Kouichi Kashiwase

Sequence-based association analysis of HLA class I and II alleles in Japanese supports conservation of common haplotypes

Abstract Alleles of HLA-A, B, C, DRB1, DQB1, and DPB1 loci were fully determined in 117 healthy Japanese. A*2402, A*3303, A*1101, A*0201, B*4403, B*5201, Cw*0102, Cw*1403, Cw*0304, Cw*0702, Cw*0801, and Cw*1202 showed frequencies of over 10%. Multi-locus haplotype frequencies were estimated by the maximum likelihood method. Strength of association between C and B loci was comparable with that between DRB1 and DQB1 loci. Alleles unidentified by a serological method and having very similar nucleotide sequences (A2: A*0201, A*0206, A*0207, B61: B*4002, B*4006) were carried by different haplotypes. Several frequent five-locus haplotypes were identified including A*3303-Cw*1403-B*4403-DRB1*1302-DQB1*0604, and A*2402-Cw*1202-B*5201-DRB1*1502-DQB1*0601. These sequence-based haplotypes corresponded to serology-based common haplotypes which have already been described in Japanese. These findings indicate that common HLA haplotypes consist of particular sets of HLA alleles and that these haplotypes have been conserved through recent human evolution.

Behcet's Disease Associated With one of the HLA-B51 Subantigens, HLA-B* 5101

The strong association of Behçets disease with HLA-B51 in several ethnic groups is well known. Because the HLA-B51 antigen has been recently identified to comprise three alleles, HLA-B* 5101, HLA-B* 5102, and HLA-B* 5103, we sought to investigate whether there is any correlation of one particular allele among them with B51-positive patients with Behçets disease. Forty-six Japanese patients with Behçets disease and HLA-B51 were typed by using the alloantisera, which allowed the subdivision of B51 antigen by the microlymphocyte toxicity assay. All the patients were found to carry HLA-B* 5101. This result suggests that amino acid substitutions at residue 167 or 171 prevent the development of Behçets disease, because HLA-B* 5101 differs from HLA-B* 5102 and HLA-B* 5103 by single amino acid substitution at residues 171 and 167, respectively, or that another non-HLA gene tightly linked to the HLA-B* 5101-associated haplotype around the HLA class I gene region is responsible for the susceptibility to Bechçets disease. This study provides insight into the molecular mechanism underlying an HLA association with Behçets disease.

MIC-A polymorphism in Japanese and a MIC-A-MIC-B null haplotype.

Abstract A polymorphic gene, MIC-A, is one of the MIC family of genes which is composed of a group of homologous genes interspersed in the class III and class I regions of the major histocompatibility complex. MIC-A is located 46 kilobases (kb) centromeric of HLA-B, and is preferentially expressed in the epithelial cells and intestinal mucosa. Recently, MIC-A and the closely related MIC-B were reported as the molecules that conferred specificity in the recognition by the Vδ1γδT cells. In the present study, polymorphic exons 2, 3, and 4 of the MIC-A gene were analyzed using the polymerase chain reaction-single-strand conformation polymorphism method. The number of patterns found in exons 2, 3, and 4 were 5, 6, and 4, respectively, in 114 healthy Japanese subjects. Eight MIC-A alleles were observed in Japanese individuals, among which one, tentatively named MIC-AMW, has not previously been reported. There was a strong linkage disequilibrium between MIC-A and HLA-B loci: each MIC-A allele showed strong association with a particular HLA-B group. In contrast, B*3901 showed association with multiple MIC-A alleles. Furthermore, the existence of a MIC-A-MIC-B null haplotype, which is associated with HLA-B*4801, was identified. In this haplotype, a large-scale deletion (of approximately 100 kb) including the entire MIC-A gene was indicated and the MIC-B gene possessed a stop codon.

Splice acceptor site mutation of the transporter associated with antigen processing-1 gene in human bare lymphocyte syndrome

Expression of histocompatibility leukocyte antigen (HLA) class I molecules on the cell surface depends on the heterodimer of the transporter associated with antigen processing 1 and 2 (TAP1 and TAP2), which transport peptides cleaved by proteasome to the class I molecules. Defects in the TAP2 protein have been reported in two families with HLA class I deficiency, the so-called bare lymphocyte syndrome (BLS) type I. We have, to our knowledge, identified for the first time a splice site mutation in the TAP1 gene of another BLS patient. In addition, class I heavy chains (HCs) did not form the normal complex with tapasin in the endoplasmic reticulum (ER) of the cells of our patient.

Guillain–Barré and Fisher's syndromes subsequent to Campylobacter jejuni enteritis are associated with HLA-B54 and Cw1 independent of anti-ganglioside antibodies

The frequencies of human leukocyte antigens (HLA)-class I (A, B and Cw) were determined serologically and those of HLA-class II (DRB1 and DQB1) at the genomic level in 35 Japanese patients with Guillain-Barré syndrome (GBS), 58 with Fishers syndrome (FS), and 112 healthy controls. HLA-B54 and -Cw1 antigens were found in GBS and FS patients from whom Campylobacter jejuni had been isolated more often than found in the healthy controls. No HLA types were related to GBS or FS as a whole, except for the B54 antigen which often was significant in the entire GBS group. This relation, however, may depend on the high population of C. jejuni-isolate patients in our GBS group. There were no relationships between the frequencies of HLA types and the presence of serum IgG antibodies to GM1, GQ1b, GD1a, or GalNAc-GD1a. Our findings suggest that HLA types are associated with the onset of GBS and FS after C. jejuni enteritis and that the HLA types in distinct GBS and FS subgroups of a single etiological origin need to be examined.

Association of HLA-A*3303-B*4403-DRB1*1302 haplotype, but not of TNFA promoter and NKp30 polymorphism, with postherpetic neuralgia (PHN) in the Japanese population.

Herpes zoster is a common disease caused by reactivation of the varicella zoster virus (VZV). In a small number of herpes zoster patients, pain persists beyond 4 weeks or more after healing of vesicular eruptions; this condition is termed postherpetic neuralgia (PHN). Positive associations of human histocompatibility leukocyte antigens (HLA) class I antigens, A33 and B44, with PHN in the Japanese population have been reported. Our hypothesis is that susceptibility genes to PHN might exist in the HLA region and the study objective is to further examine possible associations of genes in HLA class I, II and III regions, HLA-A, -B, -DRB1, tumor necrosis factor α (TNFA) promoter, and a natural killer cell activating receptor, NKp30 polymorphisms with PHN. Although TNFA or NKp30 in the class III region had been considered as a candidate locus, we found no associations of TNFA promoter or NKp30 polymorphisms with PHN in this study. We demonstrated that HLA-A*3303, -B*4403 and -DRB1*1302 alleles were significantly associated with PHN (P=0.0007 for A*3303, P=0.001 for B*4403 and P=0.001 for DRB1*1302). The frequency of the HLA-A*3303-B*4403-DRB1*1302 haplotype was also significantly higher in the PHN patients than in the healthy controls (P=0.0039). Our results suggest that this haplotype might be related to the pathogenesis of PHN.

Single nucleotide polymorphisms and outcome risk in unrelated mismatched hematopoietic stem cell transplantation: an exploration study

Genetic risk factors contribute to adverse outcome of hematopoietic stem cell transplantation (HSCT). Mismatching of the HLA complex most strongly determines outcomes, whereas non-HLA genetic polymorphisms are also having an impact. Although the majority of HSCTs are mismatched, only few studies have investigated the effects of non-HLA polymorphisms in the unrelated HSCT and HLA-mismatched setting. To understand these effects, we genotyped 41 previously studied single nucleotide polymorphisms (SNPs) in 2 independent, large cohorts of HSCT donor-recipient pairs (n = 460 and 462 pairs) from a homogeneous genetic background. The study population was chosen to pragmatically represent a large clinically homogeneous group (acute leukemia), allowing all degrees of HLA matching. The TNF-1031 donor-recipient genotype mismatch association with acute GVHD grade 4 was the only consistent association identified. Analysis of a subgroup of higher HLA matching showed consistent associations of the recipient IL2-330 GT genotype with risk of chronic GVHD, and the donor CTLA4-CT60 GG genotype with protection from acute GVHD. These associations are strong candidates for prediction of risk in a clinical setting. This study shows that non-HLA gene polymorphisms are of relevance for predicting HSCT outcome, even for HLA mismatched transplants.

Molecular analysis of HLA-B39 subtypes

Serological studies have suggested the presence of a new HLA-B39 subtype (B39.2) in the Japanese population. To identify the new HLA-B39 subtype and compare it with an other HLA-B39 subtype (B39.1), the genes encoding HLA-B39.1 (B*39013) and B39.2 (B*3902) have been cloned from Japanese. We have sequenced these genes and completed the sequence of HLA-B39.1 (B*39011) gene from a Caucasian that was partially sequenced. Comparison of the sequence data revealed that B*3902 and B*39013 differ by three nucleotide substitutions which result in a two amino acids change at residues 63 and 67, while one silent substitution at codon 312 is found between B*39011 and B*39013. These results suggest that B*3902 has evolved from B*39013 rather than B*39011.

Polymorphisms of HLA genes in Western Javanese (Indonesia): close affinities to Southeast Asian populations.

Identification of human leukocyte antigen (HLA) antigens that are known as the highest polymorphic genes has become a valuable tool for tissue transplantation, platelet transfusion, disease susceptibility or resistance, and forensic and anthropological studies. In the present study, the allele and haplotype frequencies of HLA-A, HLA-B, and HLA-DRB1 were studied in 237 unrelated healthy Western Javanese (Indonesia) by the high-resolution polymerase chain reaction-Luminex method. A total of 18 A, 40 B, and 20 DRB1 alleles were identified. The most frequent HLA-A, -B, and -DRB1 alleles were HLA-A*2407 (21.6%), HLA-B*1502 (11.6%) and HLA-B*1513 (11.2%), and DRB1*1202 (37.8%), respectively. The most frequent two-locus haplotypes were HLA-A*2407-B*3505 (7%) and HLA-B*1513-DRB1*1202 (9.2%), and three-locus haplotypes were HLA-A*3401-B*1521-DRB1*150201 (4.6%), HLA-A*2407-B*3505-DRB1*1202 (4.3%), and HLA-A*330301-B*440302-DRB1*070101 (4.2%). HLA allele and haplotype frequencies in addition to phylogenetic tree and principal component analyses based on the four-digit sequence-level allele frequencies for HLA-A, HLA-B, and HLA-DRB1 showed that Western Javanese (Indonesia) was closest to Southeast Asian populations.

Structural analysis of HLA-B40 epitopes

Two genes encoding HLA-B60 or HLA-B61 were cloned from Japanese and the exons of their genes were sequenced. One silent mutation was observed at the exon 1 between HLA-B60 (B*40012) and B*40011. Seven nucleotide substitutions were seen at the exon 3 between HLA-B61 (B*4006) and B*4002. Three substitutions at codon 95, CTC in B*4002 to TGG in B*4006, changed Leu in B*4002 to Trp in B*4006, while two substitutions at codon 97, AGC in B*4002 and ACG in B*4006, changed Ser in B*4002 to Thr in B*4006. Since B*4002 shares the epitope of alloantibodies specific for HLA-B61, two HLA-B61 subtypes are discriminated by two amino acid substitutions at residues 95 and 97. B*40012 and B*4006 differ by four amino acid substitutions on the beta sheet and five amino acid substitutions on the alpha 2 helix. Since the residues at the beta sheet seem hardly to affect the binding of alloantibody, it is suspected that the residues on the alpha 2 helix provide epitopes for alloantibodies that discriminate allospecificity between HLA-B60 and HLA-B61.