DQB1 Loci Research Articles

Human leukocyte antigen genotypes in the genetic control of adaptive immune responses to smallpox vaccine.

The role of human leukocyte antigen (HLA) genes in mediating adaptive immune responses to smallpox vaccine remains unknown. We determined genotypes for a group of individuals (n = 1071) who received a single dose of smallpox vaccine (Dryvax, Wyeth Laboratories) and examined associations between HLA alleles and 15 immune outcomes to smallpox vaccine on a per-locus and a per-allele level. We found significant associations between the HLA-B and HLA - DQB1 loci and vaccinia-induced antibodies (P = .04 for each locus), with the HLA-B*1302 (P = .036), B*3802 (P = .011), DQB1*0302 (P = .015), and DQB1*0604 (P = .017) alleles being associated with higher levels. Significant global associations were identified between vaccinia-specific interferon (IFN)-γ and DQA1 (P = .003), interleukin (IL)-1β and HLA-B (P = .004), tumor necrosis factor (TNF)-α and HLA-B (P = .006), and IL-6 and HLA-B locus (P = .016) for secreted cytokines, as well as between CD8α(+) IFN-γ Elispot responses and DQB1 (P = .027). Subjects carrying B*3906 (P = .006) and B*5701 (P < .001) secreted higher levels of IL-1β than did subjects who did not carry these alleles. Subjects carrying the B*5301 (P = .047) and B*5601 (P = .008) alleles secreted less IL-1β, compared with subjects who did not carry these alleles. The B*3502 (P = .009), B*5601 (P = .004), and B*5701 (P < .001) alleles were significantly associated with variations in TNF-α secretion. These data suggest that variations in antibody and cellular IFN-γ, IL-1β, TNF-α, and IL-6 immune responses after receipt of smallpox vaccine are genetically controlled by HLA genes or genes in close linkage disequilibrium to these alleles.

SLA‐DRB1 and ‐DQB1 genotyping by the PCR–SSOP–Luminex method

A simple and novel genotyping method was developed to detect alleles at the swine leukocyte antigen (SLA)-DRB1 and -DQB1 class II loci by using polymerase chain reaction (PCR)-fluorescently labeled sequence-specific oligonucleotide probes (SSOPs) and Luminex 100 xMAP detection. The PCR-SSOP-Luminex method exhibited accuracy of 95% for both SLA-DRB1 and -DQB1 in 6 homozygous and 16 heterozygous pig samples as confirmed by sequencing the PCR products of the same samples. In addition, 12 low-resolution SLA class II haplotypes consisting of 7 and 9 DRB1 and DQB1 alleles were identified, respectively, in one population of 283 Landrace pigs. This genotyping method facilitates the rapid and accurate identification of two- or four-digit alleles at the SLA-DRB1 and -DQB1 loci.

Study of the HLA class II allele polymorphism and phylogenetic analysis in Vojvodina population

The polymorphism at the HLA DRB1 and DQB1 loci in the population of Vojvodina was studied by PCR-SSP method. A total of 13 DRB1 and 5 DQB1 specificities displaying population-specific frequency distribution pattern were described. The most frequent HLA Class II alleles in Vojvodina population were: HLA-DRB1*11 (af = 0.30), -DRB1*04 (af = 0.28), -DRB1*07(af = 0.21), -DRB1*13 and -DRB1*16 (af = 0.18), -DQB1*03 (af = 0.64), -DQB1*05 (af = 0.39) and -DQB1*02 (af = 0.35). The haplotypes with high frequencies (> or = 0.02) included HLA DRB1*11 DQB1*03 (0.0825), DRB1*04DQB1*03 (0.0725), DRB1*07DQB1*02 (0.0475). The allele DRB1*07 showed the strongest association with DQB1*02 (delta = 0.0261, chi2 = 4.437) and DRB1*13 allele with DQB1*06 (delta = 0.0222, chi2 = 4.247). The allelic frequencies and populations distance dendrogram revealed the closest relationship of Vojvodina population with Hungarians, Croat, and Greeks which can be the result of turbulent migration within this region and admixture with neighbour populations during the history.

Polymorphism and gene organization of water buffalo MHC‐DQB genes show homology to the BoLA DQB region

In cattle (Bos taurus), there is evidence of more than 50 alleles of BoLA-DQB (bovine lymphocyte antigen DQB) that are distributed across at least five DQB loci, making this region one of the most complex in the BoLA gene family. In this study, DQB alleles were analysed for the water buffalo (Bubalus bubalis), another economically important bovine species. Twelve alleles for Bubu-DQB (Bubalis bubalis DQB) were determined by nucleotide sequence analysis. A phylogenetic analysis revealed numerous trans-species polymorphisms, with alleles from water buffalo assigned to at least three different loci (BoLA-DQB1, BoLA-DQB3 and BoLA-DQB4) that are also found in cattle. These presumptive loci were analysed for patterns of synonymous (d(S)) and non-synonymous (d(N)) substitution. Like BoLA-DQB1, Bubu-DQB1 was observed to be under strong positive selection for polymorphism. We conclude that water buffalo and cattle share the current arrangement of their DQB region because of their common ancestry.

HLA allele frequencies in Iranian opticospinal multiple sclerosis patients&amp;lt;br&amp;gt;——HLA in Opticospinal MS

Background: In Iranian patients with opticospinal multiple sclerosis (OSMS), a paucity of brain lesions and short spinal cord lesions extending less than three spinal segments are characteristic findings on magnetic resonance imaging (MRI). It also shows a relatively benign course with negative CSF oligo-coonal bands. Objective: We aimed to clarify the possible relationship between clinical phenotype and MRI features of OSMS and human leucocyte antigen (HLA) system in Iran. Methods: Genotyping of HLA class II allele frequencies in 20 patients with OSMS were done, using polymerase chain reaction sequence-specific primer amplification method. Blood samples were extracted and typed for HLA-DRB, DQA, and DQB loci and compared with 100 controls. Results: Significant positive association was observed in DRB1*03, DQA1*0201, DQA1*03, DQB1*0201, and DQB1*0611, while DQB1*0602 was absent in our patients. Conclusion: These finding suggest that HLA-DRB association pattern in OSMS is different from conventional MS in Iran which is mostly associated with DRB1*1501 and from similar Japanese OSMS who are negative for brain lesions fulfilling the Barkhof criteria and negative for the presence of longitudinally extensive spinal cord lesions who carries the DRB*0405 allele. OSMS is immunogenetically heterogeneous. Also absence of DQB1*0602 allele may negatively be associated with the absence of Barkhof brain lesion.

Characterization of the major histocompatibility complex class II DOB, DPB1, and DQB1 alleles in cynomolgus macaques of Vietnamese origin

Major histocompatibility complex (MHC) molecules play an important role in the susceptibility and/or resistance to many diseases. To gain an insight into the MHC background and to facilitate the experimental use of cynomolgus macaques, the second exon of the MhcMafa-DOB, -DPB1, and -DQB1 genes from 143 cynomolgus macaques were characterized by cloning to sequencing. A total of 16 Mafa-DOB, 16 Mafa-DPB1, and 34 Mafa-DQB1 alleles were identified, which revealed limited, moderate, and marked allelic polymorphism at DOB, DPB1, and DQB1, respectively, in a cohort of cynomolgus macaques of Vietnamese origin. In addition, 16 Mafa-DOB, 5 Mafa-DPB1, and 8 Mafa-DQB1 alleles represented novel sequences that had not been reported in earlier studies. Almost of the sequences detected at the DOB and DQB1 locus in the present study belonged to DOB*01 (100%) and DQB1*06 (62%) lineages, respectively. Interestingly, four, three, and one high-frequency alleles were detected at Mafa-DOB, -DPB1, and -DQB1, respectively, in this monkeys. The alleles with the highest frequency among these monkeys were Mafa-DOB*010102, Mafa-DPB1*13, and Mafa-DQB1*0616, and these were found in 33 (25.6%) of 129 monkeys, 32 (31.37%) of 102 monkeys, and 30 (31%) of 143 monkeys, respectively. The high-frequency alleles may represent high priority targets for additional characterization of immune function. We also carried out evolutionary and population analyses using these sequences to reveal population-specific alleles. This information will not only promote the understanding of MHC diversity and polymorphism in the cynomolgus macaque but will also increase the value of this species as a model for biomedical research.

Sequence analysis of the grey mouse lemur (Microcebus murinus) MHC class II DQ and DR region

We here report the genomic organisation of the grey mouse lemur (Microcebus murinus) MHC class II DQ and DR region based on BAC clone analysis. The sequenced Mimu-MHC haplotype spans 343kb and encompasses the genes TAP2, DOB, DQB, DQA, DRB, DRA, BTNL2 and a further BTNL gene. The DQ and DR genes of this haplotype are not duplicated. Mimu-DOB is not transcribed and represents a pseudogene due to deletions and premature stop codons. Analysis of BAC clone DNA, a cDNA sample and eight genomic DNA samples suggests that Mimu-DRB, Mimu-DQA and Mimu-DQB are highly polymorphic with the majority of peptide-binding residues being affected by polymorphisms. In contrast, Mimu-DRA is moderately polymorphic, and the variable amino acid positions are not part of the peptide-binding region. Phylogenetic analysis of Mimu-DQA and Mimu-DQB and other primate DQA and DQB genes indicates that duplication of DQA and DQB loci occurred in Anthropoidea after the split from Strepsirrhini.

Association of HLA Class II alleles and haplotypes with cervical dystonia: HLA DR13-DQ6 (DQB1*0604) homozygotes are at greatly increased risk of cervical dystonia in Caucasian Americans

An unanticipated discovery was made while examining genetics of the immune response in patients treated with botulinum neurotoxin (BoNT), which included cervical dystonia (CD) patients. Initial examination of HLA DQA1:DQB1 frequencies revealed an unexpectedly high number of DQA1*0102:DQB1*0604 homozygotes (hz) in the CD patients. We typed the BoNT-treated CD Caucasian subset for HLA-DRB1, DQA1, and DQB1 and succeeded in typing HLA-DRB1, -DQA1, and -DQB1 for 75 of the patients. Two statistical methods found the DQB1 locus associated with CD and one method found a probable association of DQB1*0604. Examination of the allele and haplotype pairing indicated that DQB1*0604 hz comprised most to all of the positive association. Other than this genotype, one other allele, DQB1*0504 contributes to the association of the DQB1 locus. These findings indicate a probable infectious and/or autoimmune component in some CD patients. However, longer distance associations within an extended and conserved DQB1*0604 bearing haplotype leave a possibility that a locus proximal to DQB1 might be involved.

Allelic diversity at MHC class II DQ loci in buffalo ( Bubalus bubalis): Evidence for duplication

The genetic diversity of MHC class II DQ genes was investigated in riverine buffalo ( Bubalus bubalis) by PCR-RFLP and sequencing. Highly variable regions (exons 2–3) of DQ genes were amplified from 152 buffaloes and genotyped by PCR-RFLP. Alleles identified by differential restriction patterns were sequenced for the characterization. PCR-RFLP was a rapid method to discriminate between DQA1 and duplicated DQA2 genes in buffalo, however, the method appeared to be inadequate for determining the more complicated DQB genotypes. A total of 7 and 10 alleles were identified for DQA and DQB loci, respectively. Nucleotide as well as amino acid variations among DQ alleles particularly at peptide binding regions were high. Such variations were as expected higher in DQB than DQA alleles. The phylogenetic analysis for both genes revealed the grouping of alleles into two major sub-groups with higher genetic divergence. High divergence among DQ allelic families and the isolation of two diverse DQA and DQB sequences from individual samples indicated duplication of DQ loci was similar in buffalo to other ruminants.

Molecular characterization of swine leucocyte antigen class II genes in outbred pig populations

The highly polymorphic swine leucocyte antigen (SLA) genes are among the most important determinants of swine immune responses to disease and vaccines. Accurate and effective SLA genotyping methods are required to understand how SLA gene polymorphisms affect immunity, especially in outbred pigs with diverse genetic backgrounds. In this study, we present a simple and rapid molecular-based typing system for characterizing SLA class II alleles of the DRB1, DQB1 and DQA loci. This system utilizes a set of 47 sequence-specific PCR primers developed to differentiate alleles by groups that share similar sequence motifs. We applied this typing method to investigate the SLA class II diversity in four populations of outbred pigs (n = 206) and characterized a total of 19 SLA class II haplotypes, six of which were shared by at least three of the sampled pig populations. We found that Lr-0.1 (DRB1*01XX-DQB1*01XX-DQA*01XX) was the most prevalent haplotype with a combined frequency of 16.0%, followed by Lr-0.2 (DRB1*02XX-DQB1*02XX-DQA*02XX) with 14.6% and Lr-0.15b (DRB1*04XX-DQB1*0202-DQA*02XX) with 14.1%. Over 70% of the pigs (n = 147) had at least one copy of one of these three haplotypes. The PCR-based typing system described in this study demonstrates a reliable and unambiguous detection method for SLA class II alleles. It will be a valuable tool for studying the influence of SLA diversity on various immunological, pathological and physiological traits in outbred pigs.

Analysis of maternal–offspring HLA compatibility, parent‐of‐origin effects, and noninherited maternal antigen effects for HLA–DRB1 in systemic lupus erythematosus

Genetic susceptibility to systemic lupus erythematosus (SLE) is well established, with the HLA class II DRB1 and DQB1 loci demonstrating the strongest association. However, HLA may also influence SLE through novel biologic mechanisms in addition to genetic transmission of risk alleles. Evidence for increased maternal-offspring HLA class II compatibility in SLE and differences in maternal versus paternal transmission rates (parent-of-origin effects) and nontransmission rates (noninherited maternal antigen [NIMA] effects) in other autoimmune diseases have been reported. Thus, we investigated maternal-offspring HLA compatibility, parent-of-origin effects, and NIMA effects at DRB1 in SLE. The cohort comprised 707 SLE families and 188 independent healthy maternal-offspring pairs (total of 2,497 individuals). Family-based association tests were conducted to compare transmitted versus nontransmitted alleles (transmission disequilibrium test) and both maternally versus paternally transmitted (parent-of-origin) and nontransmitted alleles (using the chi-square test of heterogeneity). Analyses were stratified according to the sex of the offspring. Maternally affected offspring DRB1 compatibility in SLE families was compared with paternally affected offspring compatibility and with independent control maternal-offspring pairs (using Fisher's test) and was restricted to male and nulligravid female offspring with SLE. As expected, DRB1 was associated with SLE (P < 1 x 10(-4)). However, mothers of children with SLE had similar transmission and nontransmission frequencies for DRB1 alleles when compared with fathers, including those for the known SLE risk alleles HLA-DRB1*0301, *1501, and *0801. No association between maternal-offspring compatibility and SLE was observed. Maternal-offspring HLA compatibility, parent-of-origin effects, and NIMA effects at DRB1 are unlikely to play a role in SLE.

Familial Recurrent Hypersomnia: Two Siblings with Kleine-Levin Syndrome and Menstrual-Related Hypersomnia

Kleine-Levin syndrome and menstrual-related hypersomnia are rare idiopathic sleep disorders occurring primarily in adolescence. They are characterized by intermittent periods of excessive sleepiness, cognitive disturbances, and behavioral abnormalities. In both, the etiology remains unknown but autoinmune, hormonal, infectious, and inflammatory mechanisms have been proposed. The authors describe, for the first time, the association of Kleine-Levin syndrome and menstrual-related hypersomnia in 2 adolescent siblings who shared the human leukocyte antigen (HLA) loci DQB1*0501. The same haplotype has been associated with sleepwalking and with rapid eye movement (REM) sleep behavior disorder. This gender differences in the manifestation of a probably genetic influenced sleep disorder suggests that hormonal mechanisms could be implicated in the phenotypical expression of this sleep disorder. The male sibling with Kleine-Levin syndrome was easily controlled with carbamazepine in low doses, but his sister could be only efficaciously treated with oral contraceptives.

Increased genetic risk or protection for canine autoimmune lymphocytic thyroiditis in Giant Schnauzers depends on DLA class II genotype

Dogs represent an excellent comparative model for autoimmune thyroiditis as several dog breeds develop canine lymphocytic thyroiditis (CLT), which is clinically similar to Hashimoto's thyroiditis in human. We obtained evidence that dog leukocyte antigen (DLA) class II genotype function as either genetic risk factor that predisposes for CLT or as protective factor against the disease. Genetic diversity at their DLA-DRB1, -DQA1, and -DQB1 loci were defined and potential association to major histocompatibility complex II haplotypes and alleles was analyzed. Giant Schnauzers carrying the DLA-DRB1*01201/DQA1*00101/DQB1*00201 haplotype showed an increased risk (odds ratio of 6.5) for developing CLT. The same risk haplotype has, to date, been observed in three different breeds affected by this disease, Giant Schnauzer, Dobermann, and Labrador Retriever, indicating that it is a common genetic risk factor in a variety of breeds affected by this disease. Importantly, protection for development of the disease was found in dogs carrying the DLA-DRB1*01301/DQA1*00301/DQB1*00501 haplotype (odds ratio of 0.3).

Molecular identification of the HLA-DRB1-DQB1 for diagnosis and follow-up of acute leukemias

We analyzed a group of 45 Brazilian individuals, 30 with acute myeloid leukemia (AML), 15 with acute lymphoid leukemia (ALL) and 100 healthy controls to assess genetic factor risk and HLA association contribution to the disease. Patient rates were compared with age and sex-matched control groups by directly typing the HLA-DRB1/3/4/5 and -DQB1 loci by PCR analysis. We observed significantly increased allelic distribution of HLA-DRB1⁎07 in AML patients and of HLA-DRB1⁎03 in ALL patients, which suggests that individuals in both groups are susceptible to the disease. We also found significantly decreased allelic distribution of HLA-DQB1⁎04 in AML patients and of HLA-DRB1⁎04 and -DQB1⁎03 in ALL patients, which suggests protection against the disease. We further found increased HLA-DRB1⁎07 and -DQB1⁎02 haplotypes in AML patients, which suggests susceptibility to the disease and decreased HLA-DRB1⁎04 and -DQB1⁎03 haplotypes in ALL patients, which also suggests protection against the disease. Future studies with larger and/or multicentric samples will be required for better comprehension of the HLA role in acute leukemia pathogenesis.

Identification of the expressed MHC class II DQB gene of the Asiatic black bear, Ursus thibetanus, in Japan

Genetic diversity estimation of the major histocompatibility complex (MHC) gene may be an important tool in the assessment of immune response ability against infectious disease. We were able to identify a near full-length expressed DQB sequence by RACE-PCR method from the Asiatic black bear, Ursus thibetanus in Japan. This is the first such full length expression in the Ursidae. The bear had at least one functional DQB locus. In phylogenetic tree analysis its DQB amino acid sequence formed a monophyletic group with DQB sequences from members of the order Carnivora and had a 90% nucleotide sequence similarity with the DQB allele of the California sea lion, Zalophus californianus. We compared the DQB amino acid composition of U. thibetanus with those of several other mammalian species including Homo sapiens. Amino acid residues known to be functionally important for human MHC genes, tended to be also conserved among other mammalian species while PBRs in the beta1 domain were heterogeneous among mammalian species. The DQB sequence obtained from the bear had not only no putative frameshifts or deletions but also no abnormal amino acid mutations such as had been observed in human DQB molecules. This suggests that the bear DQB sequence was an apparently functional DQB allele. As a preliminary study, we sequenced the exon 2 region of DQB alleles from genomic DNA, and succeeded to amplify the exon 2 of DQB loci. Our study will provide useful information for conservation genetics of the U. thibetanus as well as more generally regarding the mammalian MHC region.

Norwegian Sami differs significantly from other Norwegians according to their HLA profile

This study reports extensive genomic data for both human leukocyte antigen (HLA) class I and II loci in Norwegian Sami, a native population living in the northwest of Europe. The Sami have a distinct culture and their own languages, which belong to the Uralic linguistic family. Norwegian Sami (n = 200) were typed at the DNA level for the HLA-A, -C, -B, -DRB1 and -DQB1 loci, and compared with a non-Sami Norwegian population (n = 576). The two populations exhibited some common genetic features but also differed significantly at all HLA loci. The most significantly deviating allele frequencies were an increase of HLA-A*03, -B*27, -DRB1*08 and -DQB1*04 and a decrease of HLA-A*01, C*01, -DRB1*04 and -DQB1*02 among Sami compared with non-Sami Norwegians. The Sami showed no deviation from Hardy-Weinberg equilibrium. The hypothesis of selective neutrality was rejected at all loci except for the A- and C- loci for the Sami. HLA haplotype frequencies also differed between the two populations. The most common extended HLA haplotypes were A*02-B*27-C*01-DR*08-DQB1*04 in the Sami and A*01-B*08-C*07-DR*03-DQB1*02 in the other Norwegians. Genetic distance analyses indicated that the Norwegian Sami were highly differentiated from other Europeans and were most closely related to Finns whose language also belongs to the Uralic linguistic family. In conclusion, the Norwegian Sami and the non-Sami Norwegians were significantly different at all HLA loci. Our results can be explained by the fact that the two populations have different origins and that the Sami population has remained smaller and more isolated than its neighbors.

Impact of Minor Histocompatibility Antigens (mHAg) Mismatches On Gvhd Incidence in Non-Myeloablative or Reduced Intensity Allogeneic Stem Cell Transplantation.

Abstract 4494 1.BackgroundMismatches of minor Histocompatibility antigens (mHAg) have been considered as an important immunogenetic factor influencing outcomes and immune responses following allogeneic stem-cell transplantation (alloSCT) despite fully matched HLA of donor and recipient. 2. AimAim of this study was to assess whether mHAg incompatibilities may affect overall survival (OS), progression free survival (PFS) and GVHD incidence (acute and chronic, aGVHD and cGVHD) in patients receiving alloSCT for lymphoid malignancies. 3. MethodsSixty-four consecutive patients with B-cell lymphomas who underwent alloSCT were studied. Ten patients had chronic lymphocytic leukemia (CLL, 15.8%), 3 had follicular lymphoma (FCL, 4.7%), 1 had diffuse large B cell lymphoma (DLBCL, 1,5%), 17 had Hodgkin's lymphoma (26.5%) and 33 had multiple myeloma (51.5%). All underwent peripheral blood stem-cells allograft with non-myeloablative (13 patients, 20%) or reduced intensity (51 pts, 80%) Fludarabine-based conditioning; GVHD prophylaxis included methotrexate and oral cyclosporine +/- micomofetil fenolate in case of matched unrelated donors. Median age was 51 years (range 18-66); 35 patients were male (55%), median number of previous chemotherapies was 3 (0-7), 49 patients had a previous autologous transplant (76%). Twenty-five patients were in complete remission (CR, 39%), 30 and 9 were in partial response and progression (PR 47% and PD 14%). Karnofsky performance status (PS) was >80% in 50 patients (78%). Forty-four patients allografted from HLA-matched siblings (69%), 20 from matched unrelated donor (31%): all were matched at allelic level for HLA-A, -B, -Cw, -DRB1 and -DQB1 loci. Allelic mHAs typing was performed by PCR with sequence-specific primers for 14 autosomic mHAg and H-Y. Host versus Graft or Graft versus Host direction of immune responses in donor/recipient pairs was analyzed with use of the minor Histocompatibility Database of Leiden University Medical Center. OS and PFS were analyzed with Kaplan-Meier method and log-rank test. aGVHD and cGVHD were analyzed with a multivariate logistic regression including as covariates age, sex, previous lines of chemotherapy, disease, pre-transplant status, PS and mHAs mismatches; grade >=2 aGVHD and extensive cGVHD were considered events. 4. ResultsMedian follow-up was 34 months (2-83). One-year OS was 85%, 2- and 3-years OS were 82% and 77%. One-year PFS was 61%, 2- and 3-years PFS were 49% and 41%.The univariate analysis which considered transplant characteristics showed that OS and PFS were significantly affected by disease status at transplant (p<0.001 for both OS and PFS) and PS (<=80 vs >80, p<0.001 for both OS and PFS). Donor-vs-recipient (DR) mHAs mismatches did not significantly impact OS and PFS. The multivariate analysis which considered aGVHD as the outcome of interest, showed that the presence of at least one DR mHAg mismatch, and the presence of DR hematopoietic-restricted mHA mismatches significantly increased aGVHD incidence (p=0.02 for both). On the other hand, broad DR mHA and H-Y disparities did not affect aGVHD. DR disparities at the LB-ADIR, HA-1, HA-2 and HA-8 mHAgs did not increase the incidence of aGVHD. Recipient-vs-donor (RD) mHAg mismatches did not significantly affect aGVHD as none of the other factors considered in the multivariate associated with increased risk of cGVHD of any grade. 5. ConclusionsThis study showed that in the non-myeloablative and RIC setting, mHAg mismatches may have a significant role in determining aGVHD. Assessing mHAg mismatches may be a useful tool to choose patient-specific GVHD prophylaxis in conditioning regimens and in post transplant follow-up. Larger prospective data are needed in order to confirm these results. Disclosures:No relevant conflicts of interest to declare.

HLA-DRB1*11: a Strong Risk Factor for Acquired Severe ADAMTS13 Deficiency-Related Idiopathic Thrombotic Thrombocytopenic Purpura in Caucasians.

Abstract 2412Poster Board II-387Acquired idiopathic thrombotic thrombocytopenic purpura (TTP) is a rare form of thrombotic microangiopathy (TMA) resulting from excessive von Willebrand factor (VWF)-mediated platelet clumping and capillary occlusion in relation with an autoantibody-mediated defect in the VWF-cleaving protease ADAMTS13. So far, the mechanisms leading to the loss of tolerance of the immune system against ADAMTS13 remain unknown. The usually switched isotype of the secreted anti-ADAMTS13 antibodies implies a cooperation between T lymphocytes and B lymphocytes and thus a recognition by T cell receptors of ADAMTS13 epitopes bound to human leukocyte antigen (HLA) molecules. We therefore hypothesized that particular HLA alleles may be involved in the process leading to a loss of tolerance of the immune system against ADAMTS13. Particularly, alleles within class I A and B loci and class II DRB1 and DQB1 loci are those most frequently associated with susceptibility to autoimmune diseases.We have compared medium resolution typing of HLA class I (HLA-A, B) and II (HLA-DRB1, DQB1) loci in 61 Caucasian patients with idiopathic TTP and a documented severe (<5%) acquired, autoantibody-mediated, ADAMTS13 deficiency to 132 healthy Caucasian volunteer donors Caucasian individuals and to 42 Caucasian patients with atypical hemolytic uremic syndrome (HUS) who displayed a detectable ADAMTS13 activity.The frequency of HLA-A, -B and -DQB1 alleles was comparable between patients with acquired idiopathic TTP, healthy individuals and patients with other forms of TMA. By contrast, the HLA DRB1*11 allele was observed in 62% of patients with acquired idiopathic TTP, whereas the usually reported incidence of this allele ranges from 13.5% to 24.5%, with the lower incidence in Asian/Pacific Islanders and Caucasians and the greater incidence in Afro-Caribbeans (http://www.allelefrequencies.net). Comparison to our group of healthy individuals confirmed this striking difference, which was statistically significant (20%, P = 10-7, odd ratio [OR] = 6.43, CI95% =2.3-12.7). The increased incidence of DRB1*11 in acquired idiopathic TTP was also significant when compared to patients with a diagnosis of atypical HUS (17%, P= 6×10-5). By contrast, DRB1*11 frequency in this latter group was comparable to this observed in healthy individuals (P = n.s). All patients were heterozygous for this allele. We also observed a decreased incidence of the DRB1*04 allele in acquired idiopathic TTP when compared to healthy individuals (10% versus 30%, respectively, Pcorr = 0.025). DRB1*04, resulting in the DR53 antigen when associated with DRB4, could thus be involved as a protective allele in acquired idiopathic TTP, as suggested in a previous work. We found no association between DRB1*11 and clinical features of autoimmunity, central nervous system involvement, antinuclear antibodies, anti-ADAMTS13 inhibitors, flare-up and relapse episodes and survival. Of note, the association between DRB1*11 with acquired idiopathic TTP was not observed in Afro-Caribbeans (3/12, 25%, p=0.04). High resolution typing of DRB1*11 allele revealed that both DRB1*1101 and DRB1*1104 alleles were significantly over-represented, suggesting that the generic DRB1*11 (and not the DRB1*11 alleles) is the predisposing factor.The DRB1*11 was reported to be a risk factor for systemic sclerosis, early-onset juvenile chronic arthritis and sarcoidosis, and protective against multiple sclerosis and pemphigus vulgaris. Accordingly, we found no patient with one of those 2 latter diseases in our French National TTP registry, whereas a past history of systemic sclerosis, sarcoidosis and juvenile chronic arthritis was observed in 1 case each.Our findings propose DRB1*11 as a strong risk factor for acquired idiopathic TTP in Caucasians. Indeed, the autoimmune response in acquired idiopathic TTP may involve the recognition by T cells of a class II region of DRB1*11, bound to a peptide fragment of ADAMTS13. We also suggest that acquired idiopathic TTP represents a subset of TMA with specific genetic risk factors, distinguishing it from the other forms of idiopathic TMA. The incomplete rate of concordance may be explained by other yet unexplored mechanisms, including additional predisposing genes and environmental triggers. Forthcoming genomewide association studies should lead to the identification of additional alleles associated with the risk of acquired idiopathic TTP. Disclosures:No relevant conflicts of interest to declare.

The Effect of High-Resolution Donor-Recipient HLA Matching and Mismatching Frequencies On Choosing Donor in Chinese Population for Unrelated Allo-HSCT.

Abstract 4503The relative importance of various human leukocyte antigen (HLA) loci and the resolution level at which they are matched has not been fully defined for unrelated donor (URDs) transplantation. Hematopoietic stem cell transplantation (HCT) from volunteer URDs may give a chance of cure for patients with malignant hematological diseases. Although donor-recipient HLA matching is associated with better outcomes, many are not able to identify an HLA-A, -B, -C, -DRB1, DQB1 matched URD and are faced with choosing the closest matching among the available donors. The Chinese Marrow Donor Program (CMDP) has completed a retrospective high-resolution HLA typing on sufficient patient-donor pairs to analyze high resolution matching and mismatches probability at specific loci. These data are critical for selecting the best available partially HLA-matched donor for patients undergoing HLA-mismatched URD HCT. We have performed high-resolution typing for HLA-A,-B,-C,-DRB1,-DQB1 by using SBT, SSOP and SSP techniques on 1092 donors and 931 patients from the data base of CMDP. Among 1092 donors, the allele with highest frequency were HLA-A*1101, A*0201, A*2402, A*0207, A*3303, A*0206 and A*3001; HLA-B*4001, B*4601, B*5801, B*1302, B*1501, B*5101and B*1301; HLA-Cw*0102, Cw*0702, Cw*0304, Cw*0801, Cw*0602, Cw*0303, Cw*0302 and Cw*0401; HLA-DRB1*0901, DRB1*1501, DRB1*1202, DRB1*0701, DRB1*0803, DRB1*0405, DRB1*0301 and DRB1*1101; HLA-DQB1*0301, DQB1*0303, DQB1*0601, DQB1*0202, DQB1*0602, DQB1*0302, DQB1*0401, DQB1*0201 and DQB1*0502. The probability of HLA high-resolution DNA matching between 1092 donors and 931 patients(10/10 match) was 16.7%. Mismatching at a single HLA-A, -B, -C, -DRB1 or DQB1 locus (9/10) was 17.7%. A single mismatch at each locus of HLA-A, -Cw,- DRB1,- DQB1,- B was 6.8%, 6.3%, 2.0%, 1.7%, and 0.8%, respectively. Double mismatch (8/10) was 18.4%, such as loci A+ Cw(5.0%), DRB1+DQB1(4.6%) and B+ Cw(3.8%). The donor/patient pairs mismatched between allele of A*0201 and A*0206, A*0201 and A*0207, A*1101 and A*1102, B*4006 and B*4002, B*1501 and B*1527, Cw*0304 and Cw*0302, Cw*0304 and Cw*0303, DRB1*1501 and DRB1*1502, DRB1*1202 and DRB1*1201, DRB1*0406 and DRB1*0403, DRB1*1401 and DRB1*1454, DQB1*0303 and DQB1*0302, respectively, were statistically associated with lower-risk Allo-HSCT. These results suggested that high-resolution DNA matching or mismatching for HLA-A, -B, -C, -DRB1 and DQB1 alleles could be associated with better clinical outcome and higher survival. Furthermore, the identification of high risk mismatch and permissive mismatch would be beneficial for the selection of a suitable donor. Disclosures:No relevant conflicts of interest to declare.

Molecular variation at the HLA‐A, B, C, DRB1, DQA1, and DQB1 loci in full heritage American Indians in Arizona: private haplotypes and their evolution

A sample of 492 full heritage, unrelated residents of the Gila River Indian Community (GRIC) of Arizona were characterized for their high-resolution DNA alleles at the HLA-A, B, C, DRB1, DQA1, and DQB1 loci. Only five allelic categories are found at HLA-A, 10 at HLA-B, 8 at HLA-C and HLA-DR, and 4 at DQA1 and DQB1. There is little evidence for population structure at the 6 loci. Two 'private' alleles, B*5102 and B*4005, which are found nearly exclusively in American Indian populations in the desert southwest and northern Mexico, are likely new mutations after the first inhabitation of the area, the evolution of which are reflected in the contemporary distribution of their respective haplotypes. DRB1*1402 has the highest reported frequency of any specificity at the DRB1 locus, 0.7461, and serves as a sensitive probe for locating related east Asian populations. The haplotypes in this population also exhibit a highly restricted distribution and strong genetic disequilibria, which has important implications for matching solid organ and bone marrow allografts. It is shown that, when one considers HLA-A-B-DRB1 homozygotes as allograft donors for all full heritage members of the GRIC, 50% of the community would find a non-mismatched organ within the homozygotes for the six most common haplotypes. This raises questions about transplantation policy and whether, in the presence of high-frequency private alleles and a restricted number of haplotypes, the full heritage American Indian community of the desert southwest should act as its own pool of donors for its affected members.