Differential major histocompatibility complex class I chain-related A allele associations with skin and joint manifestations of psoriatic disease

About 30% of patients with psoriasis have psoriatic arthritis (PsA), an inflammatory arthritis that can affect both axial and peripheral joints. Major histocompatibility complex class I chain-related A (MICA) alleles have previously been shown to be associated with PsA; however it is unclear whether there is a differential association of MICA alleles with skin and joint manifestations of PsA. Here, we describe a case-control study that aims to validate previously reported MICA allele associations with PsA and determine whether MICA alleles differentiate patients with PsA from those with psoriasis without PsA. Two hundred forty-nine unrelated Caucasian PsA patients, 243 psoriasis patients without arthritis, and 248 healthy controls were genotyped for 55 MICA alleles using PCR-SSP, and for human leucocyte antigen (HLA)-B and HLA-C alleles by PCR-SSO reverse line blot. Allele frequencies were calculated and logistic regressions were performed, adjusting for HLA-B and HLA-C alleles previously shown to be associated with psoriasis and/or PsA. Several MICA alleles were associated with psoriatic disease, PsA, and psoriasis compared with controls, and PsA compared with psoriasis in univariate analyses. Haplotype analysis showed evidence of strong linkage disequilibrium (LD) between PsA and psoriasis risk alleles of HLA-C, HLA-B, and MICA. After adjusting for significant HLA-B and HLA-C alleles in multivariate analyses, MICA*016 remained significantly associated with psoriasis [odds ratio (OR) = 5.5, P = 0.008]. MICA*00801 homozygosity was associated with susceptibility to PsA when compared with patients with psoriasis alone (OR = 2.26, P = 0.009). We conclude that most MICA allele associations with psoriasis and PsA are dependent on LD with HLA-B and HLA-C risk alleles. Independent of HLA, only MICA*016 influences the risk of developing psoriasis without arthritis, and homozygosity for MICA*00801 increases the risk of developing PsA in patients with psoriasis.     

Polymorphism of HLA class I genes in Meizhou Han population of Guangdong, China

Human leukocyte antigen (HLA) is an invaluable marker for anthropological studies because of its extreme polymorphism. Most of the studies carried out in Chinese populations are about HLA class II genes, but few about class I genes. In the present study, we investigated HLA class I polymorphism using polymerase chain reaction-sequencing-based typing (PCR-SBT) method in 104 unrelated Han individuals in Meizhou of Guangdong, southern China. Twenty-three HLA-A, 43 HLA-B and 27 HLA-C alleles were identified and allele frequencies and two-locus (C/B) and three-locus (A/C/B) haplotypes were statistically analysed. The most frequent HLA-A allele is A*110101 with a frequency of 30.3%, followed by A*24020101 (22.2%) and A*2420 (11.6%). Among the 43 detected HLA-B alleles, B*5801 (17.0%), B*400101 (15.5%) and B*4601 (10.0%) were frequently observed. Among the 27 detected C alleles, the most predominant one is Cw*07020101 (25.8%), followed by Cw*0717 (14.7%). The most frequent HLA-C/B two-locus haplotype is Cw*07020101/B*400101 (10.1%). The most common HLA-A/C/B three-locus haplotype in Meizhou Han is A*110101/Cw*07020101/B*400101 (3.4%). Phylogenetic tree based on HLA class I allele frequencies genetically suggested that Meizhou Han has an affinity to southern Asian populations. The result may also reflect an admixture of Han and ethnic minorities of southern China.     

HLA-C locus alleles in patients with psoriatic arthritis (PsA).

The aim of this investigation was to compare the frequency of alleles at the HLA-C locus in patients with psoriatic arthritis to that in the disease free population and to relate the HLA genes to disease phenotype in psoriatic arthritis (PsA). Ninety-four consecutive patients seen in the (PsA) clinic between April and July 1996 and 100 disease-free controls had HLA typing performed by both serologic and molecular techniques. Patients' disease was assessed according to a standard protocol. Fisher's exact test was used to compare the frequency of HLA alleles in the patients and controls. HLA-C determined by PCR-SSP decreased the frequency of non-identified, that is, "blank" (or null) alleles to 6% in patients and controls. HLA-Cw*0602 was present in 32 patients and 18 controls: allele frequency of 17% in the patients versus 9% in the controls (p < 0.01). Amongst patients with psoriatic arthritis, those who carried the HLA-Cw*0602 allele had a significantly earlier mean age of onset of their psoriasis (p = 0.003). This study confirms that molecular DNA techniques improve detection of C-locus alleles. The HLA-Cw*0602 is increased amongst patients with psoriatic arthritis compared to controls. The HLA-Cw*0602 is associated with an earlier age of onset of psoriasis.     

Novel HLA Class I Alleles Associated with Indian Leprosy Patients

Convincing results on HLA Class II associations have been reported, however data on HLA class I association are limited and inconsistent from studies in Leprosy. We present here the HLA A, B, and C allele distribution by molecular high resolution PCR-SSOP technique in 32 leprosy patients compared with the 67 controls, from the same ethnic background. The significant results from the present study were a significant increase in frequency of HLA A*0206, A*1102, B*4016, B*5110, Cw*0407, and Cw*0703 was observed when compared to controls. A striking decrease in the frequency of HLA A*0101, Cw*04011, and Cw*0602 leprosy patients was observed when compared to the controls. Further haplotype A*1102-B*4006-Cw*1502 was significantly increased among the lepromatous leprosy patients when compared to the controls. It seems that HLA class I alleles play vital roles in disease association/pathogenesis with leprosy among Indians.     

Molecular cloning and polymerase chain reaction-sequence-specific oligonucleotide detection of the allele encoding the novel allospecificity HLA-Cw6.2 (Cw*1502) in Spanish gypsies

A proposed novel allospecificity, HLA-Cw6.2, has been reported to be commonly found (25%) in Spanish Gypsies. Full-length cDNAs of the allele (Cw*1502) coding for this antigen have been cloned in this study. A simple PCR-SSO method for its detection has been standardized and a correlation with the serologic Cw6.2 phenotype has been established. This specificity has been also detected in the homozygous typing cell RMI. Although the primary structures of Cw*1502 and Cw*0601 are not closely related, they share specific motifs that may account for their serologic cross-reactivity. Two novel HLA-C alleles (Cw*12022 and Cw*0602) are also reported.     

Schizophrenia and HLA: No association with PCR-SSOP typed classical loci in a large Irish familial sample.

Susceptibility to autoimmunity is strongly influence by genes clustered in the MHC region, particularly class I and class II antigens. It has been proposed that there is an immune component in the aetiology of schizophrenia, and the distribution of human leukocyte antigens (HLA) in schizophrenic patients and controls has been investigated in numerous studies. Positive associations have been reported between schizophrenia and the HLA-A1, A2, A9, B5, Cw4, and DR8 and negative associations with HLA-DR4 and HLA-DQbeta*0602. Small sample size, variable diagnostic methodology, unreliable laboratory and statistical procedures, and possible mismatching of cases and controls may have contributed to a lack of consistency of results to date. Therefore, in this investigation we used a large and carefully diagnosed homogeneous Irish familial schizophrenic sample compared with ethnically matched controls. All alleles were determined using polymerase chain reaction amplification followed by short specific oligoprobes. We found no evidence of association with 80 HLA alleles (some previously not examined) from 4 genes. Our data therefore do not support the involvement of these classical HLA loci in the aetiology of schizophrenia at least in these Irish families. The remaining classical HLA loci (HLA-B and HLA-C) should be typed when reliable DNA-based methods become available.     

Anchored PCR cloning of the novel HLA-Cw*0704 allele detected by PCR-SSP

Abstract: The novel HLA-Cw*0704 allele, previously detected as the PCR-SSP variant Cw7/8v, has been cloned and sequenced from the homozygous typing cell KR03/4 after amplification by anchored PCR. The nucleotide sequence of Cw*0704 is closely related to those of other Cw*07 alleles, but carries specific changes in exon 3 consistent with its serological behavior - a short Cw7 cross-reactive with antibodies directed against HLA-Cw8. Some of the substitutions of Cw*0704 have not been previously described for HLA-C but are found in HLA-B alleles and in published C sequences of non-human primates. The new allele carries a novel polymorphism in its 5' untranslated region (5'ut) that could be shared by all Cw*07 alleles. By PCR-SSP, Cw*0704 is a relatively common allele in English Caucasoids at a frequency of 4.6%. It is most often observed on HLA-B44 haplotypes previously described as HLA-C "blank", although linkage disequilibria with other HLA-B specificities have been found.     

The diversity of HLA-C alleles in Japanese and their associations with HLA-B alleles

HLA-C locus alleles encoding HLA-C antigens in Japanese were identified by PCR-SSCP and nucleotide sequencing analysis. The results showed that at least sixteen alleles encode eight serologically detectable antigen groups and undetectable blanks. Cw1 was predominantly encoded by Cw^*0102, whereas two split antigens of Cw3, Cw9 and Cw10 were encoded by Cw^*0303 and Cw^*0304, respectively. Two alleles for each of Cw4 and Cw7 were identified. Cw6 in Japanese was encoded by Cw^*0602. Seven alleles belonging to four groups, Cw^*8, Cw^*12, Cw^*14 and Cw^*15, were found to encode HLA-C ‘blanks’ in Japanese. Several strong associations between HLA-C and HLA-B alleles, such as Cw^*1202-B^*5201, Cw^*1402-B^*5101 and Cw^*1403-B^*4403, were observed.     

Identification of a novel HLA-Cw*08 variant allele, Cw*0824

A novel HLA-C allele, Cw*0824, which was identified from an individual of the Han Chinese, differs from Cw*080101 at codon 222 (GAG > AAG ) in exon 4, which results in an amino acid change Glu222Lys.
In recent years, many human leukocyte antigen (HLA)-C alleles have been identified. Up to date, 23 different Cw*08 alleles have been identified according to the IMGT/HLA Database release 2.25.2 May 2009 (1) . Here, we describe the identification of the novel allele HLA-Cw*0824 that was found during routine high resolution sequence-based typing (SBT) of a Chinese stem cell voluntary donor. The HLA alleles of the donor were typed as A*11, 24; B*15, 46; and DRB1*09, 12.     

Two new HLA class I alleles recognised by PCR sequence-specific primer and sequencing based typing: B*3805 and Cw*0408

Two new HLA class I alleles have been recognised by molecular-based typing. B*3805 was initially identified by polymerase chain reaction using sequence-specific primers (PCR-SSP) and afterwards confirmed by sequencing based typing (SBT) studies in a Spanish Caucasian blood cord unit. A unique nucleotide change throughout exons 2, 3 and 4, leading to the amino acid replacement Ser11Ala, differentiates B*3801 and *3805. This position behaves as a dimorphic residue in HLA-B and -C loci, and seems to be structurally unrelated to peptide and TcR recognition. Cw*0408 was first detected by SBT in two African American bone marrow donors in combination with its most structurally related allele, Cw*04011. The single amino acid change found between Cw*04011 and Cw*0408 was Thr163Leu, a residue involved in pocket A of the peptide-binding cleft. This new allele could be the result of a gene conversion event between Cw*04011 and any of the Cw*03 alleles.     

Polymorphism in MICA rather than HLA-B/C genes is associated with psoriatic arthritis in the Jewish population

The aim of this study was to examine whether the association of psoriatic arthritis (PsA) with human leukocyte antigen (HLA) class I genes is secondary to linkage disequilibrium with a nearby gene. We examined a sample of the Jewish population to investigate whether HLA-B/C and DR polymorphism is associated with susceptibility, or whether other closely related class I loci, such as the major histocompatibility complex class I chain-related gene A (MICA) and tumor necrosis factor (TNF), might play a role in disease development. Comparisons of different populations with different HLA profiles would be of value in identifying the candidate genes involved in PSA. Fifty-two patients with PsA and 73 random matched controls from a Jewish population were selected and DNA typed by polymerase chain reaction-single-strand oligonucleotide probe (PCR-SSOP) (HLA-C), PCR sequence-specific primers (PCR-SSP) (HLA-B, -DR), radioactive PCR (MICA-TM polymorphism in the transmembrane region), and PCR-RFLP (TNF). Some findings can be concluded from the study: (1) the frequency of HLA-B*5701, B*3801, B*39, B*27, Cw*0602, Cw*07, DRB1*0402, and DRB1*0701 were not found to be significantly increased in PsA; (2) no significant differences of TNFalpha promoter alleles at positions -308 and -238 were found between PsA and healthy controls; (3) the trinucleotide repeat polymorphism MICA-A9 was present at a higher frequency in PsA patients, (p(c) < 0.009, RR = 3.34, EF = 0.39); and (4) MICA-A9 polymorphism was found in linkage disequilibrium with HLA-B alleles (B*5701, B*3801) described to be associated with PsA in Caucasians. These results suggest that the MICA gene or other nearby gene(s) may be involved in the development of PsA, and it would thus appear that psoriasis vulgaris (PsV) and PsA are associated with different MHC susceptibility genes.     

Sequencing based typing for HLA-C. Identification of three new alleles: Cw*0307, Cw*0502 and Cw*0504

HLA-C has been described as a transplantation locus in the unrelated bone marrow transplantation setting, and noticeably the number of mismatches between HLA-A,-B,-DRB1 compatible pairs is considerably high. Sequencing based typing (SBT) is an accurate and efficient methodology utilised in the HLA class I and II allele level of resolution. SBT for HLA-C locus was applied on a sample of 40 HLA-A,B,DRB1,DRB3/4/5,DQB1-compatible bone marrow recipient-donor pairs, and 3 new HLA-C alleles have been found. Cw*0307, well defined by serology as Cw3, showed two amino acid changes at the NK motif 77-80 regarding all described Cw*03 alleles, N77K80 instead of S77N80. Two new Cw*05 alleles were described, Cw*0502 properly typed by serology, and Cw*0504 that behaves as a short antigen. Cw*0502 differed from Cw*0501 by only one nucleotide at exon 3, that generated an amino acid replacement at codon 177, K to E. Cw*0504 differs from Cw*0501 by two clustered amino acid positions (114 and 116) placed at the peptide binding site. The rate of new HLA-C alleles found in this small series evidences a high grade of hidden HLA-C diversity in the Spanish population, particularly in the well-defined serologic specificities.     

Seven novel HLA alleles reflect different mechanisms involved in the evolution of HLA diversity: Description of the new alleles and review of the literature

The human leukocyte antigen (HLA) loci are among the most polymorphic genes in the human genome. The diversity of these genes is thought to be generated by different mechanisms including point mutation, gene conversion and crossing-over. During routine HLA typing, we discovered seven novel HLA alleles which were probably generated by different evolutionary mechanisms. HLA-B*41:21, HLA-DQB1*02:10 and HLA-DQA1*01:12 likely emerged from the common alleles of their groups by point mutations, all of which caused non-synonymous amino acid substitutions. In contrast, a deletion of one nucleotide leading to a frame shift with subsequent generation of a stop codon is responsible for the appearance of a null allele, HLA-A*01:123N. Whereas HLA-B*35:231 and HLA-B*53:31 were probably products of intralocus gene conversion between HLA-B alleles, HLA-C*07:294 presumably evolved by interlocus gene conversion between an HLA-C and an HLA-B allele. Our analysis of these novel alleles illustrates the different mechanisms which may have contributed to the evolution of HLA polymorphism.     

Human leukocyte antigen class I and class II allele frequencies and HIV-1 infection associations in a Chinese cohort

China has one of the most rapidly spreading HIV-1 epidemics. To develop a vaccine targeted to specific human leukocyte antigen (HLA) epitopes in this population, allele distribution analysis is needed. We performed low-resolution class I and II HLA typing of a cohort of 393 subjects from mainland China using a polymerase chain reaction with sequence-specific primers (PCR-SSPs). We found 10 class I alleles present in more than 10% of the population: HLA-A*02, HLA-A*11, HLA-A*24, HLA-B*13, HLA-B*15, HLA-B*40, HLA-Cw*03, HLA-Cw*07, HLA-Cw*01, and HLA-Cw*06. Several class II alleles were found at high frequency (>or=10%): HLA-DRB3, HLA-DRB4, HLA-DRB5, HLA-DRB1*0701, HLA-DRB1*1501, HLA-DRB1*0401, HLA-DRB1*0901, HLA-DRB1*1201, HLA-DQB1*0601, HLA-DQB1*0301, HLA-DQB1*0201, HLA-DQB1*0501, and HLA-DQB*0303. We also estimated 2- and 3-locus haplotype frequencies. Because this cohort contained 280 HIV-1-seropositive and 113 HIV-1-seronegative individuals, we compared allele and haplotype frequencies between the infected and control groups to explore correlations between HLA antigens and susceptibility/resistance to HIV infection. The HLA-B*14 allele was only found in the HIV-1-seropositive group, and many 2-locus haplotypes were significantly overrepresented in this group: HLA-B*14/Cw*08, HLA-B*51/Cw*14, HLA-A*02/B*13, HLA-A*31/Cw*14, HLA-A*02/Cw*06, and the class II haplotype HLA-DRB1*1301/DQB1*0601. Alleles significantly increased in the HIV-1-seronegative controls were HLA-B*44, HLA-Cw*04, and HLA-DRB1*1402. Overrepresented 2-locus haplotypes in the control group were HLA-B*44/Cw*04, HLA-A*31/Cw*03, HLA-A*03/Cw*07, HLA-A*11/B*13, HLA-A*11/B*38, HLA-A*24/B*52, and HLA-A*11/Cw*01. The 3-locus haplotypes HLA-A*24/Cw*03/B*40 and HLA-A*02/B*15/DRB1*1201 were found to be increased significantly in the control group. These data contribute to the database of allele frequencies and associations with HIV infection in the Chinese population.     

Schizophrenia and HLA: No association with PCR-SSOP typed classical loci in a large Irish familial sample

Susceptibility to autoimmunity is strongly influence by genes clustered in the MHC region, particularly class I and class II antigens. It has been proposed that there is an immune component in the aetiology of schizophrenia, and the distribution of human leukocyte antigens (HLA) in schizophrenic patients and controls has been investigated in numerous studies. Positive associations have been reported between schizophrenia and the HLA-A1, A2, A9, B5, Cw4, and DR8 and negative associations with HLA-DR4 and HLA-DQβ*0602. Small sample size, variable diagnostic methodology, unreliable laboratory and statistical procedures, and possible mismatching of cases and controls may have contributed to a lack of consistency of results to date. Therefore, in this investigation we used a large and carefully diagnosed homogeneous Irish familial schizophrenic sample compared with ethnically matched controls. All alleles were determined using polymerase chain reaction amplification followed by short specific oligoprobes. We found no evidence of association with 80 HLA alleles (some previously not examined) from 4 genes. Our data therefore do not support the involvement of these classical HLA loci in the aetiology of schizophrenia at least in these Irish families. The remaining classical HLA loci (HLA-B and HLA-C) should be typed when reliable DNA-based methods become available. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:422–429, 1999. © 1999 Wiley-Liss, Inc.     

Human leukocyte antigen-A, -B, and -Cw polymorphism in a Berber population from North Morocco using sequence-based typing

Class I human leukocyte antigen (HLA) polymorphism was examined in a Berber population from North Morocco, named Metalsa (ME). All data were obtained at high-resolution level, using sequence-based typing. The most frequent alleles were: HLA-A*0201 and A*0101; HLA-B*44 (B*4403 and B*4402); B*0801 and the B*50 allele group (B*5001 and B*5002); HLA-Cw*0602; and Cw*07 group (Cw*070101, Cw*070102, Cw*0702, Cw*0704, and Cw*0706), and Cw*040101. The novel HLA-B*570302 allele was identified. It differs at position 486 and position 855 from B*570301, resulting in synonymous Thr and Val. The analysis also evidenced some alleles common in Africans (A*3402, A*6802, A*7401, B*1503, B*4102, B*4202, B*7801, B*5802, Cw*1701, and Cw*1703) and some uncommon alleles (A*3004, B*2702, B*2703, B*5001,02, B*3503, and Cw*0706). The predominant HLA-A-Cw-B-DRB1-extended haplotypes in ME population were A*0101-Cw*0501-B*4402-DRB1*0402, A*240201-Cw*0701-B*0801-DRB1*030101, A*2301-Cw*040101-B*4403-DRB1*040501, A*0201-Cw*040101-B*4403-DRB1*1302, and A*3002-Cw*0602-B*5002-DRB1*0406. This study demonstrates a strong relatedness of ME to other Moroccan and North African populations, some characteristics of sub-Saharan Africans and evidenced the influence of various immigrations during centuries. Nevertheless, this study highlights some unique genetic traits of the ME population compared to other ethnic groups within Morocco, which could be of great interest for clinical aims, transplantation, and diseases.     

Molecular diversity of the HLA-C gene identified in a caucasian population

A DNA typing procedure, based on a two stage polymerase chain reaction-sequence-specific oligonucleotide probe (PCR-SSOP) typing strategy, has been developed and applied to DNA from 1000 healthy individuals from the Northern Ireland region. The two-stage procedure involves human leukocyte antigen (HLA-C) identification through the use of a medium resolution PCR-SSOP system, followed by four secondary group specific PCR-SSOP systems, to enable allele resolution. The PCR-SSOP systems were designed for the identification of HLA-Cw alleles with possible discrimination within exons 2 and 3 of the HLA-C gene, i.e., HLA-Cw*01-Cw*16. PCR-SSP tests were designed for the resolution of HLA-Cw*17 and -Cw*18 alleles. The systems can also be used independently of each other if selective allele resolution is required. HLA-Cw allele frequencies occurring within the Northern Ireland population have been compiled, along with estimations of HLA-B/Cw haplotype frequencies.     

Major histocompatibility complex class I chain-related gene A in Thai psoriasis patients: MICA association as a part of human leukocyte antigen-B-Cw haplotypes

Psoriasis is a chronic inflammatory skin disorder. Although the aetiology and pathogenesis of psoriasis are unproven, it is hypothesised that the major histocompatibility complex (MHC) gene/haplotype contributes to the susceptibility of psoriasis in many populations. MHC class I chain-related gene A (MICA), located 46-kb centromeric of HLA-B, is expressed on keratinocytes and fibroblasts. MICA is in linkage disequilibrium with HLA-B and is involved in natural killer-cell functions. To investigate the relative contribution of the MICA gene in the pathogenesis of psoriasis, extracellular polymorphisms of MICA were studied by polymerase chain reaction-sequence specific primers in 128 Thai psoriasis patients (87 and 41 were Types I and II, respectively) from Srinagarind Hospital, Faculty of Medicine, Khon Kaen University. The control group included 255 healthy, unrelated Northeast Thais. We observed 11 MICA alleles (or groups of alleles) in the patients. A comparison of the psoriasis patients and the control group revealed that MICA*010 and MICA*017 were associated with Type I psoriasis whereas only MICA*010 was associated with Type II. The haplotype analysis revealed that MICA*008-HLA-B*13-Cw*0602 and MICA*010-HLA-B*4601-Cw*01 were significantly increased in both Types I and II, whereas MICA*002-HLA-B*38-Cw*07 (01-03) and MICA*017-HLA-B*57-Cw*0602 were elevated only in Type I. MICA*010 was in strong linkage with Cw*01. Analysis of independent association of MICA*010 in individuals lacking Cw*01 failed to maintain an association. Our results suggest that a significant increase of the MICA alleles in the patient group is a part of HLA-B-Cw haplotypes. It is conceivable that an unknown susceptibility gene, on certain HLA-B-Cw haplotypes, is responsible for the development of psoriasis.     

High resolution HLA-C typing by PCR-SSP: identification of allelic frequencies and linkage disequilibria in 604 unrelated random UK Caucasoids and a comparison with serology

Recent evidence indicates that HLA-C molecules are biologically relevant by eliciting T-cell responses and exerting control over NK cell function. In addition, HLA-C is associated with susceptibility to various diseases, notably psoriasis vulgaris. Clarification of the full biological roles for HLA-C has however proved difficult because detection of HLA-C antigens by complement mediated cytotoxicity using alloantisera is inefficient. Up to 50% of individuals in every race have serologically undetectable HLA-C locus antigens due to a combination of relatively low expression, lack of serological reagents and a lack of information about the distribution of the HLA-C blank alleles. Recently, amplification of DNA using sequence-specific primers (PCR-SSP) has proved a reliable, accurate and rapid method for medium resolution HLA-C typing. We have now developed high resolution HLA-C typing by PCR-SSP utilizing allele and group-specific PCR-SSP reactions which can identify all HLA-C alleles (except non-coding change alleles) in most heterozygous combinations. Using this system we have typed 604 unrelated United Kingdom Caucasoids to generate accurate frequency and linkage disequilibrium data. To assess the validity of serology for HLA-C, PCR-SSP typings for 527 out of the 604 individuals were compared to serology. We find that the frequency of many HLA-C antigens has been underestimated by serology and some antigens such as Cw6 are consistently assigned incorrectly by serology. The overall discrepancy rate between serology and SSP was high at 37% (195/527). High-resolution HLA-C typing of 112 International Histocompatibility Workshop cell lines has also been performed.     

Identification of an HLA-B7 serological variant and its characterization by sequencing based typing

We have identified an HLA-B*07 variant allele, B*0716, in a Caucasoid cadaver kidney donor. The HLA class I type by polymerase chain reaction using sequence-specific primers (PCR-SSP) was A*01, 32; B*07, 08; Cw*07. Serological typing, using monoclonal and polyclonal anti-HLA antisera, gave disparate results for the B antigens. Monoclonal antibodies identified B7 and B8 antigens but polyclonal antisera recognised only the B8 antigen. PCR using sequencing based typing (PCR-SBT) confirmed the presence of both B*0703 and B*0801 alleles but with a mutation in one of the alleles. The HLA-B*07 allele was isolated by allele-specific PCR and was shown to have a mutation, G-->T, at 292 in exon 2. This mutation changes codon 74, which encodes aspartic acid (GAC) present in all previously identified B*07 alleles, to tyrosine (TAC) in the variant. The serological results suggest that codon 74 is a crucial part of a B7 antigen-specific epitope recognised by tissue typing polyclonal antisera.