RECOMBINATION FRACTIONS IN THE HLA SYSTEM BASED ON THE DATA SET ‘PROVINCES FRANÇAISES’: INDICATIONS OF HAPLOTYPE-SPECIFIC RECOMBINATION RATES

In the large genetic survey ‘Provinces Françaises’ the recombination fractions in the HLA system have been estimated by a family analysis programme (FAP). A total of 1332 families were analysed and in general the findings were in agreement with recombination fractions reported previously. The maternal recombination rates were on average 1.8 times higher than the corresponding ones for males. The comparison of the recombination fractions with the corresponding physical distances suggests the existence of hot spots of recombination. The analysis did not show deviations from expected values for HLA-A and B alleles on HLA-A/B recombinant haplotypes. However, analysis of HLA-B/DR recombinant haplotypes showed a skewed distribution of B and DR alleles. The significance of the findings is difficult to evaluate as all results are estimated numbers and frequencies but a manual analysis of the recombinant families confirmed the observations. HLA-B/DR recombinant haplotypes carried often HLA-DR3 and DR11 whereas DR2 and DR7 were more rarely present on recombinant haplotypes. DR4 had an increased incidence on BF/DR recombinant haplotypes but not on A/B or B/BF recombinant haplotypes. Some of the haplotypes with the strongest linkage disequilibria as A1, B8, DR3 and A3, B7, DR2 seem to be less frequently involved in recombinations than other haplotypes. Variations of recombination rates depending on certain alleles or haplotypes might partially explain the conservation of some haplotypes or part of haplotypes in Caucasoids.     

The non‐inherited maternal HLA haplotype affects the risk for type 1 diabetes

The aim was to test the hypothesis that the human leucocyte antigen (HLA) haplotype that is not inherited from the mother, that is, the non‐inherited maternal antigen (NIMA) affects the risk for type 1 diabetes (T1D). A total of 563 children with T1D and 286 non‐diabetic control children from Sweden were genotyped for DRB1, DQA1 and DQB1 alleles. The frequency of positively (DR4‐DQA1*0301‐B1*0302 and DR3‐DQA1*0501‐B1*0201), negatively (DR15‐DQ A1*0102‐B1*0602) or neutrally (all other) T1D associated HLA haplotypes were compared between NIMA and non‐inherited paternal antigen (NIPA). All comparisons were carried out between HLA‐matched patients and controls. The frequency of positively associated NIMA was higher among both DR4/X‐positive healthy individuals compared wit DR4/X‐positive patients (P < 0.00003) and DR3/X‐positive healthy individuals compared with DR3/X‐positive patients (P < 0.009). No such difference was observed for NIPA. High‐risk NIMA was increased compared to NIPA among healthy DR3/X‐ and DR4/X‐positive children (P < 0.05). There was no difference in frequency of positively associated haplotypes between patient NIMA and NIPA. The NIMA but not the NIPA affects the risk for T1D, suggesting that not only the inherited but also non‐inherited maternal HLA haplotypes, perhaps through microchimerism or other mechanisms, may influence the risk for the disease.     

EXTENDED HLA-DQw2 HAPLOTYPES: MOLECULAR ANALYSIS

The HLA-DQw2 specificity, homogeneous in serology, is strongly associated to two HLA-DR specificities: DR3 and DR7. These alleles are found mainly on DQw2 bearing extended haplotypes with strong linkage disequilibrium. We describe, with BamHI, HindIII and RsaI, two restriction fragments length polymorphisms (RFLP) for the A gene of DQw2. These two subtypes correlated with the DR3 and DR7 specificities. Interestingly, by non-equilibrium pH gradient electrophoresis (NEPHGE), two DQα chains were also found, respectively correlated with the same DR specificities. In addition, Hindi polymorphism allowed us to distinguish several patterns of B genes for (DR7) DQw2 haplotypes but without any detectable association with another HLA marker. However, only one DQ(3 chain was found by NEPHGE in the (DR7) DQw2 haplotype. Furthermore, MncII discriminated the B genes of the two extended haplotypes: (B8, DR3) DQw2 and (B18, DR3) DQw2. The same result was found by NEPHGE: two DQβ chains were described, corresponding to the same extended haplotypes. The use of exon-specific DQB probes showed that the genomic polymorphism in DOw2 haplotypes is located, at least, at the 3’end of the gene. These data add new characteristics to the different DQw2 extended haplotypes.     

HLA Haplotype A33-B58-Cw10 May Modulate Radiographic Development of Bamboo Spine in Taiwanese Patients with Primary Ankylosing Spondylitis

Objective: To evaluate the possible relationship between HLA alleles and bony ankylosis of the spine (bamboo spine) in Taiwanese patients with ankylosing spondylitis (AS).Methods: A small cohort of HLA-B27 positive AS patients was conducted to analyze the effects of alleles and haplotypes on the development of bamboo spine. DNA typing of HLA class I and class II genes were performed by SSP method on primary ankylosing spondylitis patients with bamboo spine (n = 84) and spinal enthesopathy controls (n = 228). Odds ratios with 95% confidence intervals and P value were estimated. Determination of the most probable HLA haplotypes on all patients were constructed by comparison of the alleles carried by each patient with the HLA haplotype database established in Taiwanese population studies using homozygosity approach [1] and by expectation-maximum algorithm [2].Results: Allele frequencies of HLA A33, B58, Cw10, DR4, DR17 and DQ2 were significantly lower in bamboo patients as compared to non-bamboo controls. In contrast, allele frequencies of A24, B54, Cw15, DR11 and DR14 were significantly higher in bamboo patients. Less remarkably, high frequencies of B39, B51, Cw1 and Cw2 alleles were also noted in bamboo patients. Considering linkage disequilibria of alleles in haplotypes, HLA-A11-B27-Cw12 was the most common haplotype in both bamboo and non-bamboo groups (95.23% vs. 91.22%, respectively, P = 0.238). Haplotypes A33-B58-Cw10, A33-B58-Cw10-DR13 and A33-B58-Cw10-DR17 were significantly lower in bamboo patients as compared to those in controls (P < 0.001, P = 0.001, P = 0.002, respectively).Conclusion: Haplotypes A33-B58-Cw10, A33-B58-Cw10-DR13 and A33-B58-Cw10-DR17 showed a strong association with bamboo spine in Taiwanese AS patients. Detection of such haplotypes might be a great aid in the management of patients with the disease.     

Prevalence of human leukocyte antigen (HLA) DRB1 alleles in Kuwaiti children with juvenile rheumatoid arthritis

The prevalence of human leukocyte antigen (HLA) DR alleles has been determined in 69 Kuwaiti Arab children with juvenile rheumatoid arthritis (JRA) and compared to that in 212 ethnically matched normal healthy controls using a PCR–sequence specific primers (PCR‐SSP) method. A very high incidence of DR3 was detected in JRA patients compared to the controls (P < 0.0001, RR = 2.235). The high incidence of HLA‐DR3 in JRA patients was accounted for mainly by an excess of DRB1*0307 (P < 0.05, RR = 3.072) and DRB1*0308 (P < 0.009, RR = 2.663) compared to the controls. Moreover, DR3 was more prevalent when patients with ANA‐positive JRA were analysed separately; 73% compared to 58% for the whole JRA patient group. The frequency of DR1 was also higher in the JRA group compared to controls (P = 0.019, RR = 3.585). Although the incidence of some alleles was higher in the control group (DR13 and DR7), none reached a statistically significant level. All the patients with iridocyclitis had either a DR1 or DR3 allele, except for one child. The frequency of DRB1*03 was found to be much higher in the polyarticular subtype of Kuwaiti JRA cases compared to the oligoarticular subgroup and the controls. Also, a non‐significant increase in the frequency of the DRB1*04, *11 and *15 alleles was detected in the polyarticular subtype of the Kuwaiti JRA cases compared to the controls.     

HLA class II alleles: susceptibility or resistance to cystic echinococcosis in Yemeni patients

This is the first study dealing with the association between HLA alleles and cystic echinococcosis (CE) in Yemeni patients. The present study aimed to detect the association of HLA-DRB₁ alleles and susceptibility or resistance to CE in Yemeni patients by HLA-DRB₁ typing; first by HLA-DRB₁ amplification using PCR then using the allele-specific probing technique based on the reverse hybridization principle. This case–control study was carried out on 66 unrelated patients with confirmed CE and 66 apparently healthy individuals. The association of class II HLA-DRB alleles was examined in the patients with CE and compared with control subjects. Frequency of HLA-DR16 allele was 18.2% among patients and was statistically significant (higher) than in the control group [3%; odds ratio (OR) = 6.5, χ ² = 7.1, P = 0.011]. Frequencies of HLA-DR1, DR8, and DR52 alleles were decreased in the patient group (0.0%, 0.0%, and 56%, respectively) than in the control group (19.7%, 9.1%, and 74.2%, respectively) (OR = 0.0, 0.0, 0.443 and P < 0.0001, 0.04, 0.05, respectively). HLA-DR16 allele was found to be statistically positively associated with the occurrence of isolated hepatic CE, single cysts, and cysts >5 cm in size. In contrast, HLA-DR1 and DR52 alleles were found to be statistically negatively associated with the occurrence of isolated hepatic CE. This study demonstrates that susceptibility to CE in Yemeni patients is statistically significantly associated with the HLA-DR16 allele and resistance to CE is statistically significantly associated with HLA-DR1, DR8, and DR52 alleles. Thus, this study has identified that carriers of HLA-DR16 are at high risk for CE, so appropriate preventive measures and quick and careful treatment should be applied to those patients.     

The prevalence of HPA-1a alloimmunization and the potential risk of FNAIT depend on both the DRB3*01:01 allele and associated DR-DQ haplotypes

Alloimmunization against human platelet antigen (HPA)-1a during pregnancy can cause foetal/neonatal alloimmune thrombocytopenia (FNAIT) and severe bleeding in the foetus or newborn and likely depends on several factors. HPA-1a alloimmunization is associated with DRB3*01:01, which is associated with several DR-DQ haplotypes. However, it is not known to what extent these haplotypes contribute to the prevalence of HPA-1a alloimmunization. HPA-1a–alloimmunized women, identified in a prospective study, and random donors were typed for selected DRB3, DRB4, DRB1, DQA1 and DQB1 alleles to determine allele and DR-DQ haplotype frequencies. DRB3*01:01 was carried by 94% HPA-1a–immunized women compared to 27% in the general population. In the first population, the DR3-DQ2 haplotype was overrepresented (P < .003). The prevalence of HPA-1a alloimmunization was estimated to be about twice as frequent with DR3-DQ2 compared to DR13-DQ6, together accounting for about 90% of DRB3*01:01–positive individuals. Further, we examined DQB1*02 and DRB4*01:01 alleles for their reported association with HPA-1a alloimmunization, in the context of DR-DQ haplotypes. Since ~ 80% of DQB1*02 alleles are linked to the DR3-DQ2 haplotype, the association might be coincidental. However, the DQB1*02:02–associated DR7-DQ2 haplotype was also overrepresented in alloimmunized women, suggesting a role for this allele or haplotype in HPA-1a alloimmunization. As DRB4*01:01 is predominantly associated with the DR7-DQ2 haplotype in HPA-1a–alloimmunized individuals, the reported association with FNAIT may be coincidental. Typing for DR-DQ haplotypes revealed important genetic associations with HPA-1a alloimmunization not evident from typing individual alleles, and the presence of different DRB3-associated DR-DQ haplotypes showed different prevalence of HPA-1a alloimmunization.     

HLA-DRB3 gene alleles in Caucasian patients with Graves' disease

Summary Graves' disease (GD) is a human leukocyte antigen (HLA) linked organ-specific autoimmune disease. In German GD patients the disease is associated with HLA specificities of the HLA-DRw52 family (HLA-DR3, -DR5, and DR6; HLA-DRB3 positive HLA haplotypes). Recently, a strong association with a HLA-DRB3 restriction fragment length polymorphism gene has been described. To study HLA-DRB3 alleles and their association with the disease, a large cohort of controls (n = 3724) and GD patients (n = 304) was analyzed. HLA-DR allelic combinations revealed an increase in HLA-DR3/DR5 heterozygous patients (relative risk 2.9; P<0.001). HLA-DRB3 alleles, as defined by DNA typing in HLA-DR matched groups revealed a significant increase in DRB3^*0101 homozygosity (relative risk 17.5; P< 0.001) in HLA-DR3 homozygous patients. In GD patients with ophthalmopathy (grade II or higher, according to Werner) DRB3^*0101/^*0202 heterozygosity revealed an increased relative risk of 5.5 (P<0.001). Non-HLA-DR3 homozygous, DRB3^*0101/^*0202 heterozygous patients were at the highest risk for endocrine ophthalmopathy (relative risk 10; P<0.001). Our data, based on DNA typing methods of HLA-D genes, provide evidence that the susceptibility is strongly associated with HLA-DRB3 genes.Abbreviations EF etiological fraction - GD Graves' disease - HLA human leukocyte antigen - RR relative risk     

No independent association between a tumor necrosis factor-α promotor region polymorphism and insulin-dependent diabetes mellitus

Several studies have implicated tumor necrosis factor (TNF)-α in the pathogenesis of insulin-dependent diabetes mellitus (IDDM). In the present study we analyzed the first reported TNF-α gene polymorphism in relation to IDDM. We have made frequence analysis and tested in vitro lipopolysaccharide (LPS)-induced TNF-α secretion. A significant difference in allele frequency was observed between patients and controls (p = 0.03). However, a very strong association of the uncommonTNF2 allele was observed with the HLA-B8, –DR3 alleles. The relative risk (RR) of TNF2 was 2.2 compared to a RRof 3.1 for DR3. One reason for this difference was the identification of the TNF1 allele on the otherwise strongly IDDM-associated HLA-DR3 haplotype: DQB1*0201, DQA1*0501, DRB1*0301, TNFc2, TNFB*2, TNFal, TNFb5, B18. Thus, the IDDM-associated TNF2 allele had no DR3-independent value as a disease marker. The LPS-induced TNF-α production by human monocytes in relation to genotypes demonstrated that TNF1/2 heterozygous individuals had higher, though not statistically significantly (p = 0.08) levels than TNF1-homozygous subjects. However, this difference was rather small, unlikely to be of biological significance and based on the present material we cannot establish the functional importance of this polymorphism.     

Evidence of a strong, positive association between atopy and the HLA class II alleles DR4 and DR7

Background Atopy, with or without associated asthma, provides a useful model for evaluating the genetic factors that control human immune responsiveness. HLA class II gene products are involved in the control of immune responses. Objectives We investigated whether susceptibility or resistance to the disease was associated with HLA class II genes. Methods Blood samples were obtained from two groups of unrelated European-born white adults: 56 atopic patients (52 of them with asthma) and 39 healthy controls with no personal or familial history of asthma or atopy. Genomic DNA was extracted from peripheral blood lymphocytes. The exons of DQA1, DQB1, DRB and DPBl genes were selectively amplified by the polymerase chain reaction (PCR) method. Geno-typing was carried out by digestion of the amplified DNA products with allele-specific endonucleases (PCR-RFLP), which can recognize allelic variations in the polymorphic exon. Results We found no significant difTerences in the frequency of DPBl alleles between patients and controls. HLA class II DR4 and DR7 alleles were present in 39.2% of the patients and in 2.5% of the healthy subjects (Pc*²± 3.9 10^?3). Conversely, DQA1*0103 and DQB1*0502 alleles were more frequent in the control subjects. These results confirm a previous study of an extended pedigree, which showed that DR4 and DR7 alleles were absent in all healthy members of the family and were frequently observed in atopic and/or in asthmatic subjects. Conclusion We observed that HLA-DR 4 and DR7 alleles are significantly implicated in their susceptibility to the disease and suggest that this susceptibility is more related to atopy than to specific responses to allergens. According to previous studies, we could also submit that in atopic patients with asthma, DR4 alleles at the least, could be more closely associated with atopy than with asthma per se. Conversely, we suggest that some allelic DQA1 and DQB1 sequences might confer protection against the disease.     

HLA‐A,HLA‐B and HLA‐DRB1 allele and haplotype frequencies of 10 918 Koreans from bone marrow donor registry in Korea

The human leucocyte antigen (HLA) system is the most polymorphic genetic system in humans, and HLA matching is crucial in organ transplantation, especially in hematopoietic stem cell transplantation. We investigated HLA‐A, HLA‐B and HLA‐DRB1 allele and haplotype frequencies at allelic level in 10 918 Koreans from bone marrow donor registry in Korea. Intermediate resolution HLA typing was performed using Luminex technology (Wakunaga, Japan), and additional allelic level typing was performed using PCR–single‐strand conformation polymorphism method and/or sequence‐based typing (Abbott Molecular, USA). Allele and haplotype frequencies were calculated by direct counting and maximum likelihood methods, respectively. A total of 39 HLA‐A, 66 HLA‐B and 47 HLA‐DRB1 alleles were identified. High‐frequency alleles found at a frequency of ≥5% were 6 HLA‐A (A*02:01, *02:06, *11:01, *24:02, *31:01 and *33:03), 6 HLA‐B (B*15:01, *35:01, *44:03, *51:01, 54:01 and *58:01) and 8 HLA‐DRB1 (DRB1*01:01, *04:05, *04:06, *07:01, *08:03, *09:01, *13:02 and *15:01) alleles. At each locus, A*02, B*15 and DRB1*14 generic groups were most diverse at allelic level, consisting of 9, 12 and 11 different alleles, respectively. A total of 366, 197 and 21 different HLA‐A‐B‐DRB1 haplotypes were estimated with frequencies of ≥0.05%, ≥0.1% and ≥0.5%, respectively. The five most common haplotypes with frequencies of ≥2.0% were A*33:03‐B*44:03‐DRB1*13:02 (4.97%), A*33:03‐B*58:01‐DRB1*13:02, A*33:03‐B*44:03‐DRB1*07:01, A*24:02‐B*07:02‐DRB1*01:01 and A*24:02‐B*52:01‐DRB1*15:02. Among 34 serologic HLA‐A‐B‐DR haplotypes with frequencies of ≥0.5%, 17 haplotypes revealed allele‐level diversity and majority of the allelic variation was arising from A2, A26, B61, B62, DR4 and DR14 specificities. Haplotype diversity obtained in this study is the most comprehensive data thus far reported in Koreans, and the information will be useful for unrelated stem cell transplantation as well as for disease association studies.     

HLA class II susceptibility pattern for type 1 diabetes (T1D) in an Iranian population

This study aimed to determine the HLA‐DRB1/HLA‐DQB1 susceptibility and protection pattern for type 1 diabetes (T1D) in a population from Hamadan, north‐west of Iran. A total of 133 patients with T1D were tested for HLA‐DRB1 and HLA‐DQB1 alleles using PCR‐SSP compared to 100 ethnic‐matched healthy controls. Alleles and haplotypes frequencies were compared between both groups. The most susceptible alleles for disease were HLA‐DRB1*03:01, DRB1*04:02, DQB1*02:01 and DQB1*03:02, and protective alleles were HLA‐DRB1*07:01, *11:01, *13:01, *14:01 and DRB1*15 and HLA‐DQB1*06:01, *06:02 and *06:03. Haplotype analysis revealed that patients with T1D had higher frequencies of DRB1*03:01–DQB1*02:01 (OR = 4.86, P < 10^?7) and DRB1*04:02–DQB1*03:02 (OR = 9.93, P < 10^?7) and lower frequencies of DRB1*07:01–DQB1*02:01 (P = 0.0005), DRB1*11:01–DQB1*03:01 (P = 0.001), DRB1*13:01–DQB1*06:03 (P = 0.002) and DRB1*15–DQB1*06:01 (P = 0.001) haplotypes compared to healthy controls. Heterozygote combination of both susceptible haplotypes (DR3/DR4) confers the highest risk for T1D (RR = 18.80, P = 4 × 10^?5). Additionally, patients with homozygote diplotype, DR3/DR3 and DR4/DR4, showed a similar risk with less extent to heterozygote combination (P = 0.0004 and P = 0.01, respectively). Our findings not only confirm earlier reports from Iranians but also are in line with Caucasians and partly with Asians and some African patients with T1D. Remarkable differences were the identification of DRB1*04:01–DQB1*03:02, DRB1*07:01–DQB1*03:03 and DRB1*16–DQB1*05:02 as neutral and DRB1*13:01–DQB1*06:03 as the most protective haplotypes in this study.     

Cis-trans complementation of DQA1-DQB1 genes are modulated by DQ alleles: an immunogenetics analysis of DQ association with the down-regulatory function of CD8 cells in trichosanthin-induced immunosuppression

The initiation of a CD8 cell-mediated pathway (M⁺) was adopted as a phenotypic trait to analyse genetic predisposition in trichosanthin (Tk)-induced immunosuppression. Tk is a natural protein antigen with 247 amino acid residues. Based on DNA typing for DR, DQ, DP and TAP genes, data in this paper indicate that only DQ genes were primarily involved and that the alleles DQA1*0501 and DQB1*0201 were strongly associated with the M⁺ phenotype in cis (on DR3 haplotype) or trans (on DR5/DR7 heterozygotes) complementation. This is consistent with our observation that only the DQ-positive cells were capable of expanding after being co-cultured with Tk for 96h. Two points of interest were noted. (1) The susceptible haplotype DRB1*0301-DQA1*0501-DQB1*0201 showed an association with the M⁺ phenotype only if combined with DRB1*04-, DRB1*08-, or DRB1*09-related haplotypes. When co-presented with DRB1*11-, DRB1*15-, DRB1*07-related haplotypes, however, no cis complementation could be detected. A detailed analysis of the association patterns indicated that the DQB1 locus of the non-susceptible haplotypes was the main factor for up- or down-modulation. (2) For M⁺ phenotype-related trans complementation in Tk-induced suppression, it was found that not only DQA1*0501-DQB1*0201 (DR5/7) alleles, but also associated DQA1*0301-DQB1*0201 (DR4/7, 9/7) alleles, were involved. The allele DQB1*0201 was not associated with the DQA1 alleles in DRB1*01-, DRB1*15-, DRB1*13-, DRB1*07-related haplotypes. The results obtained indicate that there are some additional genetic factors involved in the functional expression of cis and trans complementation of DQA1 and DQB1 genes, among which the DQ alleles play a critical role as self-regulators.     

The in vitro response to human fibroplast-derived extracellular matrix proteins is restricted by specific HLA class II genes relevance for coeliac disease

Coeliac disease is an immunologic disease of the small intestine which is caused by ingestion of wheat gliadin, the disease-promoting agent. The disease associates strongly with the particular HLA type, HLA-DQA1^*0501, DQB1^*0201 alleles. Further specific auto-antibodies against reticulin and endomysium are found in patients; these autoantibodies appear to be disease specific. An extracellular matrix noncollagenous protein reacts specifically with CD patients' serum immunoglobulin A and is the target of antireticulin antibodies. In this study the immune response to this matrix protein was analyzed in vitro in normal, healthy individuals. Our study shows that the immune response to Fb-CDAP is strictly regulated by the HLA-DR3, DQA1^*0501, DQB1^*0201 alleles, and that only those cells which were positive for these alleles produced an immune response. On the other hand, half of the cells positive for these HLA alleles were responders. Monoclonal antibodies to DR and DQ inhibited the response in an additive way, showing that both DR and DQ can act as an antigen-presenting structure. The immune response to gliadin has been shown to associate with the same HLA type as CD, but the association is not as strong. Our results show that the immune response to Fb-CDAP can be generated in vitro in genetically predisposed persons in the absence of CD.     

Extended HLA haplotypes in families with insulin-dependent diabetes mellitus in Northern Finland

Haplotypes including HLA, Bf and C4 loci were analyzed in a material comprising 55 families with diabetic children. One hundred and ten haplotypes found in IDDM patients were compared with 101 haplotypes present only in healthy family members. Two complotypes, BfSC4A3B3 and SC4A0B1 . were significantly more common (P <0.05) in the diabetic haplotypes, and these were in most cases found in haplotypic combinations with HLA-B15,Dw4,DR4 and HLA-B8.Dw3,DR3 genes, respectively. The B8/DR3 haplotype was better conserved, as 72% included the BfSC4A0B1 complotype as compared with only 35% of the B15/DR4 haplotypes with "high risk" C4A3B3 complement alleles (p <0.05). DR3 was found in 26% of the diabetic haplotypes and DR4 in 43%. DR4 associated with the Dw4 in 69% of cases and with D w14 in 26% of the diabetic haplotypes. Our results confirm that the two phenotypes found earlier to be associated with IDDM in Northern Finland, e.g. "B15, BfS, C4A3B3, Dw4, DR4" and "B8, BfS, C4A0B1, Dw3, DR3" are inherited as haplotypes.     

ANALYSIS OF HLA HAPLOTYPES IN FAMILIES WITH TYPE 1 DIABETES MELLITUS IN LA RÉUNION ISLAND

To analyse HLA and insulin-dependent diabetes mellitus (IDDM) association in the ethnically mixed population of La Réunion island, we carried out a family study on 70 diabetic subjects. HLA-DQA1, -DQB1 and -DRB1 typing was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), completed by PCR-sequence-specific oligonucleotide (SSO) and PCR-sequence-specific priming (SSP). Haplotype-relative risks (HRR) were determined with the non-transmitted parental haplotypes as controls, and relative risks (RR) were calculated with a classical case-control study. The most significant risks were found for the cis and trans combinations between DQA1*03 or *0501 (Arg52⁺) and DQB1*02 or *0302 (Asp57^?) alleles, suggesting a direct role for the HLA-DQ heterodimer in IDDM susceptibility. Interestingly, due to the mixed origin of the population, the trans-encoded DQ molecules in the (DR3)-DQA1*0501-DQB1*02/(DR4)-DQA1*03-DQB 1*0302 subjects were also found cis-encoded in patients with the (DR7 or 9)-DQA1*03-DQB1*02 haplotype and in a patient with the rare (DR 11)-DQA1*0501-DQB 1*0302 haplotype. A relative predispositional effect (RPE) analysis gave significant haplotype-IDDM⁺ associations in the following order: (DR3)-DQA1*0501-DQB1*02>(DR4)-DQA1*03-DQB1*0302>(DR9)-DQA1*03-DQB*02>(DR7)-DQA1*03-DQB1*02>(DR2)-DQA1*01-DQB1*0502. No protective effect remained significant once the susceptible haplotypes were removed. A stratification study showed a stronger influence of the DQ genes than DRB1 alleles within the DR7 haplotypes. On the other hand, IDDM subjects with only one susceptible haplotype had inherited this haplotype more often from their father than from their mother. This paternal effect could be related to the greater risk of IDDM in offspring of diabetic fathers than the risk in offspring of diabetic mothers.     

B-cell epitopes recognized by IgE from patients sensitive to Amb a 5

Background The response to allergens characterized hy IgE-mediated hypersensitivity is selective. The search for the inherited contribution to atopy has among other things, focused on the linkage of sensitivity to the presence of specific alleles in the DR and DQ locus. More than 90% of the responders to Amb a 5, an allergen from ambrosia artemisifolia, are DR-2 positive. This relationship is logically linked to the T-cell epitope presentation by the HLA complex. Objectives This study aims to investigate a possible relationship between T-cell epitopes. B-cell epitopes and the alleles of the DR and DQ loci in Amb a 5 sensitive DR-2+ and DR-2 – individuals. Methods Inhibition of solid state Elisa assays by IgE-enriched and IgG-depleted, heated sera. The inhibition was carried out in checkerboard pattern, bidirectionally; A inhibits B and B inhibits A. Results The B-cell epitopes defined hy the inhibition pattern were all found to be conformational. Three different epitope patterns (A, B, C) were recognized. The IgE and IgG complexes were found in only one responder. The DR and DQ locus alleles were all sequenced. Although all the individuals studied responding to Amb a 5 show presence of alleles such as 1501, associated with DR-2, our data indicates no correlation between the B-cell epitopes recognized and the DR and DQ locus alleles. A well known, general T-cell motif was recognized in the known sequence of Amb a 5. Conclusions Our investigation suggests that the choice of B-cell recognition is regulated independently of a putative link between T-cell epitope recognition and the D locus.     

FREQUENCIES OF HLA-A24 AND HLA-DR4-DQ8 ARE INCREASED AND THAT OF HLA-B BLANK IS DECREASED IN CHRONIC TOXIC OIL SYNDROME

The cause of toxic oil syndrome (TOS) has not yet been definitively determined, but some genetic susceptibility factors (certain HLA antigens and female sex) have been identified in 236 patients. Similarities with genetic factors for scleroderma and hydralazine-induced lupus (i.e. in TOS female sex and HLA-A24, P_corrected= 0.00001 and DR4, P_corrected= 0.04, respectively) may provide a clue to the responsible xenobiotic and its pathogenesis, and may also help in understanding the basis of the related eosinophilia-myalgia syndrome associated with tryptophan ingestion. In this paper it is also established that a human class I antigen (HLA-A24) and, independently, an HLA class II haplotype (DR4-DQ8, P_corrected= 0.04) and arginine 52 in the α-DQ chains (P_corrected= 0.03) are associated with TOS susceptibility, similarly to insulin-dependent diabetes. This further supports the classification of TOS as an autoimmune disease. Also, the increased frequency of a particular set of low-frequency HLA class I antigens in chronic TOS patients (i.e. B27, B37, B38 and B49) and the probable decrease in the frequency of HLA-B homozygotes in surviving patients (P_corrected= 0.008) may provide an objective model to explain the maintenance of the HLA polymorphism: less frequent HLA alleles may be more advantageous in the event of unexpected human contact with unusual xenobiotics (not only microbes); however, other mechanisms working together to preserve and generate HLA polymorphism may coexist.     

HLA class II (DRB1, DQA1 and DQB1) associated genetic susceptibility in Iranian multiple sclerosis (MS) patients

The association of HLA class II alleles with multiple sclerosis (MS) has been amply documented. In the present study, the role of HLA class II (DRB1, DQA1 and DQB1) alleles and haplotypes was investigated in 43 unrelated Iranian chronic progressive multiple sclerosis (CP-MS) patients compared with 100 healthy individuals. HLA typing for DRB1, DQA1 and DQB1 was performed by restriction fragment length polymorphism (RFLP). Subtypes of DR4, DR15 and DR16 were defined using polymerase chain reaction (PCR) amplification with sequence-specific primers (PCR-SSP). The results show that, among DR2-positive MS patients and the control group, a positive association with the DRB1*1503, DQA1*0102, DQB1*0602 haplotype (21% vs. 2.7%, P=0.057, RR=9.8) and a negative association with the most frequent DR15 haplotype in the control group, DRB1*15021, DQA1*0103, DQB1*0601 (7% vs. 24.3%, P=0.001), were observed. No significant association was found with the analysed HLA-DRB1, DQA1 and DQB1 alleles.     

Analysis of TACI mutations in CVID & RESPI patients who have inherited HLA B*44 or HLA*B8

Background  

Recent reports have suggested that Common Variable Immunodeficieny (CVID) can present as an autosomal dominant trait dependent on the inheritance of a set of uncommon mutations/alleles of TACI (transmembrane activator and calcium-modulator and cyclophilin ligand interactor) involving exons 3 or 4. Penetrance, however, appears to be incomplete. Among our clinic population, the greatest genetic linkage for CVID is to the major histocompatibility complex (MHC) on chromosome 6. The majority of our patients have inherited HLA *DQ2, *DR7, *DR3(17), *B8, and/or *B44. Of these, HLA*B44 was present in almost half of the patients and was thus the most common susceptibility allele. HLA *B44 was also found to be over-represented among patients who presented to our clinic with adult-onset recurrent sinopulmonary infections (RESPI) and normal serum immunoglobulin levels, a cohort that included first and second degree relatives of patients with CVID. One of the two original reports of the association between TACI and CVID also reported Human Leukocyte Antigen (HLA) haplotypes. Of 13 affected subjects, nine had inherited HLA *B8 and six had inherited HLA B44. This raised the possibility that TACI mutations might synergize with MHC class I alleles to enhance susceptibility to humoral immune deficiency.