HLA-DRB1* and allergy to Parietaria: linkage and association analyses

In this study, we used the affected sibling-pairs approach to investigate the linkage of HLA (human leukocyte antigen)-DRB1* with phenotypes related to allergy to Parietaria, the most common pollinosis in Mediterranean countries. The study population consisted of 51 nuclear families (235 subjects). Linkage was detected with Parietaria skin test positivity (p < 0.01), presence of IgG and IgE antibodies specific for the major allergen Par o 1 (p < 0.020 and p < 0.025, respectively), and absence of Par o 1-specific IgE (p < 0.020).High levels of Par o 1-specific IgG were associated with DRB1*1101 and/or DRB1*1104 (p < 0.0001 and p < 0.0119, respectively) in parents and probands. High levels of Par o 1-specific IgE were associated with DRB1*1104 in parents (p < 0.017) and with DRB1*1101 in probands (p < 0.0146). When siblings were categorized according to high/low total IgE levels (125 IU/ml and <125 IU/ml, respectively), high IgE antibody response was associated with DRB1*1104 in siblings with low total IgE (p < 0.034) and with DRB1*1101 in siblings with high total IgE (p < 0.05).These results demonstrate that HLA-DRB1*, or genes in linkage disequilibrium, contributes to susceptibility to Parietaria allergy and that total IgE levels can discriminate population subsets where different alleles (at the HLA region or at loci in linkage disequilibrium) contribute to control allergen-specific IgE synthesis.     

Association of responsiveness to the major pollen allergen of Parietaria officinalis with HLA-DRB1 alleles a multicenter study

Parietaria, a plant belonging to the family of Urticaceae, is a major source of allergenic pollen in Europe. In the context of a multinational study, we investigated whether in allergic subjects antibody response towards Par o l, the major allergen from P. officinalis, was associated with defined HLA-DRB1^* alleles.

The study population consisted of 234 allergic patients: 65 from Bulgaria, 30 from Israel, 99 from Italy, and 40 from Spain.

In the Italian study group, the prevalence of ST positivity to Parietaria was 77%. In Parietaria ST-positive subjects, the prevalences of IgG and IgE serum Ab towards Par o 1 were 91% and 75%, respectively. HLADRB1*1101 and/or 1104 were significantly positively associated with the presence of IgG Ab and with high levels of IgE Ab towards this allergen (p = 0.0007) and p = 0.012, respectively).

In the Spanish study group, the positive association of DR 1100 with responsiveness to Par o 1 was confirmed (p = 0.02, RR = 4, and p = 0.002, RR = 7, for IgG and IgE Ab, respectively). None of the Bulgarian patients had IgE Ab to Par o 1, whereas IgG Ab response was observed in 7 out of 65 subjects and was positively associated with DRB 1^*1101 and/or 1104 (p = 0.025). In the Israeli study group, responsiveness to Par o 1 was not associated with specific HLA-DRB1^* alleles.

In conclusion, this study shows that in allergic patients from three European populations antibody response to the major allergen from the pollen of Parietaria is associated with HLA-DRB1^* 1101 and/or 1104. Our data suggest that this association is stronger in subjects monosensitized to Parietaria.     

Paroxysmal nocturnal hemoglobinuria: significant association with specific HLA-A, -B, -C, and -DR alleles in an Italian population

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by the expansion of a PIG-A mutated hematopoietic stem cell. An immune-mediated origin has been suggested for this disease. Because HLA genes represent a susceptibility factor for autoimmunity, we investigated HLA genotype in 42 Italian PNH patients compared with 301 control subjects of the same ethnic origin. A significantly increased frequency of the HLA class I alleles A*0201 (p < 0.05), B*1402 (p < 0.001), and Cw*0802 (p < 0.005), and of the HLA class II DRB1*1501 (p < 0.01) with the linked DQB1*0602 (p ≤ 0.05) and DRB1*01 (p ≤ 0.05) with the linked DQB1*0501 (p ≤ 0.01) alleles, has been observed. Notably, a fourfold increase of the haplotype B*1402, Cw*0802 (p < 0.0005) and a 15-fold increase of the Mediterranean haplotype A*33, B*1402, Cw*0802, DRB1*0102, DQB1*0501 (p < 0.005) was also revealed. This association may provide new insights into the autoimmune pathogenesis of PNH.     

HLA-encoded susceptibility to insulin-dependent diabetes mellitus is determined by DR and DQ genes as well as their linkage disequilibria in a Chinese population

HLA-DRB1 and -DQB1 genes were analyzed in 98 Chinese IDDM patients and 205 control subjects from Taiwan. The DRB1^*0301-DQB1^*0201 haplotype conferred strong susceptibility (RR = 7.7, p_c < 10−5). DRB1^*0405 also conferred susceptibility (RR = 3.1, p_c < 0.0005) whereas DRB1^*0403 (RR = 0.7) and DRB1^*0406 (RR = 0.2) conferred protection. Indeed, the relative risk for the DRB1^*0405-DQB1^*0302 haplotype (RR = 33.7, p_c < 0.002) was 48 and 168 times higher than those conferred by the DRB1^*0403-DQB1^*0302 and DRB1^*0406-DQB1^*0302 haplotypes, respectively, suggesting that the protection conferred by DRB1^*0403 and 0406 is dominant over DQB1^*0302. The strong linkage disequilibrium observed between DQB1^*0302 and DRB1^*0403(0406) can thus explain the surprising finding that the frequency of DQB1^*0302 was not significantly increased in the Chinese IDDM patients (RR = 0.9). Because the DRB1^*0405-DQB1^*0302 haplotype (RR = 33.7) conferred higher susceptibility than the DRB1^*0405-DQB1^*0401 (RR = 2.5) or DRB1^*0405-DQB1^*0301 (RR = 2.1) haplotypes, DQB 1^*0302 is indeed a susceptibility factor, while both DQB1^*0301 and DQB1^*0401 may confer protection against IDDM. The increased frequency of the protective DQB1^*0401 allele in patients compared to controls is due to linkage disequilibrium between DRB1^*0405 and DQB1^*0401. Interestingly, the previously demonstrated protective effect of DQB1^*0602 was not very strong in the Chinese (RR = 0.4). Our results suggested that HLA-encoded susceptibility to IDDM is determined by the combined effects of all DR and DQ molecules present in an individual. Therefore, the genotypic combinations of DR and DQ genes as well as their linkage disequilibria can influence IDDM susceptibility. At least four DR and DQ molecules conferring high susceptibility (DRB1^*0301, DRB1^*0405, and DQ/β0301/0201 and 0301/0302) occur at high frequency in the Chinese population. However, linkage disequilibria between highly susceptible DR and protective DQ or vice versa (e.g., DRB1^*0405-DQB1^*0301(0401] and DRB1^*0403[0406]-DQB1^*0302) are probably responsible for the lower incidence of IDDM in the Chinese.     

Type 1 diabetes in Jewish Ethiopian immigrants in Israel: HLA class II immunogenetics and contribution of new environment

The interrelationship between human leukocyte antigen immunogenetics and environmental factors and their contribution to the emergence of type 1 diabetes (T1D) were studied in Jewish immigrants from Ethiopia in Israel. This community displays high incidence of T1D, and is unique both by its ethnic segregation and its rapid exposure to a new environment after the immigration. The study population consisted of 152 Ethiopian Jews living in Israel, 33 with T1D and 119 unrelated controls. Human leukocyte antigen class II susceptible and protective alleles in the Jewish Ethiopian patients were similar to those in patients of other ethnic groups in Israel and in non-Jewish Ethiopian patients, with a few exceptions. Three haplotypes were markedly associated with diabetes in Jewish Ethiopian patients: DRB1*0301 DQA1*05 DQB1*02 (OR 4.4, p < 0.001); DRB1*0404 DQA1 03 DQB1*0302 (OR 19.2, p = 0.006), and DRB1*0405 DQA1*03 DQB1*0302 (OR 87.8, p < 0.001). The highly susceptible allele DRB1*0301 was more common in the general Ethiopian population (25.2%) than in all other ethnic groups in Israel, which may render this community prone to the disease. The age at onset of disease in patients with two susceptible haplotypes was negatively correlated with the duration of living in Israel (r = −0.621, p = 0.04). We concluded that ongoing exposure of genetically predisposed immigrants from Ethiopia to diabetogenic environmental factors eventually leads to a high incidence of overt diabetes in this ethnic group.     

Analysis of HLA-DM polymorphisms in sarcoidosis

Sarcoidosis is a multisystemic granulomatous disorder showing significant increases in the HLADRB1 ^*11, ^*12, ^*14 and ^*08 alleles in the Japanese population. To evaluate the role of polymorphism in the DMA and DMB genes in predisposition to sarcoidosis, seventy Japanese patients with sarcoidosis and 95 unrelated healthy controls were analyzed in the third exon polymorphisms within the DMA and DMB genes by the PCR-RFLP method. There were no differences in the distribution of DMA alleles between the patient and control groups. The frequency of DMB^*0102 was higher (p < 0.05) and that of DMB^*0101 was lower (p < 0.05) in the patients than in the healthy controls. However, this association and negative association could be explained by linkage disequilibrium with the disease-associated DRB1 alleles. The DMA and DMB genes do not primarily confer the susceptibility to sarcoidosis.     

Pemphigus Vulgaris Autoantibody Response is Linked to HLA-DQB10503 in Pakistani Patients

ABSTRACT: Pemphigus vulgaris (PV) is an autoimmune disease of the skin and mucous membranes characterized by an autoantibody response against an epidermal cadherin. We performed high resolution HLA class II typing in 19 patients with PV from Rawalpindi, Pakistan and 19 non-Jewish European PV patients from Boston by sequence-specific oligonucleotide probe hybridization. The results were compared with two separate ethnically matched control populations. We found that PV patients from Pakistan had significantly increased frequencies of DRB1*1404 ( p = 0.01), DQA1*0101 ( p = 0.02), and DQB1*0503 ( p = 0.01). Among the patients of non-Jewish European ancestry, DRB1*1401 ( p < 10⁻⁶), DQA1*0101 ( p < 10⁻⁵) and DQB1*0503 ( p < 10⁻⁶), were increased in PV patients. Formal linkage analysis between the major histocompatibility complex and the PV antibody was performed in 67 relatives of the 19 Pakistani patients. The results showed strong evidence for linkage of HLA-DRB1*1404, DQA1*0101, DQB1*0503, with the presence of PV antibody in relatives’ families with a significant logarithm of the odds score of 6.06. Based on the three dimensional structure of class II molecules, we propose that HLA-DQA1*0101 and DQB1*0503, encode a negatively charged P9 peptide binding pocket of the DQ molecule and are significantly associated with susceptibility to PV in non-Jewish populations.     

Antigen-processing organelles from DRB1*1101 and DRB1*1104 B cell lines display a differential degradation activity

We have developed an in vitro assay for tetanus toxin (tt) C fragment (C-fr) degradation. Purified endosomes (abbreviated endosomes 1101 or 1104) and lysosomes (abbreviated lysosomes 1101 or 1104) from the DRB1*1101 (Gly 86) and DRB1*1104 (Val 86) B cell lines were used to degrade ¹²⁵I-labeled C-fr in vitro. Using three distinct methods of analysis, we show that the capacity of endosomes and lysosomes to degrade the tt C-fr or tt synthetic Y-P30 peptide differed. Using sodium dodecylsulfate-polyacrylamide gel electrophoresis, ¹²⁵I-labeled C-fr degradation patterns observed either with endosomes 1101/1104 or lysosomes 1101/1104 are distinct both in terms of the number of fragments and the kinetics of generation of the fragments. These results were confirmed by high-performance liquid chromatography analysis, where we observed that the elution profiles of the ¹²⁵I-labeled Y-P30 peptide digested by endosomes 1101/1104 were different compared to those obtained with lysosomes 1101/1104. Furthermore, the kinetics of degradation of ¹²⁵I-labeled Y-P30 were faster with lysosomes 1104 than with lysosomes 1101. This difference in activity of the 1101 and 1104 organelles was also found in a functional assay where we showed that the activation capacity of the P30 peptide was diminished when digested by lysosome 1104, regardless of the antigen-presenting cell (APC) used, whereas endosomes 1101 or lysosomes 1101 modified P30 peptide in a form that discriminated between presentation by 1101 or 1104 APC. Taken together, these results suggest that the differential processing and presentation displayed by the DRB1*1101 and DRB1*1104 APC is due partly to a different enzymatic content and partly to the dimorphism at position DRβ86.     

Linkage between HLA-DRB1 and -DRB3 types in the Japanese population analyzed by oligonucleotide genotyping.

We analyzed linkage between HLA-DRB1 and -DRB3 types in 219 Japanese donors by oligonucleotide genotyping. In the Japanese population, DRB1*1201 was linked with DRB3*0101 in all donors analyzed; in contrast, most Caucasian DRB1*1201 is known to be linked with DRB3*02(01/02) (*0201 or *0202). However, most DRB1*1202 was linked with DRB3*0301. Thus, the two DRw12-related DRB1 types are linked with DRB3 types distinct from each other. All the three DRw14-related DRB1 types, DRB1*1401, DRB1*1402, and DRB1*1405, were linked with DRB3*02(01/02) in the Japanese population, contrasting with the known linkage between DRB1*1402 and DRB3*0101 in other ethnic populations. The serologically "blank" DR type, DRB1*1403, was linked with DRB3*0101. Other DRB1 types, DRB1*0301, DRB1*11(01/04) (*1101 or *1104), and DRB1*13(01/02) (*1301 or *1302) in the Japanese population were linked mostly with the same DRB3 types, like those known in other ethnic populations.     

Endogenous retroviral long terminal repeats of the HLA-DQ region are associated with susceptibility to insulin-dependent diabetes mellitus

HLA-DQ genes are the main inherited factors predisposing to IDDM. This gene region harbors long terminal repeat (DQ LTR) elements of the human endogenous retrovirus HERV-K, which we analyzed for a possible association with disease. We first investigated whether LTR segregate with DQ alleles in families. Members (n = 110) of 29 families with at least one diabetic child, unrelated patients with IDDM (n = 159), and healthy controls (n = 173) were analyzed. Genomic DNA was amplified for DQ LTR3 by a nested primer approach as well as for DQA1 and DQB1 second exons, to assign DQA1 and DQB1 alleles. DQ LTR segregated in 24 families along with DQ alleles. Of the 29 families, 20 index patients were positive for DQ LTR. The DQ LTR was in all patients on the haplotype carrying the DQA1 ^*0301 and DQB1 ^*0302 alleles. A majority of patients had DQ LTR (62%) compared with controls (38%) (p < 1.3 × 10^{− 5}), even after matching for the high-risk alleles DQA1 ^*0501, DQB1 ^*0201-DQA1 ^*0301, and DQB1 ^*0302 (79% of patients and 48% of controls; p < 0.02). Subtyping for DRB1 ^*04 alleles in all DQB1 ^*0302 ⁺ individuals showed 56% DRB1 ^*0401, DQB1 ^*0302 [LTR⁺ patients vs. 29% controls with the same haplotype (p < 0.002). In conclusion, these data demonstrate the segregation of DQ LTR with DQA1, DQB1 alleles on HLA haplotypes. Furthermore their presence on DRB1 ^*0401-, DQA1 ^*0301-, and DQB1 ^*0302-positive haplotypes suggest that they contribute to DQ-related susceptibility for IDDM. Human Immunology 50, 103–110 (1996)     

HLA-DRB and -DQB1 polymorphism in the Macedonian population

HLA-DRB1, DRB3/4/5 and DQB1 polymorphism has been studied in a population of 80 unrelated healthy Macedonians using molecular methods. Twenty-five different DRB1 alleles were identified of which DRB1*1104, *1501, *1601, and *1101 were found most frequently. Among the 15 identified DQB1 alleles, two were predominant: DQB1*0301 and *0502. The most frequent three-locus haplotypes were DRB1*1104-DRB3*02-DQB1*0301 (18%/), DRB1*1101-DRB3*02-DQB1*0301 (9%) and DRB1*1601-DRB5*02-DQB1*0502 (10%). Polymorphism for DRB1*04, *13 and *15 haplotypes was extensive. Eleven different DR2-related haplotypes were found, some of which were unusual for European populations: DRB1*1501-DRB5*0102-DQB1*0502, DRB1*1501-DRB5*02-DQB1*0502, DRB1*1501-DRB5*0102-DQB1*0601.     

Atopic asthma and TNF-308 alleles: linkage disequilibrium and association analyses

The association of a tumor necrosis factor -308 allele (TNF2) to asthma has been reported in some studies but not in others. The aim of this study was to test this association in a population recruited on the basis of allergy to Parietaria. In the study population, asthma was positively associated to HLA-DRB1*03 (p = 0.01) and to the haplotype TNF2/DRB1*03 (p = 0.02). In the parent subgroup, the proportion of asthmatics was increased in patients with TNF2 (p = 0.01), but the primary association of asthma was to the haplotype TNF2/DRB1*1104 (p = 0.005). The study population was subdivided according to prick skin test (ST) positivity to Lolium, Parietaria, and D. pteronyssinus. Asthma was associated to HLA-DRB1*03 and to the haplotype TNF2/DRB1*03 (p = 0.0015 and 0.0001, respectively) in patients ST positive to Lolium, and to the haplotype TNF2/DRB1*1104 (p = 0.025) in patients ST positive to Parietaria. The transmission disequilibrium test detected excess transmission of HLA-DRB1*03 and of the haplotype TNF2/DRB1*03 (p = 0.03 and 0.04, respectively) to siblings with asthma and ST positivity to Lolium and of HLA-DRB1*1104 and of the haplotype TNF2/DRB1*1104 (p = 0.04 and 0.015, respectively) to siblings with asthma and ST positivity to Parietaria. Taken together, these observations indicate that the haplotypes TNF2/DRB1*03 and TNF2/*B1*1104 contain alleles controlling atopic asthma in patients with sensitization to Lolium and Parietaria, respectively. This suggests that the association of asthma to TNF2 reflects linkage disequilibrium with genes influencing specific immune response.     

Soluble HLA Class I Antigens in Patients with Type I Diabetes and Their Family Members

Our objective was to study a possible contribution of MHC genes to S-HLA-I secretion in patients with Type I diabetes. Quantitatively, we used a highly sensitive enzyme-linked immunoassay to measure S-HLA-I in the serum of a total of 39 patients with Type I diabetes, as well as 36 kinships of 12 diabetic patients and 82 normal individuals with known HLA-phenotypes.

S-HLA-I levels were abnormally elevated in patients or their non-diabetic relatives compared to normal controls (p < 0.0009). No complete HLA-haplotype had been identified to be correlated with high or low S-HLA-I secretion. Only the HLA-A23 or A24 (splits of HLA-A9) positive individuals sera were found to contain high S-HLA-I concentrations in all populations studied. The difference in S-HLA-I levels of HLA-A24 patients (n = 4) or their HLA-A24 positive non-diabetic relatives (n = 10) to the group of HLA-A24 normal controls (n = 15) was statistically highly significant (p < 0.0005 and p < 0.0009, respectively). The results suggests that HLA-A24 may confer additional independent risk for the disease expression in male children but not in female siblings. Nevertheless, the data implies that the patients or their non-diabetic relatives carrying the HLA-A24 have increased risk of developing ICA associated with high S-HLA-I levels compared to HLA-A24 negative probands or their kinships with low levels of S-HLA-I. This effect occurred irrespective to other diabetes related HLA-DR alleles.

In summary, the results show a pronounced genetic heterogeneity of Type I diabetes with MHC control of the expression of S-HLA-I and possible involvement of hormonal factors that might potentiate a specific synthesis of S-HLA-I. The findings have implications for identifying individuals with a possible risk for developing the disease.     

Insulin-Dependent Diabetes Mellitus in Non-DR3/Non-DR4 Subjects

ABSTRACT: Five to 20% insulin-dependent diabetes mellitus (IDDM) patients do not bear the classical HLA class II DR3 or DR4 susceptibility haplotypes. We have studied the clinical characteristics, anti-islet cell antibodies (Ab) and HLA class II genotypes in 72 non-DR3/non-DR4 Caucasian patients, mainly adults, presenting with clinically typical IDDM. The DRB1*08-DQB1*0402-DQA1*0401 haplotype frequency was increased in the patients compared to 272 non-DR3/non-DR4 controls (OR = 5.9, Pc < 0.005). This association was even stronger in the Ab-positive patients (DRB1*08: OR = 7.2, Pc < 0.005; DQB1*0402: OR = 9.2, Pc < 0.005; DQA1*0401: OR = 9, Pc < 0.02). In those subjects the DRB1*15 allele was less frequent than in controls (OR = 0.1, Pc = 0.05). By contrast, IDDM patients with no Ab showed no particular association with HLA class II allele although they had clinical and metabolic characteristics similar to that of Ab-positive subjects. The genetic basis for IDDM predisposition in the Ab-positive subgroup remains elusive since the DRB1*08-DQB1*0402 haplotype encodes an Asp57-positive DQβ chain. However, all DR8 patients had a non-Asp57 encoding DQB1 allele on the second haplotype. Thus, trans-complementation leading to peculiar predisposing DQβ heterodimers may occur. Alternatively, a direct role of the DRB1*08 allele cannot be excluded. These results show that autoimmune type 1 diabetes occurs in non-DR3/non-DR4 subjects, mainly adults. They further support that IDDM, when defined on a clinical basis, encompass different pathogenetic entities.     

Relative frequencies of DRB1*11 alleles and their DRB3 associations in five major population groups in a United States bone marrow registry

One hundred sixty-one individuals from each of five US population groups, Caucasians (CAU), African Americans (AFA), Asians/Pacific Islanders (API), Hispanics (HIS), and Native Americans (NAT), were randomly selected from a volunteer bone marrow registry database consisting of 14,452 HLA-DRB1*11 positive individuals. This sampling provided at least an 80% probability of detecting a rare allele that occurred at 1% in the DRB1*11 positive population. Samples were typed for DRB1*11 alleles by polymerase chain reaction-sequence specific oligonucleotide probe typing (PCR-SSOP). A total of 10 DRB1*11 alleles out of 27 possible alleles were detected. The distribution and diversity of DRB1*11 alleles varied among populations although DRB1*1101 was the predominant DRB1*11 allele in all populations. Caucasians were the least diversified; only four common alleles (DRB1*1101-*1104) were observed. As well as the four common alleles, other groups also carried one or two other less frequent alleles including DRB1*1105 (API), *1106 (API), *1110 (AFA), *1114 (HIS), *1115 (NAT), and *1117 (AFA). A subset (418) of these individuals were also typed for DRB3 alleles. Most (97.6%) showed a strong association of DRB1*11 with DRB3*0202.     

Association between IgE response against Bet v I, the major allergen of birch pollen, and HLA-DRB alleles.

The association of the human IgE response against bet v I, the major allergen of birch pollen, and the HLA-DR and DQ phenotype was studied. Birch pollen allergic patients showed a typical case history, positive skin-prick test, and positive RAST with birch pollen extracts. They were divided into two groups. Group I (n = 37) consisted of individuals generating IgE antibodies that selectively reacted with Bet v I. Their serum IgE did not react with minor allergens from birch pollen as tested by immunoblot analysis, nor did they show a response against allergens from a panel of grass and other tree pollen or perenial allergens from animals and fungi as determined by skin-prick test. Patients belonging to group II (n = 34) possessed IgE reacting with Bet v I plus one or more additional allergens. The control group consisted of 637 healthy blood donors. Comparison of the frequencies of RFLP-defined HLA-DR and DQ alleles in patients and the control group revealed that the distribution of DRB3 alleles in group I patients differed significantly from that in the control group: A higher frequency of the DRw52a/c alleles in comparison to the control group (P_corr < 0.02) was observed. In addition, alleles defined by nucleotide sequences coding for the amino acid sequence tyrosine-phenylalanine-histidine at positions 30–32 of the β chain of DR molecules were found with a higher frequency in patients group I(P_corr < 0.02), too. These alleles comprises DRw52a/c and some DRB1 alleles. In patients of group II, no significant differences in the distribution of class II alleles in comparison with the control group were observed. The fact that the association with DRB alleles is observed only in patients with a selective allergen-specific IgE response could mean that, among the genes that contribute to disease susceptibility, the class II genes play a more dominant role in these patients. In conclusion, certain allele encoded in DRB3 and DRB1 genes of the HLA compex might play a functional role in birch pollen allergy.     

MHC class I and class II phenotype, gene, and haplotype frequencies in Greeks using molecular typing data

In the present study, DNA typing for HLA-A, C, B, DRB1, DRB3, DRB4, DRB5, DQA1, DQB1, and DPB1 was performed for 246 healthy, unrelated Greek volunteers of 20-59 years of age. Phenotype, genotype frequencies, Hardy-Weinberg equilibrium fit, and 3-locus haplotype frequencies for HLA-A, C, B, HLA-A, B, DRB1, HLA-DRB1, DQA1, DQB1, and HLA-DRB1, DQB1, DPB1 were calculated. Furthermore, linkage disequilibrium, deltas, relative deltas and p-values for significance of the deltas were defined. The population studied is in Hardy-Weinberg equilibrium, and many MHC haplotypes are in linkage disequilibrium. The most frequent specificities were HLA-A*02 (phenotype frequency = 44.3%) followed by HLA-A*24 (27.2%), HLA-B*51 (28.5%), HLA-B*18 (26.8%) and HLA-B*35 (26.4%) and HLA-Cw*04 (30.1%) and HLA-Cw*12 (26.8%). The most frequent MHC class II alleles were HLA-DRB1*1104 (34.1%), HLA-DQB1*0301 (54.5%) and HLA-DPB1*0401 with a phenotype frequency of 59.8%. The most prominent HLA-A, C, B haplotypes were HLA-A*24, Cw*04, B*35, and HLA-A*02, Cw*04, B*35, each of them observed in 21/246 individuals. The most frequent HLA-A, B, DRB1 haplotype was HLA-A*02, B*18, DRB1*1104 seen in 20/246 individuals, while the haplotype HLA-DRB1*1104, DQB1*0301, DPB1*0401 was found in 49/246 individuals. Finally, the haplotype DRB1*1104, DQA1*0501, DQB1*0301 was observed in 83/246 individuals. These results can be used for the estimation of the probability of finding a suitable haplotypically identical related or unrelated stem cell donor for patients of Greek ancestry. In addition, they can be used for HLA and disease association studies, genetic distance studies in the Balkan and Mediterranean area, paternity cases, and matching probability calculations for the optimal allocation of kidneys in Greece.     

The set of naturally processed peptides displayed by DR molecules is tuned by polymorphism of residue 86

The response to tetanus toxoid (TT) was studied in immune donors that carry two alleles of DR5 that differ only at DRβ residue 86: DRB1*1101 (G86, abbreviated 1101) and DRB1*1104 (V86, abbreviated 1104). A large number of TT-specific T cell clones was isolated and the epitopes recognized in association with 1101 and 1104 were mapped. We found that two epitopes (p2 and p32) can be recognized in association with both 1101 and 1104 while three epitopes (p23, p27 and p30) are recognized in association with 1101, but never in association with 1104. The sets of naturally processed self peptides displayed by 1101 and 1104 were characterized using alloreactive T cell clones. We found that all 1104 alloreactive clones recognize both 1104 and 1101, while ?30% of the alloreactive 1101 clones fail to recognize 1104. Thus it is apparent that both naturally processed TTand self peptides displayed on 1104 molecules represent a fraction of those displayed on 1101 molecules. The mechanism responsible for this differential presentation was investigated by comparing the capacity of 1101 and 1104 antigen-presenting cells to present TTor synthetic peptides to specific T cells and by measuring the binding of these peptides to DR molecules. Three sets of results suggest that V86 acts as a constraint to the binding of naturally processed peptides: (i) all 1104-restricted or alloreactive T cell clones recognize TT- or allo-epitopes presented by 1101 as well, thus ruling out a major effect of V86 as a residue determining T cell restriction specificity; (ii) presentation of naturally processed peptides correlates in general with the capacity of long synthetic peptides to bind to 1101 or 1104 and (iii) while the naturally processed p30 epitope discriminates between 1101 and 1104, a short synthetic peptide binds equally well to and is comparably recognized in association with both 1101 and 1104. Taken together these results suggest that the natural polymorphism at residue 86 might be a molecular switch that finely tunes the complexity of the peptide collection presented on DR molecules.     

Strong linkage disequilibrium of TAP1*0301 and TAP2D alleles with the HLA A1-B35-DRB1*1104-DQA1*0103-DQB1*0603 extended haplotype in Ashkenazi Jews

On the basis of data collected during the 12th International Histocompatibility Workshop, we postulated a possible linkage disequilibrium between the TAP1C allele and the DRB1*1104-DQA1*0103-DQB1*0603 haplotype characteristic of Ashkenazi Jews. In order to confirm and extend this preliminary observation, a group of 34 subjects carrying this haplotype was analysed for TAP1 and TAP2 polymorphisms and compared with two control groups sharing either the DRB1 or the DQA1 and DQB1 alleles with the test group. The TAP1*0301 and TAP2D alleles were found to be strongly associated with the entire haplotype, but not with the DRB1*1104 or the DQA1*0103-DQB1*0603 alleles when carried separately. These data show a strong linkage disequilibrium of TAP1*0301 and TAP2D alleles with the DRB1*1104-DQA1*0103-DQB1*0603 haplotype of Ashkenazi Jews, extended on the centromeric and telomeric side to the DPB1*0201 and A1-B35 alleles, respectively.     

Strong linkage disequilibrium of TAP1*0301 and TAP2D alleles with the HLA A1-B35-DRB1*1104-DQA1*0103-DQB1*0603 extended haplotype in Ashkenazi Jews.

On the basis of data collected during the 12th International Histocompatibility Workshop, we postulated a possible linkage disequilibrium between the TAP1C allele and the DRB1*1104-DQA1*0103-DQB1*0603 haplotype characteristic of Ashkenazi Jews. In order to confirm and extend this preliminary observation, a group of 34 subjects carrying this haplotype was analysed for TAP1 and TAP2 polymorphisms and compared with two control groups sharing either the DRB1 or the DQA1 and DQB1 alleles with the test group. The TAP1*0301 and TAP2D alleles were found to be strongly associated with the entire haplotype, but not with the DRB1*1104 or the DQA1*0103-DQB1*0603 alleles when carried separately. These data show a strong linkage disequilibrium of TAP1*0301 and TAP2D alleles with the DRB1*1104-DQA1*0103-DQB1*0603 haplotype of Ashkenazi Jews, extended on the centromeric and telomeric side to the DPB1*0201 and A1-B35 alleles, respectively.