Polymorphisms of killer immunoglobulin-like receptors (KIRs) and HLA ligands in northeastern Thais.

Killer cell immunoglobulin-like receptors (KIRs) are cell surface receptors on natural killer (NK) cells and subsets of T cells. The functions of NK cells are partly regulated by interactions between KIRs and HLA ligands on target cells. In this study, the presence or absence of 17 KIR genes and their known HLA ligands have been investigated in 235 unrelated individuals living in northeastern Thailand (NET). Subtypes of KIR2DS4 including full length (KIR2DS4F) and deleted forms (KIR2DS4D) have also been determined. Framework genes (KIR2DL4, 3DL2, 3DL3, and 3DP1) were found in all individuals and KIR genes belonging to the A haplotype (KIR2DL1, 2DL3, 3DL1, and 2DS4) were present in more than 90% of NET. KIR2DS4D (61.7%) was more common than KIR2DS4F (52.8%). A total of 33 different KIR genotypes were observed. Of these, three new genotypes were identified. The most common genotype (AA) was observed in 35.7% of NET, and HLA-C alleles bearing the C1 epitope (HLA-C1) had the highest frequency (97%). All individuals had at least one inhibitory KIR and its corresponding HLA ligand; 40.9% of NET had three pairs of receptor-ligand combinations, and 18.3% had all three receptor-ligand combinations of KIR2DL3+C1, 3DL1+Bw4, and 3DL2+A11. Surprisingly, the patterns of KIR gene frequencies in NET are more similar to those of Caucasians than Japanese, Korean, and Chinese. This is the first report on complete analysis of KIR and known HLA ligands in Thais. These data provide basic knowledge on KIR for further studies on disease associations and transplantation in northeastern Thais.

Preparation of single donor platelet with low antibody titers for all patients.

Platelet concentrates from ABO-identical donors are the components of choice for patients. However, since inventories are generally insufficient and because there is usually a relative abundance of group O donors, perfect matches are not always possible. It is therefore the accepted practice for platelets to be transfused out of the ABO group when ABO-identical platelets are unavailable. Notwithstanding, the transfusion of platelets containing high titers of antibodies to the antigens on the red blood cells of the patient can cause clinically significant hemolysis. The way to improve the safety of group O platelets has focused on defining a safe level of antibodies or reducing the volume of incompatible plasma. In the current study, 107 group O single donor platelets (SDP) were modified after collecting the platelet pellet in a bag. The AB plasma was added instead of the donor's own plasma. The direct agglutination titers of anti-A/anti-B in the original group O SDPs' plasma were performed by doing a gel test, resulting in from 1:4 to 1:1024. The prevalence of high titers (i.e., at least 1:64 in our study) was relatively high, ∼63% for anti-A and 78% for anti-B. The titer of residual anti-A/anti-B in the modified SDPs ranged from negative to 1:8. In most of the modified SDPs anti-A/anti-B could not be detected in the plasma (58.9% and 52.3%, respectively). The results indicate that our modified SDPs have very low titers; that is, acting as a universal SDP which is safe for all ABO patients. This modified SDP form is a more convenient way to overcome the risk from incompatible plasma or loss of platelets during the process of volume reduction and can help effectively manage our inventory.

Bystander T cells in human immune responses to dengue antigens.

BACKGROUND: Previous studies of T cell activation in dengue infection have focused on restriction of specific T cell receptors (TCRs) and classical MHC molecules. However, bystander T cell activation, which is TCR independent, occurs via cytokines in other viral infections, both in vitro and in vivo, and enables T cells to bypass certain control checkpoints. Moreover, clinical and pathological evidence has pointed to cytokines as the mediators of dengue disease severity. Therefore, we investigated bystander T cell induction by dengue viral antigen. RESULTS: Whole blood samples from 55 Thai schoolchildren aged 13-14 years were assayed for in vitro interferon-gamma (IFN-γ) induction in response to inactivated dengue serotype 2 antigen (Den2). The contribution of TCR-dependent and independent pathways was tested by treatment with cyclosporin A (CsA), which inhibits TCR-dependent activation of T cells. ELISA results revealed that approximately 72% of IFN-γ production occurred via the TCR-dependent pathway. The major IFN-γ sources were natural killer (NK) (mean ± SE = 55.2 ± 3.3), CD4+T (24.5 ± 3.3) and CD8+T cells (17.9 ± 1.5), respectively, as demonstrated by four-color flow cytometry. Interestingly, in addition to these cells, we found CsA-resistant IFN-γ producing T cells (CD4+T = 26.9 ± 3.6% and CD8+T = 20.3 ± 2.1%) implying the existence of activated bystander T cells in response to dengue antigen in vitro. These bystander CD4+ and CD8+T cells had similar kinetics to NK cells, appeared after 12 h and were inhibited by anti-IL-12 neutralization indicating cytokine involvement. CONCLUSIONS: This study described immune cell profiles and highlighted bystander T cell activation in response to dengue viral antigens of healthy people in an endemic area. Further studies on bystander T cell activation in dengue viral infection may reveal the immune mechanisms that protect or enhance pathogenesis of secondary dengue infection.

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 alpha1 and alpha2 domains but lack the alpha3 domain and do not associate with beta2-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.

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. MATERIALS AND METHODS: We analyzed the allelic frequencies of HLA class I and II by using the polymerase chain reaction-amplification refractory mutation system (PCR-ARMS) technique and polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP), respectively, in 140 north-eastern Thais with psoriasis that were sudivided into two groups: one with age at onset < 40 years (type I psoriasis; 95 cases) and the other with age at onset > 40 years (type II psoriasis; 45 cases). Three hundred healthy unrelated north-eastern Thais were used as controls. RESULTS: HLA-A*01, -A*0207, -A*30, -B*08, -B*13, -B*4601, -B*57, -Cw*01, -Cw*0602, and -DRB1*07 were positively associated with type I psoriasis, whereas HLA-A*24, -A*33, and -Cw*04 were negatively associated with type I psoriasis with statistical significance when compared to the controls. The Cw*0602 allele showed the strongest correlation with this type. In addition, the frequencies of HLA-A*0207, -A*30, -Cw*01, and -DRB1*1401 were significantly increased in type II psoriasis. HLA-A*207, -B*4601, -Cw*01, -DRB1*09, -DQB1*0303 (AH46.1), HLA-A*01-B*57-Cw*0602-DRB1*07-DQB1*0303 (AH57.1), and HLA-A*30, -B*13, -Cw*0602, -DRB1*07, and -DQB1*02 (AH13.1) were identified as high-risk major histocompatibility complex (MHC) halotypes for psoriasis patients in the early onset group in north-eastern Thais. CONCLUSIONS: This study demonstrates not only the differential association between HLA markers and types of psoriasis according to age at onset, but also a newly found high-risk and a protective haplotype in Thai psoriasis patients.