HLA antigen and haplotype frequencies in Greeks

A random panel of 189 healthy Greek subjects was HLA typed for A, B and DR antigens. The alleles of these loci were found to be in Hardy-Weinberg equilibrium. Compared with other European Caucasoid populations, the frequencies of A9, B5, B18, B35, DR2 and DR5 were raised and that of B8 lowered. Significant linkage disequilibrium was found between a number of A/B, B/DR and A/DR antigen combinations. Some of the antigen associations usually seen in Caucasoid populations were also present in this sample (A1-B8-DR3, B14-DR1, B15-DR4) although others were missing (A3-B7-DR2, B35-DR1, B44-DR4). In addition, some antigen combinations have not been previously described. The most frequent two locus haplotypes in the Greek population are B8-DR3 and B18-DR5.     

HLA class-I and HLA class-II phenotypic, gene and haplotypic frequencies in Tunisians by using molecular typing data

The aim of this study is to define a reliable reckoning of gene frequencies and six-locus haplotypic frequencies of HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQA1, HLA-DQB1 and HLA-DPB1 in the Tunisian population. One hundred unrelated random, healthy people originating from various parts of Tunisia were typed for the alleles of the loci mentioned above by using the molecular techniques polymerase chain reaction--hybridization with oligonucleotide probe (PCR-SSO) and sequence specific primers (SSP). The population studied appeared to be in Hardy-Weinberg equilibrium. Allelic frequency distributions were observed at each locus. The most frequent HLA-A alleles were HLA-A*02 (39%) HLA-A*0101 (25%), HLA-A*30 (21%) and HLA-A*2301 (18%). Moreover, HLA-3A*3601, HLA-1A*6601, HLA-1A*3402 and HLA-2A*8001 were found; however, no HLA-A*4301 was detected. For the HLA-B locus, the most common in descending order were HLA-B*44 (22%), HLA-B*5001 (19%), HLA-B*51 (16%) and HLA-B*18 (15%). Among the 28 alleles HLA-Cw detected, HLA-Cw*6 and HLA-Cw*7 were highly predominant with the frequencies of 33 and 30%, respectively. For the HLA class-II loci, HLA-DRB1*0701, HLA-DRB1*11, HLA-DRB1*13 and HLA-DRB1*03 were the most frequent DR alleles. For the HLA-DPB1, HLA-DPB1*0401, HLA-DPB1*0301 and HLA-DPB1*0201 were the most frequent DP alleles. Many haplotypes were in a strong positive-linkage disequilibrium. The most frequent haplotypes for HLA-A, HLA-B, HLA-C and HLA-DRDQ were HLA-A*3301, HLA-B*1402, HLA-Cw*0802, HLA-DRB1*0102, HLA-DQA1*0101 and HLA-DQB1*0501; HLA-A*2402, HLA-B*0801, HLA-Cw*0702, HLA-DRB1*0301, HLA-DQA1*0501 and HLA-DQB1*0201; HLA-A*2902, HLA-B*4403.1, HLA-Cw*1601, HLA-DRB1*0701, HLA-DQA1*0201 and HLA-DQB1*0202; HLA-A*3002, HLA-B*1801, HLA-Cw*0501, HLA-DRB1*0301, HLA-DQA1*0501 and HLA-DQB1*0201, with frequencies between 0.025 and 0.015. These data can be used as control data for HLA disease associations and paternity studies, but they are also important for the evaluation of the probability rate of success in determining the optimal matched donor in unrelated stem transplantation for Tunisian patients or patients of Tunisian origin.     

Allele and haplotype frequencies at human leukocyte antigen class I and II genes in Venezuela's population

Population studies represent an integral part and link in understanding the complex chain of host-pathogen interactions, disease pathogenesis, and MHC gene polymorphisms. Genes of Mongoloid, Caucasoid, and Negroid populations have created a distinctive HLA genetic profile in the Venezuelan population. Our objective was to determine the predominant HLA class I and II alleles and haplotype frequencies in the hybrid population of Venezuela. The study population consisted of 486 healthy unrelated native Venezuelans and 180 families. We examined the frequency of HLA A-B-C, HLA-DQ and HLA-DR genes by polymerase chain reaction and subsequent hybridization with sequence-specific oligonucleotide probes. Phenotypic, allelic and haplotype frequencies were estimated by direct counting and using the maximum-likelihood method. The predominant HLA class I alleles were A*02, A*24, A*68, B*35, B*44, B*51, B*07, B*15 and Cw*07. Regarding HLA class II, the most frequent alleles were DQB1*03 and DRB1*04, DRB1*15, DRB1*13, DRB1*07. The prevailing haplotype was HLA-A*02B*35 DQB1*03 DRB1*04. Some of these alleles and haplotype frequencies were predominantly present in Amerindians (A*02, A*24, B*35, Cw*07, DRB1*04, A*24 B*35). Previous reports have shown high incidence of A*02, B*44, B*51, DRB1*15, DRB1*13, DRB1*07 alleles in several European populations and A*68, B*07, B*15 alleles in African Americans, which could have contributed to the ethnic admixture of the Venezuelan population. We conclude that our results provide strong evidence that Venezuela's population represents an admixture of the primitive Mongoloid Aborigines, Caucasoid Europeans and Western African Negroid migrants.     

HLA class II allele and haplotype frequencies in Ethiopian Amhara and Oromo populations

Abstract: HLA class II alleles were identified in 181 healthy unrelated Ethiopian children of both sexes and in 350 European controls from the South of France. The Ethiopian individuals belonged to the two major ethnic groups of the country: Oromo ( N =83) and Amhara ( N =98). In both panels, genetic polymorphism of HLA class II alleles was analysed for the first time by molecular typing of DRB1, DQA1 and DQB1 loci. Allelic and phenotypic frequencies were compared with those of European controls and other African populations. Construction of HLA class II three-locus haplo-types was also performed. The study revealed some differences between the two groups. Characteristic features of Central and North African populations appeared on the Ethiopian HLA genotypes. Surprisingly, DRB1*11 presented one of the lowest gene frequencies in both Ethiopian ethnic groups in contrast to Europeans and West Africans. Furthermore, this decrease was more marked than those observed using serological techniques in other geographically close East African countries. Oromo and Amhara only showed minor differences in spite of their different origins and histories. One significant difference consisted of a lower DRB1*01 gene frequency in Oromo as reported in most West African people. Some new or rare haplotypes were also observed in the Oromo group. Our results underline the distinctive features of the Ethiopian populations among the few HLA genotyping data available for East African groups and emphasise the major interest of such investigations in this region of Africa.     

Sequencing-based typing reveals six novel MHC class I chain-related gene B (MICB) alleles

Abstract: The MHC class I chain-related gene A (MICA) is highly polymorphic. In this paper we demonstrate polymorphism in the other expressing member of the MIC family of genes: MICB. Using a sequencing-based typing approach on cDNA, analysis of exons 2 through 6 revealed eight polymorphic sites resulting in six unique MICB sequences. Although MICB has high nucleotide homology with MICA, its polymorphism is restricted and at different sites compared to those in MICA.     

HLA-A, -B, -DR haplotype frequencies from DNA typing data of 26,266 Chinese bone marrow donors

HLA phenotypes of 26,266 Chinese individuals who were recruited as potential hematopoietic stem cell donors by the Shanghai Red Cross Marrow Donor Registry, part of the China Marrow Donor Program, were determined for HLA-A, -B, and -DRB1 alleles at low to intermediate resolution using DNA-based typing methods. The large sample size of the study allowed accurate calculation of the Chinese HLA haplotype frequencies. The observed alleles correspond to 19 HLA-A, 44 -B, and 13 -DR split antigens. The serologic equivalents of HLA-A36, -A80, -B78, and -DR18 alleles were not observed. A total of 2,241 distinct HLA-A, -B, -DRB1 haplotypes were identified. Three-locus haplotype frequency was estimated using the maximum likelihood method. The lowest haplotype frequency that can be reliably estimated at a 95% confidence level was 0.000057. Using this cutoff value, 1,220 haplotypes (54%) were statistically reliable and their cumulative haplotype frequency was 0.9730. The cumulative haplotype frequency of the remaining 1,021 haplotypes (46%) was 0.0270. A regression equation of p = 0.192 log N - 0.576 was derived to estimate the probability (p) of finding an HLA-A, -B, -DR split antigens-matched donor in a pool of N Chinese donors.     

Characterization of bovine MHC class II polymorphism using three typing methods: serology, RFLP and IEF.

Various methods, with different strengths and weaknesses, are currently used to define polymorphism of the bovine major histocompatibility complex (MHC) class II genes. A more complete characterization of bovine lymphocyte antigen (BoLA) haplotypes can be achieved by combining several of these methods. In this study BoLA class II polymorphism was characterized using three typing methods: serology, restriction fragment length polymorphism (RFLP), and isoelectric focusing (IEF). Twenty six Holstein-Friesian and 15 Angus cattle that carried an array of serologically defined BoLA haplotypes were selected for the study. The panel included 12 BoLA complex homozygotes. The three class II typing methods recognized polymorphism associated with the same or very tightly linked genes in the DQ-DR class II subregion. In total 25 BoLA-A locus (class I)--DQ-DR subregion (class II) haplotypes were defined. Three of the serological class II specificities, Dx1, Dx3, and Dx4, were associated with more than one RFLP defined DQ-DR haplotype. The other 4 class II specificities behaved as private specificities. One BoLA haplotype was found in both Holstein and Angus cattle. Two other BoLA haplotypes defined here have previously been described in other breeds. This suggests that these haplotypes exist in strong linkage disequilibrium.     

HLA class II allele and haplotype frequencies in Koreans based on 107 families

We have investigated the distribution of HLA class II alleles and haplotypes in 107 Korean families (207 parents and 291 children) for the HLA-DRB1, DRB3/B4/B5, DQA1, DQB1 and DPB1 loci. Numbers of alleles observed for each locus were DRB1: 25, DQA1: 14, DQB1: 15, and DPB1: 13. Only two to three alleles were observed for the DRB3 (*0101, *0202, *0301), DRB4 (*0103, * 0103102 N), and DRB5 (*0101, *0102) loci. These alleles showed strong associations with DRB1 alleles: DRB3*0101 with DRB1*1201, *1301 and *1403; DRB3*0301 with DRB1*1202 and *1302; DRB3*0202 with DRB1*0301, *1101, *1401 and *1405; DRB5*0101 and *0102 were exclusively associated with DRB1*1501 and *1502, respectively. The seven most common DRB1-DQB1 haplotypes of frequencies > 0.06 accounted for 52% of the total haplotypes. These haplotypes were exclusively related with the seven most common DRB1-DRB3/B4/B5-DQA1-DQB1 haplotypes: DRB1*1501-DRB5*0101-DQA1*0102-DQB1*0602 (0.085), DRB1*0405-DRB4*0103-DQA1*0303-DQB1*0401 (0.082), DRB1*09012-DRB4*0103-DQA1*0302-DQB1*03032 (0.082), DRB1*0101-DQA1*0101-DQB1*0501 (0.075), DRB1*0701-DRB4*0103-DQA1*0201-DQB1*0202 (0.065), DRB1*0803-DQA1*0103-DQB1*0601 (0.065), and DRB1*1302-DRB3*0301-DQA1*0102-DQB1*0604 (0.065). When these haplotypes were extended to the DPB1 locus, much diversification of haplotypes was observed and only one haplotype remained with a frequency of > 0.06: DRB1*0405-DRB4*0103-DQA1*0303-DQB1*0401-DPB1*0501 (0.062). Such diversification would have resulted from cumulated events of recombination within the HLA class II region, and the actual recombination rate observed between the HLA-DQB1 and DPB1 loci was 2.3% (10/438 informative meioses, including 2 recombinants informative by analysis of TAP genes). Comparison of the distribution of DRB1-DQB1 haplotypes with other populations revealed that Koreans are closest to Japanese people. However, Koreans share a few haplotypes with white people and Africans, which are rare in Japanese: DRB1*0701-DQB1*0202 and DRB1*1302-DQB1*0609. The results obtained in this study will provide useful information for anthropology, organ transplantation and disease association studies.     

HLA-DR phenotype and HLA-B,DR haplotype frequencies in 704 unrelated Danes

HLA-ABC and DR antigens were studied in 704 unrelated Danes (84 cadaver kidney donors, 307 healthy individuals, and 313 uremic patients), HLA-DR1, 2, 3, 4, 7, w8, and w10 were investigated in all individuals, whereas DR5, "DRw6", and w9 were only studied in parts of the material. The frequencies of DR1, 2, 3, 4, 5, and w10 were similar in the three groups, while those of "DRw6", DR7 and w8 differed significantly. The deviation of the DR7 frequency was small and probably due to change; "DRw6" is considered difficult to define, and DRw8 may have been difficult to define in the early part of the material. DR-phenotype distributions showed perfect fits to Hardy-Weinberg expectations for the three groups separately and for the combined group. When our combined DR antigen frequencies were compared with those from another Danish sample (Madsen et al, 1981), significant differences were found for "DRw6", w8 and w10. However, in general, the same HLA-B,DR phenotype combinations showed significant positive associations in the two samples, and most of the corresponding haplotype frequencies and delta values were quite similar.     

Clinical link between MHC class II haplotype and interferon-beta (IFN-beta) immunogenicity

Interferon-beta (IFN-beta) is currently the first-line therapy for the treatment of multiple sclerosis (MS). However, a significant percentage of MS patients develop anti-IFN-beta antibodies, which can reduce the efficacy of the drug. We describe an association between a common MHC class II allele (DRB1*0701), present in 23% of the patients studied, and the anti-IFN-beta antibody response. We identified IFN-beta epitopes using a peptide-binding assay with B cell lines expressing this allele. Moreover, epitope-specific activation responses obtained with peripheral blood mononuclear cells (PBMCs) from IFN-beta treated patients with the DRB1*0701 allele indicated a role for T-cell activation in IFN-beta immunogenicity. These results suggest that HLA typing of MS patients may provide an accurate screen for subjects who are likely to develop anti-IFN-beta antibodies and should therefore be considered for alternative therapies. In addition, elucidation of the factors underlying the anti-IFN-beta antibody response should accelerate the engineering of less immunogenic IFN-beta therapeutics.     

Heterogeneity of class I and class II MHC sequences in Schistosoma mansoni

We investigated the genetic variations in class I and class II major histocompatibility complex (MHC) genes of Schistosoma mansoni and the effects of host MHC genotypes. S. mansoni was maintained in combinations of two mouse strains with different MHC genotypes, and the MHC gene sequences of the cercariae were investigated. The detected class I MHC gene sequences were variable, with high similarity between the H-2D^b murine host and the parasite. For other combinations, however, the parasite sequence was homologous to those of anthropoids. All class II MHC sequences detected in S. mansoni were homologous to those of anthropoids. Our results suggest that the genetic variation in the MHC sequences of S. mansoni is derived in part from the current host, indicating horizontal transfer of the sequences from mammal to parasite.     

Expression of MHC class I and class II antigens in pancreatic adenocarcinomas

The antigens encoded by the major histocompatibility complex (MHC) are cell surface glycoproteins that play a fundamental role in the regulation of the immune response. Anomalous MHC expression in tumor cells has been viewed as an important feature to escape tumor recognition by immune cells. Low or absent MHC class I expression as well as ectopic MHC class II expression have been often observed to correlate with high grade malignancy and metastatic potential in a variety of human cancers. To date, very little investigation of MHC (HLA in man) class I and class II expression inhuman pancreatic cancer has been reported. We investigated this aspect on frozen sections of 8 pancreatic adenocarcinomas and 18 established in vitro cell lines. HLA class I was expressed in all but two cancers whereas de novo HLA class II expression was detected in 3 of 8 cancers. Interestingly, a hierarchy in the expression of the various subsets of HLA class II was found with HLA-DR>-DP>-DQ. Results on cell lines strongly resembled the ones obtained in cancer tissues. However, a peculiar feature was observed in certain cell lines. HLA class II antigens were expressed in only a few cell lines and in some of them a mixed population of positive and negative cells was found. Sorting and cloning of the two populations confirmed the existence of tumor cell clones with stable and distinct HLA class II phenotype. Taken together, these results indicate the cellular heterogeneity of pancreatic cancer cells with regard to the qualitative and quantitative expression of major histocompatibility complex genes, and may provide new insights for a better understanding of the tumor-host relationships in this extremely severe form of neoplasia.     

Expression of MHC class I and class II antigens in colonic carcinomas

Malignant and non-malignant ('normal') colonic tissues from patients with colonic carcinoma were examined for the expression of MHC class I and class II antigens by immunoenzymatic staining using monoclonal antibodies. The amount of class I antigen as detected by 2 monoclonal antibodies, FMC 16 or W6/32 was clearly diminished in 11 of 14 tumours when compared to the amount present on 'normal' colonic tissue from the same individual. The loss of class I antigen did not correlate with tumour stage or differentiation. The reactivities of FMC 16 and W6/32 with these tissues were not identical, which indicates that the 2 monoclonal antibodies may recognize different epitopes on the HLA class I molecule. Class II antigens were absent from 'normal' colonic epithelium but were present on 20 of 28 tumours, with DR being detected more often than DP, and DQ found only on 4 of 28 tumours. When present, staining for class II antigens was heterogeneous within the tumour, in that all tumour cells did not stain equally. DR and DP antigens were found more often on moderately or poorly differentiated adenocarcinomas and on stage B, C and D tumours in that order of frequency. Thus tumours with a better prognosis were less likely to express DR and DP. The expression of DQ was unrelated to staging or differentiation.