the Thais of Southeast Asia

In this study we examined DPB1 allele frequencies in five ethnic Thai populations resident in different regions of Thailand and neighboring countries. In contrast to other Asian and Pacific populations such as the Japanese, Chinese, Korean, and Papua New Guineans, where DPB1*0501 has consistently been shown to be the most frequent allele, NE Thais and Thai-Khmers demonstrate a prevalence of DPB1*1301. Comparison of DPB1 allele frequencies in the Thais of SE Asia, with known frequencies in the Chinese and Japanese populations of E Asia, would appear to confirm previous calculations of genetic divergence between these Oriental populations.

A significant percentage of normal T lymphocytes express HLA-DP in the peripheral blood

HLA-DP expression has been widely investigated on T lymphocytes activated under different conditions. In the present study, a double staining procedure was used in flow cytometric experiments to define DP expression on normal peripheral blood T lymphocytes. In about two-thirds of the case analyzed, DP was expressed on a higher percentage of normal peripheral T lymphocytes than DR was. This was particularly true for 1 of the 16 cases investigated in which the percentage of T lymphocytes expressing DP was 46% and in which DP expression was mainly the prerogative of CD8+ and CD56+ lymphocytes.

Immunoelectron localization of HLA-DR, HLA-DP, and HLA-DQ antigens on the microvasculature in normal skin

BACKGROUND

Expression of HLA-DP and HLA-DQ antigens on the microvasculature in normal skin is uncertain.

OBJECTIVE AND METHODS

We investigated expression of HLA-DR, HLA-DP, and HLA-DQ antigens on the microvasculature in normal skin by light and electron microscopic immunohistochemistry.

RESULTS

HLA-DP and HLA-DQ antigens were expressed on the microvasculature, but the intensity of positiveness was variable. By immunoelectron microscopy, HLA-DR, HLA-DP, and HLA-DQ antigens were expressed on the endothelial cells of the microvasculature, but not on the pericytes and the smooth muscle cells. The luminal surface of endothelial cells had a stronger expression of these antigens than the abluminal surface.

CONCLUSION

HLA-DR, HLA-DP, and HLA-DQ antigens are expressed on endothelial cells of the microvasculature in normal skin.

Conservative evolution of the Mbc-DP region in anthropoid primates

To determine the organization of the DP region in the Mbc of anthropoid primates, we constructed contig maps from cosmid clones of the chimpanzee and orangutan, representatives of the infraorder Catarrhini, as well as of the cotton-top tamarin, a representative of the infraorder Platyrrhini. We found the maps to be remarkably similar to each other and to the previously published map of the human DP region. In each of the four species, the DP region consists of four loci arranged in the same order (DPB2 . . . DPA2 . . . DPB1 . . . DPA1) and in the same transcriptional orientation (tail-to-tail). The regions in the four species are of approximately the same length and many of the restriction sites are shared between species. The inserts of most Alu elements, of a ribosomal protein pseudogene, and of an IgC epsilon-like pseudogene are found in corresponding positions in all four species. The data indicate that the human-type organization of the DP region was established before the divergence of the Catarrhini and Platyrrhini lines more than 37 million years ago and that it has remained principally intact since that time. This conservation of the DP region is in striking contrast to the evolutionary instability of certain other Mbc regions, in particular those occupied by the DRB or C4 and CYP21 loci. We interpret the stability of the DP region as an indication that the region is being phased out functionally.

DP epitope mapping by using T-cell clones

To determine whether a correlation exists between the genomic HLA class II DP DNA polymorphism and cell surface expression and to detect the DP epitopes responsible for alloreactivity, anti-DP T-cell clones were generated against new PLT blank RFLP DPa and DPb-defined specificities. The clones were tested on the 10th IHWS B-LCLs and on local panel cells. Oligotyping of the tested cells made it possible to (a) correlate the DPa specificity with the DPB1*0402 specificity and (b) split DPb into DPB1*1001 and DPB1*1401. By comparing DNA sequences of the second exon to panel reactivity, the epitopes responsible for DPB1*1001 and 1401 were defined and attributed to beta-chain residues contributing to peptide selection inside the HLA groove. However, DNA sequences could not explain anti-DPa allospecificity, indicating that another structure not yet definable may be involved.

HLA-DP polymorphism in Sudanese controls and patients with insulin-dependent diabetes mellitus

Human leukocyte antigen (HLA) genes are candidates for susceptibility to insulin-dependent diabetes mellitus (IDDM). The association of IDDM with particular DR and DQ alleles has been reported in all populations studied, but its association with HLA-DP alleles has been controversial. To address this question we analyzed 19 DPB1 and 2 DPA1 alleles and their associations in well-characterized Sudanese (an admixture of Arab and Black) IDDM patients (n = 71) and ethnically matched controls (n = 86) using polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) typing. There were no significant differences between the patient and control groups in the DPB1 frequencies. DPB1*0201, *0401 and DPA1*01 were the most frequent alleles in both IDDM patients and control subjects. Significant positive and negative associations between DPB1 and DPA1 alleles were detected in both groups. A novel DPB1 allele included in DPB1*1701 was identified.

Analysis of HLA genotypes and susceptibility to insulin-dependent diabetes mellitus: association maps telomeric to HLA-DP

There is convincing evidence that certain combinations of alleles within the human leucocyte antigen (HLA) complex, particularly within HLA-DQ, are associated with either resistance or susceptibility to insulin-dependent diabetes mellitus (IDDM). A previous study conducted on a large, well-defined group of patients demonstrated that DQB1*0302 (DQw8) conferred 'dominant susceptibility' to IDDM while DQB1*0602 (DQw1.2) conferred 'dominant protection'. The availability of this population enabled us to further assess susceptibility associated with other class II alleles in an effort to map an outside HLA boundary of disease association. Using a group-specific polymerase chain reaction protocol and a series of oligonucleotide probes which define over twenty DP beta alleles, we studied 286 unrelated Caucasian patients with IDDM and 184 normal subjects. We found that while several alleles are increased (DPB1*0201, DPB1*0301, DPB1*0402) or decreased (DPB1*0101, DPB1*0202) in the diabetic population compared with the normal subjects, the HLA association with IDDM is considerably weaker at the DP locus. These data define the centromeric boundary for the HLA-associated susceptibility gene in IDDM, localizing susceptibility to the region telomeric to HLA-DP up to and including HLA-DQ.

HLA-DP distribution in Shanghai Chinese--a study by polymerase chain reaction--restriction fragment length polymorphism

One hundred and four normal unrelated Chinese were typed for HLA-DPA1 and DPB1 alleles by polymerase chain reaction-restriction fragment length polymorphism. Increased frequencies of HLA-DPA1*0201 and DPB1*0501 were found in this Chinese population as compared with those detected in Caucasoids and blacks.

Frequency of HLA-DPB1 alleles, including a novel DPB1 sequence, in the Northern Ireland population

HLA-DPB1 allele frequencies in 150 unrelated normal individuals from Northern Ireland were determined using oligonucleotide typing methods. HLA-DPB1*0401 was the most common allele in the population possessed by 75.3% of subjects, followed by DPB1*0201 (20.7%). In addition to these alleles, only HLA-DPB1*0402, -DPB1*0301, and -DPB1*0501 were present in subjects at frequencies greater than 10%. The results in this study are in broad agreement with other Caucasoid studies, but there is regional and ethnic variation in HLA-DP allele frequencies. Three DPB1 alleles were found to be in linkage disequilibrium with HLA-DR antigens determined by RFLP, namely, DPB1*0101 with DRw17 (Dw24 associated) RFLP, DPB1*0501 with DRw13-Dw19 RFLP, and DPB1*1901 with DRw13-Dw18 (Dw25 associated) RFLP. One individual revealed a novel DPB1 pattern of probe reactivity, which following DNA sequencing was found to be HLA-DPB1*2001. To assess the system used and to compare consistency of results between laboratories, 62 cell lines were oligotyped for HLA-DP. The results revealed the system described here to be extremely accurate and showed excellent agreement of HLA-DP typing results for cell lines between laboratories.

Crucial role of the third and fourth hypervariable regions of HLA-DPB1 allelic sequences in the mixed lymphocyte reaction

Since HLA-DP mismatches are known to induce proliferative response in MLR I, we investigated the real impact of the different DP alleles and the possible role of one or several hypervariable regions of the DPB allelic sequences. Accordingly, we performed MLR I between HLA-A, B, DR, DQ, and Dw identical individuals DP oligotyped after DNA amplification. A total of 23 one-DP-mismatched healthy stimulator and responder cells displaying nine different DP specificities were thus evaluated in 52 MLRs I. This allowed us to analyze the impact of amino acid composition of each of the six hypervariable regions independently of the amino acid matching or mismatching in the five others. We show here that DP combinations sharing the same amino acid sequence in the third (C) and fourth (D) hypervariable regions are associated with a low proliferative response in vitro (p less than 0.01). These data imply that a perfect HLA-DP matching may not be requisite in selecting bone marrow donors. Indeed, the choice of donors may rely on determination of these particular mismatched HVRs between the DP alleles involved especially in GvHD direction. This policy including prospective DP oligotyping should be of great interest, especially when MLRs I are false negative or nonevaluable. It will enable a better definition of which DP mismatches are acceptable in BMT.

Expression of MHC class II antigens (HLA-DR, -DP, and -DQ) on human gastric epithelium

Class II antigen expression on gastric epithelium was investigated using an immunoperoxidase method in relation to the degree of inflammatory cell infiltration in the lamina propria. Sixty-six biopsy specimens from 43 patients with chronic gastritis were examined. The frequency of HLA-DR expression in specimens with cell infiltration was 94%, while that in specimens without cell infiltration was 24%. There was significant difference in the frequency of HLA-DR expression between the two groups (P less than 0.01). HLA-DR was most intensely expressed in the glandular neck portion. The frequency and extent of class II antigen expression on gastric epithelium with cell infiltration were in the following order: DR greater than DP greater than DQ. The extent of DR and DP, but not DQ expression generally paralleled the degree of cell infiltration. Intestinal metaplasia was found in 13 specimens. In the area of intestinal metaplasia, epithelial class II staining was absent except for one specimen. These results suggest that the respective genes of three class II antigens are regulated by different mechanisms and that an immunological mechanism plays a role in the pathogenesis of gastritis.

DPB1 polymorphism in rheumatoid arthritis: evidence of an association with allele DPB1 0401

HLA-DP polymorphism was examined in 71 rheumatoid arthritis patients and 148 controls, using dot-blot analysis with 14 synthetic oligonucleotide probes specific for the variable region of the DPB1 second exon. The DPB1 0401 allele was found to be significantly more frequent in RA patients than in controls (77.46% vs 55.40%, p less than 0.002, pc less than 0.03, relative risk value: 2.74). An association between DPB1 0401 and seropositivity for rhumatoid factors was also observed: 44 of the 55 seropositive RA patients were DPB1 0401 (p less than 0.001). Analyzing the HLA DPB1 alleles frequencies in 57 HLA-DR-typed RA patients did not show any linkage between the DPB1 0401 and the DR4 specificities. Furthermore, the DPB1 0401 homozygous frequency was increased in DR4-negative RA patients. Our findings suggest an independent role of the DPB1 0401 allele in the genetic susceptibility to RA.

Isolated HLA-DP mismatches between donors and recipients do not influence the function or outcome of renal transplants

The matching of donors and renal graft recipients for human leukocyte antigens A, B, and DR has been shown to exert beneficial effects on the outcome of transplantation. Until the advent of polymerase chain reaction amplification-based genotyping, the effect of HLA-DP compatibility on graft survival could not be thoroughly investigated. HLA-DP compatibility has been determined in three living-related transplants and 34 cadaveric transplants for donor-recipient pairs matched for HLA-DR and -DQ. The effect of DP mismatching on graft survival and function was assessed. No clear benefit from matching donor and recipient for HLA-DP could be discerned.

Frequency of DPB1*0401 is significantly decreased in patients with allergic asthma in a mulatto population

Allergic asthma (AA) is a multifactorial disease in which the IgE hyperresponsiveness to mite allergens is determinant for its pathogenesis and clinical picture. We have reported previously that IgE responsiveness to mite allergens in AA patients is linked to HLA and possibly controlled by a dominant suppression (Is) gene of that region. The present population study was done to detect alleles involved in the genetic control of mite IgE response that accompanies AA, using polymerase chain reaction and oligonucleotide DNA typing of DP locus. Instead of finding any significant positive association with AA, in this study we found that the allele DPB1*0401 is present mainly in the nonallergic control population and strikingly absent in patients (p less than 0.008), suggesting that this gene could confer resistance to AA and other atopic diseases. Our results add more evidence regarding the existence of Is genes in the HLA region involved in the control of IgE immune response to environmental allergens. Furthermore, they suggest that genes of HLA are important genetic components involved in the etiology of AA.

[HLA class II DP antigens and bone marrow transplantation]

The biochemical structure of the HLA class II DP antigens is close to that of the remainder DR and DQ isotypes. Nevertheless, they may play a peculiar functional role. Their importance in bone marrow transplantation, where a complete HLA class II identity between graft donor and recipient is requested, is not yet known. The detection of a DP mismatch by using the mixed lymphocyte reaction is quite difficult. The role of such a mismatch in the incidence of graft versus host disease (GVHD) or graft rejection has to be defined. Studies on large series of recombinant families, using oligotyping, are necessary.

Gene polymorphism of HLA-DPB1 and DPA1 loci in caucasoid population: frequencies and DPB1-DPA1 associations

The genetic polymorphism of the HLA-DPB1 and DPA1 loci was studied in 60 unrelated caucasoid individuals by PCR-RFLP. The polymorphic second exon of DPB1, the third exon of DPA1, and the transmembrane DPA1 exon were specifically amplified in vitro by polymerase chain reaction (PCR). Amplified DNAs were digested with selected enzymes. Twenty patterns were obtained with DPB1 defining 20 DPB1 alleles. Thirty-nine homozygous cell lines were used as HLA-DP reference cells. The results obtained with these cell lines were compared to those obtained by PLT, RFLP, and SSO. Although three subdivisions of the allele DPA1*01 were reported, DPA1*0103 was the only represented one in the caucasoid population. In the studied population, it was the most frequent DPA1 allele (76.6%), whereas DPA1*0201 frequency is 23.3%. DPB1*0401 and DPB1*0402 are the most frequent among the DPB1 alleles (40.0% and 13.3%, respectively). This may lead to a lower HLA-DPB1 diversity among caucasoids. Certain HLA-DPB1 alleles associate exclusively with one DPA1 allele (DPB1*0401, 0402, and 0301 with DPA1*01 and DPB1*0101, 0501, and 1701 with DPA1*0201) whereas the others can associate with both DPA1 alleles. This by itself can create another kind of polymorphism, indicating the importance of HLA-DPA1 typing. Thus, PCR-RFLP seems to be one of the best DNA typing methods: it represents direct, accurate, fast, and nonradioactive typing for both HLA-DPA1 and HLA-DPB1 alleles.

HLA-DR expression in macaque neuroendothelial cells in vitro and during SIV encephalitis

HLA-DR expression in neuroendothelial cells (NEC) was studied during the course of SIV encephalitis in rhesus monkeys. HLA-DR determinants were detected on NEC in monkeys with SIV encephalitis, but not in control animals. In situ hybridization with an SIV probe indicated that HLA-DR expression was not a consequence of SIV replication within NEC. Cultured rhesus NEC stimulated with gamma interferon expressed HLA-DR to a higher degree than cultured brain fibroblasts or astrocytes. These data support the contention that NEC participate in retrovirus-induced inflammation and autoimmunity within the central nervous system.

Positive correlation between oligonucleotide typing and T-cell recognition of HLA-DP molecules

The identification of 19 different HLA-DPB1 sequences implicates the existence of more DP specificities than can be typed for with cellular methods. How many of the DP beta sequences can be specifically recognized by T cells, and which of the polymorphic regions can contribute to the specificity of allorecognition, is not known. In order to investigate the distribution and the immunological relevance of recently described DPB1 alleles, we have typed a panel of 98 randomly selected Dutch Caucasoid donors for the HLA-DPB1 locus by oligonucleotide typing. Comparison of the typing results with primed lymphocyte typing (PLT) defined DP specificities shows an extremely good correlation. Moreover, additional alleles could be defined by oligonucleotide typing reducing the number of DP blanks in the panel. By selecting the appropriate responder stimulator combinations we were able to show that distinctive PLT reagents against oligonucleotide defined specificities DPB1*0401, DPB1*0402, DPB1*0901, and DPB1*1301 can be generated. To investigate in more detail which part of the DP molecule is responsible for the specificity of T-cell recognition, T-cell clones were generated against HLA-DPw3. The clones were tested for the recognition of stimulators carrying DPB1 alleles which had been defined by oligonucleotide typing and sequence analyses and which differed in a variable degree from DPB1*0301. The recognition patterns demonstrated that differences of one amino acid in polymorphic regions situated either in the beta sheets or alpha helix of the hypothetical model of the HLA class II molecule can eliminate T-cell recognition. Furthermore, sequence analyses revealed a new DPB1 allele designated DPB1*Oos.

Characterization of skin-infiltrating lymphocytes in patients with psoriasis

In this study, skin-infiltrating cells in psoriasis patients were characterized in biopsies from both involved and uninvolved skin. Histologic examination of biopsies showed the presence of both CD4+ and CD8+ T cells and the lack of B lymphocytes. Skin biopsies were also placed in tissue culture medium supplemented with human serum, interleukin-2 (IL-2), and irradiated autologous blood lymphocytes. T lymphocytes grew from both plaques and univolved skin biopsies and consisted of a heterogeneous population of T-cell subsets. The immunophenotypic analysis of cultured cells was comparable to the histologic examination on frozen section, i.e., there was a greater number of CD4/CDw29+ cells than CD8+/CD45+ cells. Cultures were tested in the primed lymphocyte test (PLT) and cell-mediated lympholysis (CML) assays. All cultures tested demonstrated secondary proliferative but not cytolytic reactivity. The PLT results indicate that the cell cultures generated are autoreactive. This autoreactivity was found to be directed against non-human leukocyte antigens (HLA), i.e., minor HLA with some restriction to major HLA antigens.

Incidence and specificity of HLA-DP antibodies in pregnancy sera

A total of 630 human pregnancy sera were investigated for HLA-DP antibodies (ab) by monoclonal antibody-specific immobilization of leukocyte antigens (MAILA) using monoclonal antibody (mAB) B7/21.2 and selected B-lymphoblastoid cell lines from the Tenth International Histocompatibility Workshop reference panel. DP-specific abs were detected in 86 of 330 sera (26.1%) of a retrospective series selected for positive reactions in lymphocytotoxicity screening, and in 29 of 300 unselected sera (9.7%) of a prospective series. Approximately 80% of DP-reactive sera were also positive in lymphocytotoxicity test for class I and/or class II ab. On the other hand, sera containing lymphocytotoxic ab for both class I and class II ab revealed the highest incidence of DP ab (35%). Out of 115 DP-reactive sera, 28 clearly presented one or more DP specificities. Absorption/elution studies revealed complex patterns of reactivity in some sera which were similar to those of known mABs and possibly reflect supertypic DP specificities and/or serological cross-reactions. Serological DP typing of individuals by the MAILA technique appears promising.

HLA-DP incompatibilities induce significant proliferation in primary mixed lymphocyte cultures in HLA-A, -B, -DR and -DQ compatible individuals: implications for allogeneic bone marrow transplantation

The major part of the proliferative response in primary mixed lymphocyte cultures (MLC) is caused by HLA-DRB1 incompatibilities. In DRB1-matched pairs the proliferation induced by HLA-DRB3, -DQ and -DP mismatches may be unmasked. In most previous studies the influence of HLA-DP incompatibilities in primary MLC has been investigated in homozygous typing cells representing only a few Dw specificities. We were interested in determining the stimulatory capacity of isolated HLA-DP mismatches, ascertained by RFLP analysis, in primary MLC in HLA-A, -B, -DR and -DQ compatible, unrelated heterozygous individuals of many different Dw specificities. Thirty-eight MLCs performed with cells from related pairs and 67 with cells from unrelated pairs were evaluated. All but nine of the MLCs were analyzed in both directions, giving a total of 201 investigated reactions. The relative responses (RR) in the three MLCs performed between DP incompatible, related pairs were all positive (RR greater than or equal to 8%). Eighty of 82 MLCs performed with cells from DP incompatible, unrelated individuals were positive, whereas 37 of 46 MLCs between DP compatible, unrelated pairs were negative (RR less than 8%) (p less than 10(-10)). The magnitude of the RR was influenced by the number of DP mismatches. Thus, the mean RR was approximately twice as high in MLCs in which responder and stimulator cells differed by two DP antigens (mean RR 60.5%) compared with reactions with only one DP mismatch (mean RR 35.4%) (p less than 10(-3)). RFLP-defined HLA-DP incompatibilities predict a positive primary MLC in HLA-A, -B, -DR and -DQ matched individuals with a high degree of accuracy (98%).(ABSTRACT TRUNCATED AT 250 WORDS)

Antigen-presenting capacity in patients with sarcoidosis

Antigen-presenting capacity by monocytes and AMs was determined in 13 patients with sarcoidosis and nine healthy control subjects, using PPD as the antigen. The patients and healthy control subjects all had positive PPD skin tests. Monocytes from both the control subjects and the patients with sarcoidosis exhibited antigen-presenting capacity to autologous peripheral T-lymphocytes, without any significant difference between the two groups. The AMs from patients, but not control subjects, demonstrated antigen-presenting capacity to autologous peripheral T-lymphocytes. Antigen-presenting capacity by monocytes and AMs to lung T-lymphocytes was lower than to peripheral T-lymphocytes, but not significantly. Antigen-presenting capacity was not significantly different between patients with sarcoidosis who had positive and negative PPD skin tests. The mechanism of enhanced antigen-presenting capacity by AMs in sarcoidosis is uncertain at present, but no significant difference was observed in DR antigen expression on AMs between controls and patients with sarcoidosis, and the addition of exogenous IL-1 or IFN-gamma did not induce antigen-presenting capacity by AMs in controls, suggesting that neither increased DR antigen expression on AMs nor increased release of IL-1 or IFN-gamma from AMs is responsible. Thus, these results suggest that T-lymphocyte activation in sarcoidosis may in part be attributable to an enhanced antigen-presenting capacity by AMs.

Class II (HLA-DR, -DP, and -DO) antigens on intestinal epithelia in ulcerative colitis, Crohn's disease, colorectal cancer and normal small intestine

Class II antigens in involved colonic epithelia of ulcerative colitis (UC), Crohn's disease (CD), colorectal cancer, and epithelia of normal small intestine were investigated using an immunoperoxidase method. Ten normal colonic mucosa served as normal controls. Ten specimens were studied for each group. Normal colonic epithelia did not express class II antigens. In colonic diseases; (1) with regard to the frequency and extent of class II antigens on epithelia. HLA-DR antigens were the most highly and greatly expressed, followed by HLA-DP and then HLA-DQ antigens. (2) The extent of HLA-DR and -DP, but not HLA-DQ, expression on epithelia of UC and colorectal cancer seemed to be positively correlated with the degree of mononuclear cell infiltration in the lesion. (3) The extent of class II antigen expression on colonic epithelia in CD was not related to the degree of mononuclear cell infiltration in the lesion. (4) The extent of HLA-DR and -DP expression on epithelia of colorectal cancer seemed to be positively correlated with increasing undifferentiation. In the normal small intestine, where HLA-DR antigens were physiologically expressed on epithelia. HLA-DQ antigens were not expressed. The heterogeneity among colonic diseases, and between the physiological and pathological status, may reflect differences in immunoregulation.

Rapid HLA-DPB typing using enzymatically amplified DNA and nonradioactive sequence-specific oligonucleotide probes

A simple and rapid method for characterizing the polymorphism at the HLA-DPB1 locus has been developed. The procedure involves the selective amplification of the polymorphic second exon of the DPB1 locus by the polymerase chain reaction (PCR), followed by hybridization of the amplified DNA with 15 nonisotopic sequence-specific oligonucleotide probes. There are no sequences within the second exon of the DPB1 locus that uniquely define an allele; rather, each allele appears to arise from the shuffling of a limited number of polymorphic nucleotide sequences in six regions of variability. Consequently, individual alleles are identified by the pattern of hybridization of the 15 probes. Two formats for typing are described. In Format I (the dot-blot), the amplified DNA is ultraviolet (UV) cross-linked to a nylon membrane and hybridized with the oligonucleotide probes which are covalently labeled with horseradish peroxidase (HRP). In Format II (the reverse dot-blot), the oligonucleotides, which have poly-T tails, are bound to the membrane and the immobilized array of probes is hybridized to the PCR product which has incorporated biotinylated primers during the amplification process. In both formats, hybridization is detected by a simple colorimetric reaction. The application of this technology to the fields of tissue typing and individual identity is discussed.

Analysis of HLA-DP in HLA-DR/GLO recombinant families and in the population of south-western France

The existing estimates of the recombination fraction between DR and DP are quite variable and often based on anecdotal observations. We have estimated the DR/DP crossover frequency on the basis of families typed for HLA markers and GLO. The frequency of DR/GLO crossing over was 8.7% (23/264 informative meioses), maternal recombinations being about twice as frequent as paternal ones. Of 17 DR/GLO recombinant families typed for DPw1-6, DP was informative in 11 (13 recombinations) but only one of these gave rise to a DR/DP crossover. According to these data the DR/DP recombination fraction is below 1%, in contrast to some earlier published materials. HLA-DR/DP haplotypic associations on 127 informative Caucasoid haplotypes have been evaluated. In agreement with previous studies, DR3 was positively associated with DPw1 and, in addition, DR7 was found to be positively associated with DP-blank (not DPw1-6). The rare DPw6 allele is possibly associated with the DR4, Dw14 allele. The DR-DP haplotype profiles suggest other associations which might become significant if larger materials are tested. The frequency of DP alleles in a random material (N = 201) was found to be in accordance with most of the previously published frequences on European Caucasoids with DPw4 as the predominating frequency (gene frequency 40%) and a blank frequency of 27%.