Amornrat Romphruk

HLA class I and II alleles and haplotypes in ethnic Northeast Thais

Allele frequencies (AFs) and haplotypic associations of human leukocyte antigen (HLA) class I and II were investigated in 400 unrelated, healthy, ethnic Northeast Thais. HLA-A, -B, -Cw, -DRB1 and -DQB1 were typed by polymerase chain reaction-sequence specific primer, -sequence specific oligonucleotide probe and -single-strand conformation polymorphism methods. In this population, 17 HLA-A, 26 HLA-B, 15 HLA-Cw, 26 HLA-DRB1 and 13 HLA-DQB1 alleles (or groups of alleles) were found. AFs > 10% included A*11 (23.3%), 24 (18.8%), 0207 (14.4%), 33 (11.5%), 0203 (10.6%); B*4601 (13.9%); Cw*07(01-03) (18.5%), 01 (15.9%), 04 (12.0%), 0304 (10.6%); DRB1*1502 (18.5%), 1202 (13.4%); DQB1*0502 (20.3%), 0501 (16.3%), 0301 (14.1%) and 02 (10.9%). The most common of 2-locus haplotypes included A*0207-B*4601 (9.3%), B*4601-Cw*01 (13.5%), B*5801-DRB1*0301 (5.8%) and DRB1*1502-DQB1*0501 (14.1%). Of the 49 five-locus HLA haplotypes identified, 24 were confirmed in 31 family studies: the most common being; A*33-Cw*0302-B*5801-DRB1*0301-DQB1*02 (4.6%), A*0207-Cw*01-B*4601-DRB1*09-DQB1*0303 (3.4%) and A*33-Cw*07(01-03)-B*44-DRB1*07-DQB1*02 (2.6%). Apparently, the HLA-B*46-carrying haplotype is fragmented in ethnic Northeast Thais, including seven haplotypes with different HLA-A and HLA-DR/DQ combinations. One of these haplotypes (A*11-Cw*01-B*4601-DRB1*1202-DQB1*0502) has not been reported in other Asians. The results indicated that there were marked differences in the distribution of HLA alleles and haplotypes between ethnic Northeast Thais and other ethnic groups in Southeast and East Asia. These results also dictate that future studies of HLA alleles and diseases need precise identification of ethnically and geographically matched controls. The HLA allele and haplotype analyses in this large sample provide baseline information on ethnic Northeast Thais for anthropological studies and for determining HLA allele/haplotype frequencies when searching for HLA-compatible donors for unrelated bone marrow transplantation.

Haplotype associations of the major histocompatibility complex with psoriasis in Northeastern Thais

Background  To evaluate the distributions of the human leukocyte antigen (HLA) at class I and II loci that may contribute to the genetic susceptibility to psoriasis patients in the north‐eastern Thai population.

Polymorphisms of NKG2D ligands: diverse RAET1/ULBP genes in Northeastern Thais

Unique long 16 (UL-16)-binding proteins (ULBP) or retinoic acid early transcripts-1 (RAET1) are ligands to the activating receptor, NKG2D. The human RAET1/ULBP gene family is identified as ten members (RAET1E to N) with six loci encoding for potentially functional proteins. These are ULBP1 or RAET1I, ULBP2 or RAET1H, ULBP3 or RAET1N, and RAET1L, which are glycosylinositol phospholipid (GPI)-linked glycoproteins and ULBP4 or RAET1E and ULBP5 or RAET1G, which are transmembrane glycoproteins. The RAET1 products contain the α1 and α2 domains but lack the α3 domain and do not associate with β2-microglobulin. RAET1/ULBPs have tissue-specific expressions, and some of them are also polymorphic. In the present study, polymorphic exons 2 and 3 of the RAET1E, G, H, I, L, and N were analyzed using sequence-based typing. One hundred and seventy-six unrelated healthy Northeastern Thais were included in this study. For RAET1E, RAET1G, RAET1H, and RAET1L, there were seven, two, five, and four single nucleotide polymorphisms (SNPs), respectively. Six of these are new SNPs, which are rare in this population. Of these, six new SNPs, two of two in RAET1E, two of three in RAET1H, and none of one in RAET1L are nonsynonymous substitutions. Interestingly, although the RAET1N is polymorphic in Caucasians, RAET1N and RAET1I had no variation in Thais indicating diverse RAET1 genes in different ethnic groups. These data provide the important basis for future analysis on the role of RAET1 genes in immune responses especially in cancer and infectious diseases.

Frequency of human platelet antigens among blood donors in northeastern Thailand

BACKGROUND: Platelet transfusions have been widely used in Thailand, but little is known about the phenotyping of human platelet antigens.

Azathioprine-induced fatal myelosuppression in a renal-transplant recipient who carried heterozygous TPMT*1/*3C.

Bone Marrow Transplant 1997; 20: 171. 3. Darrington DL, Vose JM, Anderson JR, et al. Incidence and characterization of secondary myelodysplastic syndrome and acute myelogenous leukemia following high-dose chemotherapy and autologous stem-cell transplantation for lymphoid malignancies. J Clin Oncol 1994; 12: 2527. 4. Pedersen-Bjergaard J, Andersen MK, Christiansen DH. Therapy-related acute myeloid leukemia and myelodysplasia after high-dose chemotherapy and autologous stem cell transplantation. Blood 2000; 95: 3273. 5. Krishnan A, Bhatia S, Slovak ML, et al. Predictors of therapy-related leukemia and myelodysplasia following autologous transplantation for lymphoma: an assessment of risk factors. Blood 2000; 95: 1588.

Alu polymorphism within the MICB gene and association with HLA-B alleles

We describe the finding of an Alu repeat dimorphism within the first intron of the MICB gene. The frequencies of the two AluyMICB alleles, AluyMICB*0 (absence of insertion) and AluyMICB*1 (presence of insertion), and their associations with the highly polymorphic HLA-B locus were determined for 51 human cell lines and for 109 and 200 Caucasians and northeastern Thais, respectively. Analysis of the AluyMICB and HLA-B allelic relationships revealed that AluyMICB*1 occurred at relatively low gene frequency (0.113–0.118) but was strongly associated with HLA-B17 (HLA-B57,HLA-B58) and HLA-B13. The AluyMICB locus provides a useful dimorphic marker for investigations on the level of linkage disequilibrium between MICB, MICA, and HLA-B loci.

Burkholderia pseudomallei Proteins Presented by Monocyte-Derived Dendritic Cells Stimulate Human Memory T Cells In Vitro

ABSTRACT Melioidosis is a severe infectious disease caused by the saprophytic facultative intracellular pathogen Burkholderia pseudomallei. The disease is endemic in Southeast Asia and Northern Australia, and no effective vaccine exists. To describe human cell-mediated immune responses to B. pseudomallei and to identify candidate antigens for vaccine development, the ability of antigen-pulsed monocyte-derived dendritic cells (moDCs) to trigger autologous T-cell responses to B. pseudomallei and its products was tested. moDCs were prepared from healthy individuals exposed or not exposed to B. pseudomallei, based on serological evidence. These were pulsed with heat-killed B. pseudomallei or purified antigens, including ABC transporters (LolC, OppA, and PotF), Bsa type III secreted proteins (BipD and BopE), tandem repeat sequence-containing proteins (Rp1 and Rp2), flagellin, and heat shock proteins (Hsp60 and Hsp70), prior to being mixed with autologous T-cell populations. After pulsing of cells with either heat-killed B. pseudomallei, LolC, or Rp2, coculturing the antigen-pulsed moDCs with T cells elicited gamma interferon production from CD4+ T cells from seropositive donors at levels greater than those for seronegative donors. These antigens also induced granzyme B (cytotoxic) responses from CD8+ T cells. Activation of antigen-specific CD4+ T cells required direct contact with moDCs and was therefore not dependent on soluble mediators. Rp peptide epitopes recognized by T cells in healthy individuals were identified. Our study provides valuable novel data on the induction of human cell-mediated immune responses to B. pseudomallei and its protein antigens that may be exploited in the rational development of vaccines to combat melioidosis.

Microsatellite alterations in liver fluke related cholangiocarcinoma are associated with poor prognosis.

We have characterized the role of genetic alterations in the development of liver fluke related cholangiocarcinoma. We analyzed the loss of heterozygosity (LOH) and microsatellite instability (MSI) of hMSH2, hMLH1, and p53 genes in 55 patients with intrahepatic cholangiocarcinoma by using polymerase chain reaction based microsatellite markers D2S119, D3S1611, and TP53, respectively and determined the association between microsatellite alterations and patient survival. A total of 27 (49.1%) out of 55 cases exhibited microsatellite alterations in one locus or more. Of 55 samples, 11 (20%) demonstrated MSI at D2S119 and four (7%) showed MSI at D3S1611. LOH was shown in seven out of 36 (19%) informative cases for D3S1611 and 16 out of 50 (32%) for TP53. Microsatellite alterations at loci studied were significantly associated with poor survival (P=0.0098). This study suggests that genetic alterations of DNA mismatch repair genes and tumor suppressor gene p53 may be involved in cholangiocarcinogenesis and these alterations may be of value as prognostic indicators for liver fluke related cholangiocarcinoma.

Associations of MICB with cervical cancer in north‐eastern Thais: identification of major histocompatibility complex class I chain‐related gene B motifs influencing natural killer cell activation

The expression of MICB, a member of the major histocompatibility complex class I chain‐related gene B family, is induced in response to cellular stress. It is one of the ligands to the NKG2D receptor. MICB is polymorphic, but the distribution of MICB polymorphism in north‐eastern Thais and their potential associations with cancer have not yet been elucidated. In this study, polymerase chain reaction–sequence‐specific primers were developed to identify 15 MICB alleles and one group of alleles. We performed MICB typing in 100 healthy north‐eastern Thai females (NETF) and 99 cervical cancer patients to evaluate the association of MICB polymorphisms and the risk of developing cervical cancer. Eight and nine alleles were detected in the NETF and cervical cancer respectively. MICB*00502 was associated negatively with a corrected P‐value of 0·0009, suggesting the existence of a protective allele in cervical cancer. Amino acid substitutions carried by this allele were investigated for their potential involvement in natural killer (NK) cell activation. Although lysine at amino acid position 80 (Lys80) and aspartic acid at position 136 (Asp136) were associated negatively with cervical cancer, only MICB carrying Asp136 could induce NK cell killing more efficiently than MICB‐Lys80 when the NK cells were blocked by anti‐NKG2D. This result suggested that aspartic acid at position 136 may affect NKG2D binding, leading to different degrees of immune cell activation.

HLA-B*27 subtypes in Northern and Northeastern Thais, Karens, and Bamars determined by a high-resolution PCR-SSP technique

Human leukocyte antigens (HLA), class I, are a group of antigens expressed on most nucleated cell surfaces. They transport endogenous peptides to the cell surface for recognition by T-cell receptors. Their functions are involved in immune responses. Many diseases are associated with HLA alleles, especially HLA-B*27 that is strongly associated with ankylosing spondylitis (AS). HLA-B*27 consists of 42 subtypes. Different subtypes of HLA-B*27 were reported in different ethnic groups of AS patients. In this study, a high-resolution polymerase chain reaction-sequence-specific primer technique has been developed to define all the HLA-B*27 subtypes with a total of 29 primer mixtures. Two of the primer mixes were used to detect the HLA-B*27-specific group, and 27 primer mixes were used to identify 42 subtypes (B*2701-B*2721 and B*2723-B*2743). The HLA-B*27-group-specific primers have been tested in unrelated healthy subjects; 846 Northeastern Thais (NET), 334 Northern Thais (NT), 264 Karens, and 310 Bamars. Sixty-three NET (phenotype frequency, PF = 7.4%), 24 NT (PF = 7.1%), 5 Karens (PF = 1.8%), and 12 Bamars (PF = 3.9%) were positive for HLA-B*27. Only B*2704 was found in Karens, whereas B*2704, B*2705/37/39, B*2706, and B*2707 were found in NET and NT. In Bamars, B*2704, B*2705/37/39, B*2706, and B*2725 were found. The distribution of HLA-B*27 subtypes was compared with other studies in Asian and Caucasian populations. Significant differences of the distribution of HLA-B*27 subtypes were found in most of the populations. This study established a simple technology for HLA-B*27 subtyping and provided basic information for anthropology and further studies in disease associations.