Report from the killer immunoglobulin-like receptor (KIR) anthropology component of the 15th International Histocompatibility Workshop: worldwide variation in the KIR loci and further evidence for the co-evolution of KIR and HLA.

The killer immunoglobulin-like receptor (KIR) anthropology component of the 15th International Histocompatibility Workshop (IHIWS) sought to explore worldwide population variation in the KIR loci, and to examine the relationship between KIR genes and their human leukocyte antigen (HLA) ligands. Fifteen laboratories submitted KIR genotype and HLA ligand data in 27 populations from six broad ethnic groups. Data were analyzed for correlations between the frequencies of KIR and their known HLA ligands. In addition, allelic typing was performed for KIR2DL2 and 3DL1 in a subset of populations. Strong and significant correlations were observed between KIR2DL2, 2DL3 genotype frequencies and the frequency of their ligand, HLA-C1. In contrast, only weak associations were seen for 3DL1, 3DS1 and the HLA-Bw4 ligand. Although some aspects of the correlations observed here differ from those reported in other populations, these data provide additional evidence of linked evolutionary histories for some KIR and HLA loci. Investigation of allele-level variation for the B haplotype locus KIR 2DL2 showed that two alleles, *001 and *003, predominate in all populations in this study. Much more allelic variation was observed for the A haplotype locus 3DL1, with several alleles observed at moderate frequencies and extensive variation observed between populations.

A model of phenotypic susceptibility to tuberculosis: deficient in silico selection of Mycobacterium tuberculosis epitopes by HLA alleles.

HLA-DR allelic variants have been associated with tuberculosis (TB) susceptibility in different populations with risk ratios of 3.7 to 7.2. We hypothesized that the genetic susceptibility to TB depends upon the reduced capability of HLA-class II alleles of TB patients to bind and select peptide antigen from the Mycobacterium tuberculosis (MTB) expressed genome. To test this hypothesis, we developed a software that can predict HLA-DR restricted epitopes within the whole MTB genome based on quantitative peptide binding matrices. We analyzed the number of MTB epitopes recognized in two previously described populations of TB patients and matched controls and in a control population comprised of individuals affected by a sarcoid-like granuloma induced by beryllium and by healthy exposed controls. The number of putative epitopes within the whole MTB genome which could be bound by any HLA-DR allele (HLA-DR immunome of MTB) was 405,422 out of 1,304,277 possible 9-mers i.e., 31.08% of the global capability, instead of the expected 35%. When tested at an affinity level equivalent of the 1% of the best binder peptides, the HLA-DR alleles (HLA-DRB1*0801, *0802, *1401, *1501 and *1502) associated with TB susceptibility recognized a significantly lower mean number of MTB-epitopes (7,862 +/- 4,258) than the MTB-epitopes recognized by HLA-DR alleles (HLA-DRB1*0301, *0701, *1101, *1102, *1301 and *1302) negatively associated with TB (11,376 +/- 1,984, p<0.032). The number of epitopes bound at high affinity out of the whole MTB genome by the combination of the two HLA-DR alleles carried by each individual was lower in TB patients [TB-population 1: 11,341 +/- 908 (mean+SEM); TB-population 2: 15,303 +/- 657] than in matched healthy controls (CTR-population 1: 13,587 +/- 605, p<0.03 vs TB-population 1; CTR-population 2: 1,6841 +/- 555, p<0.04 vs TB-population 2). No difference was seen in individuals with the sarcoid-like granuloma induced by beryllium compared to the exposed healthy (beryllium-hypersensitivity: 17,593 +/- 447; controls 18,014 +/- 421; p=0.57). The data suggest that HLA-DR alleles associated with susceptibility to tuberculosis may be endowed with a reduced capability to bind at high affinity T-cell epitopes and select them for antigen presentation. The same alleles may contribute to determine the reaction to mycobacteria in non tuberculous granulomatous disorders.

The effect of peak and current serum panel-reactive antibody on graft survival.

BACKGROUND: Preformed antibodies against HLA antigens are known risk factors for early graft loss. Pretransplantation panel-reactive antibody (PRA) is often used to estimate the degree of sensitization. This study was conducted to determine the risk of early graft loss among subjects with a PRA cutoff value of 10%. OBJECTIVES: To evaluate the influence on 1-year graft survival of pretransplant recipient sensitization using 10% peak and current PRA cutoff values. METHODS: From January 1988 to July 2007, T-cell and B-cell PRA data were available for 247 (41%) and 241 (40%) patients, respectively. Medical records were reviewed for graft survival, current PRA value, and peak PRA value (both T and B cell). Complement-dependent cytotoxicity (CDC) is the only method of PRA identification in this study. We analyzed the correlation between PRA level and graft survival. RESULTS: Current T-cell PRA > 10% was significantly associated with poorer 1-year graft survival when compared with those with PRA < or = 10% in kidney transplantation from both donor sources: 48.6% versus 86.3% (P = .007) for living donor 94.7% versus 70.0% (P = .029) for deceased donor. Most of the graft losses in recipients with a high PRA occurred within the first 3 months posttransplantation. CONCLUSION: In our experience, current serum T-cell CDC PRA value > 10% was significantly associated with a decreased 1-year graft survival; interventions will be required to preserved graft function in these high-risk individuals.

Effect of posttransplant anti-HLA antibody on outcome of renal transplantation.

Pretransplant anti-HLA antibody has an impact on renal transplantation (RT) outcome. However, the role of posttransplant anti-HLA antibody in renal allograft outcome remains unclear. We conducted this study to determine whether posttransplant anti-HLA plays an important role in the outcome of renal allografts. Our investigation used a cross sectional design. Class I and II anti-HLA antibodies were obtained in 41 renal transplant patients. Patients had undergone either living-related (n = 15) or cadaveric (n = 26) RT. All patients had been transplanted for >6 months. The correlation of posttransplant class I and class II, anti-HLA antibodies with renal allograft function glomerular filtration rate (GFR) was analyzed. Patients displaying a GFR of >60 mL/min showed positive anti-HLA antibody status for class I (n = 2) and class II (n = 9). In contrast, those whose renal transplants showed a GFR <60 mL/min included three patients positive for HLA class I and 19 patients for HLA class II. Posttransplant class II anti-HLA antibody showed a negative correlation with GFR (r = -0.31, P = .03). Preliminary results indicated that class II posttransplant anti-HLA antibody might be one mechanism of chronic renal allograft rejection and may confirm the important role of HLA matching in renal transplantation outcome.

Associations of HLA class II alleles with pulmonary tuberculosis in Thais.

Tuberculosis is an important infectious disease in Thailand. Susceptibility to tuberculosis is influenced not only by the environment but also by host genetic factors. In this study, we investigated HLA alleles in 82 patients with tuberculosis from Bangkok and in 160 normal controls. HLA-DRB1, DQA1 and DQB1 genotyping was performed by the PCR-SSO method. The frequency of HLA-DQB1*0502 was increased in tuberculosis patients compared to the normal controls (P = 0.01, OR = 2.06). In contrast, the frequencies of DQA1*0601 and DQB1*0301 were decreased in tuberculosis patients compared to the controls (P = 0.02 and P = 0.01, respectively). Our results suggest that HLA-DQB1*0502 may be involved in the development of pulmonary tuberculosis, whereas HLA-DQA1*0601 and DQB1*0301 may be associated with protection against tuberculosis.

Analysis of TAP and HLA-DM polymorphism in thai rheumatoid arthritis.

Rheumatoid arthritis is an autoimmune disease with a strong association with DR4 in many populations. In the Thai population, rheumatoid arthritis is associated with DRB1*0405. To evaluate the role of polymorphism in TAP and HLA-DM genes, which are important in antigen processing and presentation in predisposition to rheumatoid arthritis, 82 Thai patients with rheumatoid arthritis and 100 unrelated normal controls were studied. TAP and HLA-DM typing was performed by ARMS-PCR and PCR-SSO method, respectively. There was no difference in the distribution of TAP1, TAP2, DMA, and DMB genes between the patients and controls. This study suggested that TAP and HLA-DM genes do not confer susceptibility to rheumatoid arthritis.

HLA association with hepatitis C virus infection.

Hepatitis is one of the most important infectious diseases in Thailand. The knowledge of host factors that influence the course of the disease is still limited. In this study, the HLA class I and class II phenotypes were analyzed in the 2 groups of HCV-infected Thai populations. The first group included 43 individuals with transient HCV infection (HCV antibody positive, HCV RNA PCR negative), and the second included 57 individuals with persistent chronic HCV infection (HCV antibody positive, PCR positive). HLA class I typing was performed by 2-stage microlymphocytotoxicity test, and HLA class II typing, by PCR-SSO. No significant difference in the frequencies of HLA-A and -B antigens was observed between the 2 groups of HCV-infected individuals. The frequency of DRB1*0301 and DQB1*0201 was significantly higher in the persistent-infection group than in the transient-infection group (Pc = 0.03, Pc = 0.04, respectively). In addition, DRB1*0701 and DQA1*0201 were significantly decreased in all the HCV-infected patients compared with levels in the normal controls (Pc = 0.003, Pc = 0.001, respectively). This study demonstrated that DRB1*0301 and DQB1*0201 are associated with persistent HCV infection, whereas DRB1*0701 and DQA*0201 are associated with protection against HCV infection.

Serological and molecular analysis of HLA class I and II alleles in Thai patients with psoriasis vulgaris.

The HLA class I and class II alleles in 67 patients with type I psoriasis vulgaris, 23 patients with type II psoriasis vulgaris and 140 healthy individuals were analyzed. The frequencies of HLA-A2, -B46, -B57 and DQB1*0303 were significantly increased in type I psoriasis compared to the controls (Pc<0.05). Molecular analysis of HLA-A2 alleles showed an increase in HLA-A*0207 and a decrease in HLA-A*0203 in type I psoriasis. HLA-DQB1*0301 was significantly decreased in type I psoriasis compared to the normal controls (Pc<0.05). No association of any alleles with type II psoriasis was observed. This data demonstrated two susceptible haplotypes: HLA-A1-B57-DRB1*0701-DQA1*0201-DQB1*0303 (AH57.1) and HLA-A2-B46-DRB1*0901-DQA1*0301-DQB1*0303 (AH46.1) for type I psoriasis in the Thai population. Besides, the haplotype AH46.1 was also associated with type II psoriasis.

HLA-DR and -DQ associations with melioidosis.

Melioidosis is an important infectious disease of southeast Asia caused by an intracellular bacterium, Burkholderia pseudomallei. Cellular immunity is postulated to play important roles in immunity to melioidosis that may influence the severity and clinical outcome of the disease. The present study was undertaken to investigate possible associations of melioidosis with HLA class II alleles. HLA typing of HLA-DRB1, -DQA1, and -DQB1 was performed using polymerase chain reaction and sequence-specific oligonucleotide hybridization (PCR-SSO). Seventy-nine melioidosis patients and 105 healthy, ethnically and geographically matched controls were studied. Among 24 DRB1 alleles, 7 DQA1 alleles, and 13 DQB1 alleles identified in this population, an association with melioidosis was observed with DRB1*1602 which was increased in melioidosis patients (10.1%) compared to normal controls (4.8%), p = 0.047 (odds ratio (OR) = 2.25). In addition, significant increase of DRB1*1602 allele frequency and decrease of DQA1*03 were also observed in septicemic melioidosis patients, the most severe form of the disease (p = 0.01, OR = 3.10; and p = 0.047, respectively). Furthermore, a trend of association of DRB1*0701, DQA1*0201, and DQB1*0201 with relapse cases of melioidosis was also noted. In contrast, no HLA association was observed in localized melioidosis or melioidosis with diabetes mellitus. These findings provide the suggestive evidence of an immunogenetic basis of certain aspects of melioidosis.

HLA class I typing by one-dimensional isoelectric focusing and identification of the new variants in Thai population.

One-dimensional isoelectric focusing (1D-IEF) is the technique to define HLA class I antigens based on difference in isoelectric point of HLA molecules. Different IEF subtypes are shown in different populations. In this study, 1D-IEF was employed to study HLA-A and -B subtypes in Thai population. A panel of 117 samples including all serologically defined HLA-A and -B antigens in Thai population were typed by 1D-IEF. Serological specificities and subtypes correlated well with IEF results and some antigens with unclear serological specificities could be confirmed by IEF. In addition, more subtypes could be obtained by IEF than by serology. A total of 17 IEF subtypes from HLA-A and 31 IEF subtypes from HLA-B could be identified. The subtypes predominantly found in Thai population were A2.3, A24.2, A11.1, A33.2, B15.2, B7.1 and B13.1. In addition, new IEF variants were identified in HLA-B35, B5, B56 and B48. The band positions of these variants were different from those previously described. These IEF subtypes are HLA gene products which may be important in transplantation. The combination of IEF and serology for HLA typing can provide a better definition of each allelic product of HLA-A and -B.

Analysis of TAP2 and HLA-DP gene polymorphism in psoriasis.

TAP2 is a gene, located between HLA-DP and HLA-DQ, whose products form a transporter molecule involved in endogenous antigen processing. Polymorphic residues have been described in this gene. TAP2 is of particular interest because its involvement in antigen presentation makes it a candidate for a disease susceptibility gene. In psoriasis, two clinical subtypes analogous to the situation in diabetes type I with early onset and family history and type II with later onset and without family history have been described. We have previously shown that type I but not type II psoriasis is associated with the HLA-DRB1*0701/2, -DQA1*0201, -DQB1*0303 haplotype. To investigate whether this haplotype extends to include particular TAP2 and/or DP alleles, we tested the TAP2 and HLA-DP alleles of a control group (n = 199), patients with psoriasis type I (n = 66), and patients with psoriasis type II (n = 35) by hybridization with SSOs. Our data show that there is no significant correlation between TAP2 and/or HLA-DP gene polymorphism and psoriasis type I and/or type II. We conclude that disease association in type I psoriasis is associated with the extended haplotype HLA-B57, -Cw6, -DRB1*0701/2, -DQA1*0201, -DQB1*0303.