HLA gene and haplotype frequencies in a Nagaybaks population from the Chelyabinsk Region (Russian South Urals)

A total of 112 Nagaybaks, a Turkic ethnoconfessional group living mainly in the Nagaybak district of the Chelyabinsk Region of Russian South Urals, were genotyped for HLA-A, -B, -DRB1, -DQA1 and -DQB1 loci using PCR-SSP (low-resolution) and HLA-A29 (high-resolution). All loci were in Hardy-Weinberg equilibrium (all p values >0.1 thus showing no locus-level deviations. The genotype data are available in the Allele Frequencies Net Database under the population name ''Russia, South Ural, Chelyabinsk Region, Nagaybaks" and the identifier AFND0003397.

Epitopes and motifs of the HLA-B*14 allele family products and related HLA-B14 cross-reactive specificities

The split specificities of HLA-B14 (B64, B65) are assigned to the B*14:01 (B64) and B*14:02 (B65) products only. Of the further 50 B*14 expressed products, only B*14:03 and B*14:06 are officially designated as HLA-B14. The B*14:08 product differs from B64 by a single amino acid substitution of W97R, while the B*14:53 specificity (which is a "short" B14 and neither B64 nor B65) differs from B64 by three residues (W97S, Y113H and F116Y). Comprehensive testing of B*14:08:01 cells (using 49 alloantisera with B64 or B64, B65 specificities, and five monoclonal antibodies with B65 or B64, B65 activity) showed that the B*14:08 specificity is, like the B*14:53 product, neither B64 nor B65 and appears as a "short" B14 specificity. To help understand the serological reactivity of the B*14:08 and B*14:53 products, and B64 and B65, we identified seven published epitopes (11AV, 97W, 61ICT, 116F, 131S+163T, 170RH and 420) and, by inspection, 29 motifs, that encompass one or more of B64, B65 and various HLA-B14 cross-reactive group specificities. We then considered the possession of these epitopes and motifs by the products of B*14:01 to B*14:06, B*14:08 and B*14:53. Seventeen of the 29 motifs fully complied with the one-/two-patch functional epitope concept for amino acid proximity, as determined by Cn3D software, the remainder partially complied. The nature and patterns of epitopes and motifs possessed by both B*14:08 and B*14:53 specificities supported their designation as HLA-B14 but non-B64/B65. Also that epitope 97W, with 11S or 11A, is critical for serological B64 and B65 reactivity. And conversely, that epitope 116F, and several identified motifs, are probably unimportant for HLA-B14 antibody reactivity. The previous submission that the B*14:03 specificity is HLA-B65 was compatible with its epitope/motif pattern. B*14:04 cells would also be expected to react as B65, based on its epitope/motif pattern, and not as B64 as previously implied. Also, from their epitope/motif patterns, and external serological information, it is probable that the B*14:05 and B*14:06 specificities will both appear as "short" HLA-B14, non-B64/B65. Several epitopes and motifs encompassed a range of HLA-B specificities included in the serological HLA-B14 cross-reactive group, thus supporting these original serological findings.

The HLA-C*05 family allele - C*05:142

The sequencing of exons 2-7 of a likely new HLA-C*05 allele identified the second example of HLA-C*05:142, in a male UK European, within a few months of the first example being found in Germany. C*05:142 differs from C*05:01:01:01 by a single base (395G>C) in exon 3 resulting in an amino acid substitution of R108P. Comprehensive serological HLA-Cw5 typing, using 19 antisera, indicated that C*05:142 encodes a "normal" Cw5 specificity. Failure to identify the involvement of position 108 in published HLA-C epitopes supported this assertion. The likely HLA class I C*05:142-bearing haplotype is A*02:01~C*05:142~B*44:02. This new allele has a maximum frequency of 0.00001, in 34,743 sequenced-based typed subjects, contrasting with that of C*05:01 (allele frequency 0.10441), in our local, largely UK European, blood donors.

HLA-A*24:374-A novel allele encoding the HLA-A2403 specificity

HLA-A*24:374 differs from A*24:03:01:01 by 2 exon 3 bases resulting in a substitution of T163E.

Two new HLA class I alleles - A*11:241 and C*08:132

HLA-A*11:241 differs from A*11:01:01:01 (215G > A, exon 2, R48Q); HLA-C*08:132 from C*08:02:01:01 (587 T > A exon 3, L172Q).

A novel HLA-B*14 allele - B*14:53 - genetics and serology

HLA-B*14:53 was found in a UK European normal blood donor prior to registration on the Welsh Bone Marrow Donor Registry. It differs from B*14:13 by one base (103G>T) in exon 2 resulting in a substitution of alanine (A) in B*14:13 to serine (S) in B*14:53. Unique among current HLA-B*14 alleles, B*14:53 and B*14:13 share a motif of 59 bases between positions 361 and 419 in exon 3. This motif is present in numerous HLA-B alleles the commonest overall being B*08:01, suggesting that both B*14:53 and B*14:13 arose from intralocus gene conversion events with B*08:01. Thus, B*14:53 probably arose from B*14:01:01 (which has TCC at codon 11 (S), while B*14:13 arose from B*14:02:01:01 which has GCC at codon 11 (A). Additionally, the two likely B*14:53-bearing and B*14:13-bearing haplotypes are typical of B*14:01:01-bearing and B*14:02:01:01-bearing haplotypes, respectively. Serological testing, using 49 antisera with HLA-B64, or B64, B65 reactivity, showed that the B*14:53 specificity did not react as a B64 (B*14:01) specificity and may appear as a short/weak HLA-B14. This implies that residues additional to S at position 11 are involved in HLA-B64 serological identity; for example, the motif 11S 97W 116F is possessed by B*14:01 and many other B*14 products (and B*39:79 plus some HLA-C products) but not B65 (B*14:02) or the B*14:53 specificity. B*14:53 was found in a random HLA sequence-based typed population of 32 530 normal subjects indicating a low precision allele frequency of 0.000015 in subjects resident in Wales.

A new HLA-A*26 family allele--HLA-A*26:103

HLA-A*26:103 differs from A*26:01:01 by one base (559C>G) in exon 3 resulting in an amino acid substitution of R163G.

A group-specific sequence-based typing approach for HLA-DQA1

An HLA-DQA1 sequence-based typing method reliant upon group-specific amplification to achieve an unambiguous second-field DQA1 typing assignment is presented. Method validation, using 51 reference DNA samples covering 21 different DQA1 alleles, showed 100% concordance with the reference types. This typing strategy has several important uses including identifying DQA1 mismatches in kidney donor/recipient pairs to inform patient DQ antibody assignments.

HLA-B*27:05:25 - a further HLA-B*27:05 allele with a synonymous nucleotide substitution

HLA-B*27:05:25 differs from B*27:05:02 by a single synonymous nucleotide substitution (192C>T) at codon 40 in exon 2.

A new HLA-A*01 allele - A*01:139

HLA-A*01:139 differs from A*01:01:01:01 by one nucleotide (383G>C) resulting in an amino acid change of glycine104alanine.

A new HLA-A*03 null allele - A*03:162N caused by an exon 4 insertion and discovered during an external quality assessment exercise

HLA-A*03:162N differs from A*03:01:01:01 by an exon 4, 664-665insCATG causing E198A and A199X.

Comprehensive evaluation of two HLA-B17 monoclonal antibodies for flow cytometry-based HLA-B57/B58 screening prior to abacavir prescription

Hypersensitivity reactions to the drug abacavir, used to treat HIV/AIDS patients, is associated with possession of HLA-B*57:01. We have carefully assessed two commercially available HLA-B57/B58 murine monoclonal antibodies [0196HA and BIH0243 (One Lambda Inc.)] in a simple flow cytometry-based assay. The evaluation involved tests on 228 reference and random samples covering 91% of all WHO recognized HLA-A, B and C specificities. These involved donors with six different HLA-B*57 alleles and included 19 examples of B*57:01. Both antibodies unambiguously detected B57, but there were small difference in their reactivity against B57-positive non-B*57:01 samples. Importantly, there was no reactivity against B57/B58-negative samples. The possible amino acid motifs involved in the reactivity of these antibodies with B57/B58 were delineated. Thus, HLA-B57/B58, normally present in <10% of patients, can be easily recognized using these two antibodies and further tested by a DNA-based typing method to identify B*57:01.

16(th) IHIW: analysis of HLA population data, with updated results for 1996 to 2012 workshop data (AHPD project report)

We present here the results of the Analysis of HLA Population Data (AHPD) project of the 16th International HLA and Immunogenetics Workshop (16IHIW) held in Liverpool in May-June 2012. Thanks to the collaboration of 25 laboratories from 18 different countries, HLA genotypic data for 59 new population samples (either well-defined populations or donor registry samples) were gathered and 55 were analysed statistically following HLA-NET recommendations. The new data included, among others, large sets of well-defined populations from north-east Europe and West Asia, as well as many donor registry data from European countries. The Gene[rate] computer tools were combined to create a Gene[rate] computer pipeline to automatically (i) estimate allele frequencies by an expectation-maximization algorithm accommodating ambiguities, (ii) estimate heterozygosity, (iii) test for Hardy-Weinberg equilibrium (HWE), (iv) test for selective neutrality, (v) generate frequency graphs and summary statistics for each sample at each locus and (vi) plot multidimensional scaling (MDS) analyses comparing the new samples with previous IHIW data. Intrapopulation analyses show that HWE is rarely rejected, while neutrality tests often indicate a significant excess of heterozygotes compared with neutral expectations. The comparison of the 16IHIW AHPD data with data collected during previous workshops (12th-15th) shows that geography is an excellent predictor of HLA genetic differentiations for HLA-A, -B and -DRB1 loci but not for HLA-DQ, whose patterns are probably more influenced by natural selection. In Europe, HLA genetic variation clearly follows a north to south-east axis despite a low level of differentiation between European, North African and West Asian populations. Pacific populations are genetically close to Austronesian-speaking South-East Asian and Taiwanese populations, in agreement with current theories on the peopling of Oceania. Thanks to this project, HLA genetic variation is more clearly defined worldwide and better interpreted in relation to human peopling history and HLA molecular evolution.

HLA gene and haplotype frequencies in Russians, Bashkirs and Tatars, living in the Chelyabinsk Region (Russian South Urals)

We have characterized the HLA-A, -B, -DRB1, -DQA1 and -DQB1 profiles of three major ethnic groups living in Chelyabinsk Region of Russian South Urals, viz., Russians (n = 207), Bashkirs (n = 146) and Tatars (n = 135). First field level typing was performed by PCR using sequence-specific primers. Estimates included carriage and gene frequencies, linkage disequilibrium and its significance and related values. Population comparisons were made between the allele family frequencies of the three populations and between these populations and 20 others using a dendrogram. Chelyabinsk Region Russians demonstrate all the features typical of a Caucasoid population, but also have some peculiarities. Together with Tatars, Russians have high frequencies of allele families and haplotypes characteristic of Finno-Ugric populations. This presupposes a Finno-Ugric impact on Russian and Tatar ethnogenesis. However, this was not apparent in Bashkirs, the first of the three populations to live in this territory, and implies admixture with populations of a Finno-Ugric origin with precursors of Russians and Tatars before they came to the South Urals. The Bashkirs appear close to Mongoloids in allele and haplotype distribution. However, Bashkirs cannot be labelled either as typical Mongoloids or as Caucasoids. Thus, Bashkirs possess some alleles and haplotypes frequent in Mongoloids, which supports the Turkic impact on Bashkir ethnogenesis, but also possess the AH 8.1 haplotype, which could evidence an ancient Caucasoid population that took part in their ethnic formation or of recent admixture with adjacent populations (Russians and Tatars). Bashkirs showed no features of populations with a substantial Finno-Ugric component, for example Chuvashes or Russian Saami. This disputes the commonly held belief of a Finno-Ugric origin for Bashkirs. Tatars appeared close to many European populations. However, they possessed some characteristics of Asiatic populations possibly reflecting a Mongoloid influence on Tatar ethnogenesis. Some aspects of HLA in Tatars appeared close to Chuvashes and Bulgarians, thus supporting the view that Tatars may be descendents of ancient Bulgars.

HLA-B*15:33, a rare allele whose product reacts as an HLA-B62 and -Cw5/Cw8 specificity

Using PCR with sequence-specific primers (SSP) and subsequent sequencing of exons 2 and 3, we identified an example of B*15:33 in a likely north-western European Caucasoid volunteer haemopoietic stem cell (HSC) donor. This was only the second example submitted to the IMGT/HLA database since B*15:33 was first described in 1996. B*15:33 differs from B*15:01:01:01 by three nucleotides resulting in two amino acid differences with B*15:01 (131S>R, 138T>K). This allele encodes a typical HLA-B62 specificity--as confirmed using 17 local antisera from parous women and 19 monoclonal antibodies directed towards B15, B62 and B63 specificities. Importantly, it also reacted as a Cw5/Cw8 specificity when tested against 21 Cw5, Cw5/Cw8 and Cw8 antisera. This Cw5/Cw8 reactivity is probably due to the B*15:33 specificity having lysine at position 138 which is possessed by numerous C*05 and many C*08 products. B*15:33 is likely to have derived from a HLA-B/C inter-locus gene conversion event. HLA-B*15:33 is clearly rare--this single example was found during the HLA PCR-SSP-based typing of 57,079 potential HSC donors. This indicates an allele frequency of <0.00001 in blood donors resident in Wales. An Epstein-Barr virus transformed B-cell line from the HLA-B*15:33 donor is available.

A new HLA-C allele, C*08:43, identified during a UCLA Immunogenetics Centre cell exchange

HLA-C*08:43 differs from HLA-C*08:02:01 by one nucleotide (A>G) at position 584 resulting in an amino acid change of 171 tyrosine to 171 cysteine.

A novel HLA-B*40 sequence--B*40:92

A new allele, HLA-B*40:92, was identified in a north-western European subject during polymerase chain reaction using sequence-specific priming (PCR-SSP)-based typing of haematopoietic stem cell (HSC) donors. B*40:92 differs from B*40:01:01 by six nucleotides at positions 559, 560, 603, 605, 610 and 618 in exon 3 which represents a substitution motif of at least 60 nucleotides. This motif, which occurs in numerous HLA alleles including the relatively high frequency B*15 and B*35 allele families, encode four amino acid changes at positions 163 (glutamic acid > leucine), 177 (aspartic acid > glutamic acid), 178 (lysine > threonine), 180 (glutamic acid > glutamine) and a silent substitution, conserved alanine, at codon 182. Thus, it is likely that HLA-B*40:92 occurred following a gene conversion-like or interallelic recombination event involving B*40:01:01 and probably a B*15 or more likely a B*35 family allele. HLA-B*40:92 was found on a haplotype with HLA-A*02:01, B*40:92, C*03:04, DRB1*13:02, DRB3*03:01, DQA1*01:02, DQB1*06:04, DPA1*02:02, DPB1*05:01. Tests on 69 selected B40 and B35 antisera and Lambda Monoclonal Trays™ show that B*40:92 encodes a 'short' B40/B60 serological specificity which displays some HLA-B35 reactivity. The HLA-B40 and HLA-B35 motifs (possible epitopes) responsible for this serological reactivity were identified. This single example of HLA- B*40:92 was found in 56,823 consecutive HLA PCR-SSP typed HSC donors indicating a carriage frequency of 0.00176% (allele frequency 0.00001) in blood donors resident in Wales. An Epstein-Barr virus transformed B-cell line from the HLA-B*40:92 donor is available.

A new HLA-C allele: Cw*0819

Human leucocyte antigen-Cw*0819 differs from Cw*0802 by two nucleotides resulting in an amino acid change of 99tyrosine to 99phenylalanine and a synonymous substitution.

A new HLA-B*08 variant--B*0838

HLA-B*0838 differs from B*080101 by three nucleotides resulting in an amino acid change of 63asparagine to 63glutamic acid and a synonymous substitution.

HLA antigens and Bf allotypes in lichen sclerosus et atrophicus

A study of the HLA-A, B and DR antigens and properdin factor B allotypes of 26 patients with lichen sclerosus et atrophicus and a normal control population showed an increase in the HLA-Aw31 antigen only. However, when the HLA-A and B frequencies were combined with the results of a previous independent study a significant increase in both HLA-Aw31 and HLA-B40 was noted. These findings suggest an association between lichen sclerosus et atrophicus and the HLA system.

Two new HLA-C alleles: Cw*0222 and Cw*0434

HLA-Cw*0222 differs from Cw*020202 by three nucleotides at codons 114, 116 and 127, while HLA-Cw*0434 differs from Cw*0408 by two nucleotides at codons 152 and 156.

Fine mapping of the MHC Class III region demonstrates association of AIF1 and rheumatoid arthritis

OBJECTIVES

The heritability of RA has been estimated to be approximately 55%, of which the MHC contributes about one-third. HLA-DRB1 alleles are strongly associated with RA, but it is likely that significant non-DRB1 MHC genetic susceptibility factors are involved. Previously, we identified two three-marker haplotypes in a 106-kb region in the MHC class III region immediately centromeric to TNF, which are strongly associated with RA on HLA-DRB1*0404 haplotypes. In the present study, we aimed to refine these associations further using a combination of genotyping and gene expression studies.

METHODS

Thirty-nine nucleotide polymorphisms (SNPs) were genotyped in 95 DRB1*0404 carrying unrelated RA cases, 125 DRB1*0404-carrying healthy controls and 87 parent-case trio RA families in which the affected child carried HLA-DRB1*04. Quantitative RT-PCR was used to assess the expression of the positional candidate MHC class III genes APOM, BAT2, BAT3, BAT4, BAT5, AIF1, C6orf47, CSNK2beta and LY6G5C, and the housekeeper genes, hypoxanthine-guanine phosphoribosyltransferase (HPRT) and beta(2)-microglobulin (B2M) in 31 RA cases and 21 ethnically, age- and sex-matched healthy controls. Synovial membrane specimens from RA, PsA and OA cases were stained by an indirect immunoperoxidase technique using a mouse-anti-human AIF1 monoclonal antibody.

RESULTS

Association was observed between RA and single markers or two marker haplotypes involving AIF1, BAT3 and CSNK. AIF1 was also significantly overexpressed in RA mononuclear cells (1.5- to 1.9-fold difference, P = 0.02 vs HPRT, P = 0.002 vs B2M). AIF1 protein was clearly expressed by synovial macrophages in all the inflammatory synovial samples in contrast to the non-inflammatory OA samples.

CONCLUSIONS

The results of the genotyping and expression studies presented here suggest a role for AIF1 in both the aetiology and pathogenesis of RA.

A new HLA-B*15 variant - B*9507

The human leukocyte antigen-B*15 variant B*9507 is similar to B*1505 (B62) but with substitutions of A>C at position 463 and G>C at position 477 in exon 3. This results in a single amino acid change of serine to arginine (AGC>CGC) at codon 131 and a silent substitution (GCG>GCC - conserved alanine) at codon 135.

Non-B27 MHC associations of ankylosing spondylitis

Ankylosing spondylitis (AS) has been associated with human leukocyte antigen (HLA)-B27 for over 30 years; however, the mechanism of action has remained elusive. Although many studies have reported associations between AS and other genes in the major histocompatibility complex (MHC) in AS, no conclusive results have emerged. To investigate the contribution of non-B27 MHC genes to AS, a large cohort of AS families and controls were B27 typed and genotyped across the region. Interrogation of the data identified a region of 270 kb, lying from 31 952 649 to 32 221 738 base pairs from the p-telomere of chromosome 6 and containing 23 genes, which is likely to include genes involved with susceptibility to AS.

A high-resolution polymerase chain reaction-sequence-specific primer HLA-B*27 typing set and its application in routine HLA-B27 testing

We designed a set of 35 polymerase chain reaction sequence-specific primers (PCR-SSP) in 29 SSP mixtures to assign 29 HLA-B*27 4-digit level alleles (B*2701-B*2721 and B*2723-B*2730). This was used in conjunction with our 41 PCR-SSP primer mixture low-resolution HLA-B typing set to fully differentiate B*27 from all other HLA-B alleles. Successful typing set validation used 521 B*27 samples covering 13 (B*2701-B*2710 and B*2712, B*2717, B*2723) alleles. The distribution of B*27 alleles was determined in a random population of 4020 local blood donors and the use of PCR-SSP B*27 typing in our routine flow cytometry-based HLA-B27/B2708 typing strategy is described.

A typing system for the major histocompatibility complex class I chain related genes A and B using polymerase chain reaction with sequence-specific primers

The Major Histocompatibility Complex (MHC) class I chain related (MIC) A and B genes are important additional loci within the MHC. We have developed a MICA and MICB typing system using the polymerase chain reaction with sequence-specific primers (PCR-SSP), which operates under the same conditions as our routine HLA-A, -B, and -C typing method. We designed 95 primers in 84 SSP mixtures for MICA and 39 primers in 29 mixtures for MICB. This detected and differentiated all 55 MICA and 19 MICB alleles (except MICA*00701 from MICA*026, MICA*00201 from MICA*020, and three MICB alleles, which are intronic variations). A computer program confirmed the MICA amplification reactivity of each SSP mixture and evaluated the typing set for MICA allele combination ambiguities. Seventy-six "reference" DNA samples were used for validation: 50 from International Histocompatibility Workshop B lymphoblastoid cell lines (IHW BCLs) and 26 MICA-typed samples from two laboratories. The reference material identified 28 out of the 55 MICA alleles and 13 of the 19 MICB alleles, and directly validated 62 of the 84 MICA and 20 of the 29 MICB SSP mixtures. Our genotyping agreed with 283 out of the 286 (98.95%) MICA and MICB reference laboratories' allele assignments or the consensus assignments. Two of the discrepancies remain unresolved, whereas one was probably due to a reference laboratory's failure to differentiate alleles differing in exon 5 of the MICA gene. A comparison of the MICA and MICB allele assignments between laboratories identified a "disagreement rate" of 19.4% for MICA alleles and 13.1% for MICB alleles. Accordingly, we have compiled "consensus" MICA and MICB genotypes for the 50 IHW BCLs tested, which have been confirmed by our typing. We also typed 166 random blood donors. Their MICA and MICB carriage and allele frequencies and HLA-B, MICA, MICB linkage disequilibrium parameters and haplotype frequencies largely concurred with other published data on United Kingdom subjects, further supporting the validity of our typing system. This PCR-SSP system is a simple, reliable and rapid technique for typing MICA and MICB alleles. It is easily updated as new alleles are identified but clearly requires a continuing validation review until all known MICA and MICB alleles have been identified.

Identification of a novel HLA-A allele (A*1115) in the UK National External Quality Assessment Schemes for Histocompatibility and Immunogenetics' Educational Cell Exchange

The novel allele, HLA-A*1115, was identified in an 'Educational Scheme' sample (ED03/03 - from a north-western European Caucasoid blood donor) distributed by the UK National External Quality Assessment Schemes for Histocompatibility and Immunogenetics. ED03/03 was typed by serology, the polymerase chain reaction using sequence-specific primers and sequence-based typing. A*1115 is most similar to A*110101 with a single mismatch (G to C) at constant position 565, leading to a conservative amino acid change from valine (GTG) to leucine (CTG) at codon 165 in the alpha(2) domain. This substitution has not been reported for any other HLA class I allele so far. The HLA-A*1115-bearing haplotype was B*350101; Cw*040101; DRB1*140101; DRB3*020201; DQA1*010401; DQB1*0503; DPA1*0103/07; DPB1*030101. Extensive serological typing indicated that this allele essentially encodes a 'normal' HLA-A11 specificity.

Five-locus HLA typing of hematopoietic stem cell donor volunteers using PCR sequence specific primers

We have developed a strategy for five-locus human leukocyte antigen (HLA) typing of hematopoeitic stem cell (HSC) donors using the polymerase chain reaction with sequence-specific primers (PCR-SSP). The PCR-SSP method is robust, reproducible, and accurate. New PCR-SSP mixtures can be added as required and all reactions are carried out under the same conditions, which can easily be applied to the typing of other loci, e.g., ABO blood groups. Initially, 127 PCR-SSP reactions were used to detect simultaneously HLA-A, -B, -C, -DRB1/3/4/5, and DQB1 alleles, differentiated generally to the level of the first two digits of the allele name, essentially equivalent to the serological split specificity. Approximately 40% of subjects were tested against a further 29 HLA-A, -B SSP mixtures to exclude rare alleles and unambiguously assign a two-digit HLA allele family. This gave an overall typing resolution equivalent to or greater than the split specificity level and covered all HLA-A, -B, -C, -DRBland DQB1 alleles listed in the WHO's Nomenclature for Factors of the HLA System, 2000. The Welsh Bone Marrow Donor Registry has used this strategy to HLA type over 35,000 HSC donors over 9 years. Comprehensive and accurate five-locus HLA typing allows confident and rapid identification of potential matched HSC donors for patients requiring stem cell transplantation generally without the need for typing additional loci. This allows resources to be focused directly on allele level typing of DRB1 and other loci. This strategy decreases overall donor work-up time, which is a major benefit to patients.

Human leucocyte antigen polymorphisms in nut-allergic patients in South Wales

BACKGROUND

Peanuts and tree nuts are among the most common foods provoking severe allergic reactions including fatal anaphylaxis. However, little is known of the underlying genetic and immunological mechanisms involved.

OBJECTIVE

Based on findings in other allergic diseases, we have investigated whether specific human leucocyte antigens (HLA) are associated with nut allergy.

METHOD

Eighty-four patients presenting at the allergy clinic with symptoms of nut allergy were typed for the HLA Class I (HLA-A and B) and Class II (HLA-DRB1 and DQB1) loci by PCR using sequence-specific primers. Carriage frequencies were compared with 82 atopic non-nut-allergic subjects and 1798 random blood donors.

RESULTS

The frequency of HLA-B(*)07 (28.57%) and DRB1(*)11 (15.48%) was increased in the nut-allergic patients compared to the atopic controls (12.20% and 3.66%, respectively) but not when compared to the blood donors (28.86% and 10.12%). DRB1(*)13 and DQB1(*)06 were both increased in frequency in the nut allergy patients over both the atopic and blood donor controls. However, none of these increased frequencies were significant when corrected for the number of comparisons undertaken.

CONCLUSION

At HLA '2-digit resolution' and with undifferentiated patients with nut allergy, there are no major disturbances in the frequency of HLA-A, B, DRB1 or DQB1 types. However, the difference in frequency of HLA-DRB1(*)11 between the nut allergy patients and the atopic controls merits further investigation as this may represent an important phenotypic relationship.

HLA-A*24020102L in the UK blood donor population

The low-expression allele HLA-A*24020102L was identified on a likely haplotype bearing B*55, Cw*01 during the investigation of nine cases (four families and five unrelated subjects) of HLA-A*24 lacking the A24 specificity. A search was made of 70,007 HLA-A, HLA-B, and HLA-C DNA-based typed largely northwestern European Caucasoid blood donors on the British Bone Marrow Registry and Welsh Bone Marrow Donor Registry panels for phenotypes possessing A*24, B*55, Cw*01. Fifty three were found, and 12 of these were subsequently shown to possess A*24020102L by sequence-based typing or polymerase chain reaction with sequence-specific primers. This indicated that the likely A*24, B*55, Cw*01 haplotype has a frequency of 0.000378 in the UK and that approximately 22.6% of these will possess A*24020102L. Consequently, HLA-A*24020102L, B*55, Cw*01 is a principal A*24020102L-bearing haplotype, and the minimum carriage and gene frequencies of A*24020102L are 0.017% and 0.000086, respectively, in UK blood donors.

Provision of Epstein-Barr virus-transformed B-cell lines in a routine tissue typing laboratory: practicalities and applications

A bank of Epstein-Barr virus (EBV)-transformed B-lymphoblastoid cell lines (BCLs) has been established in this laboratory over the last 7 years. Novel, rare and unusual HLA phenotypes were highlighted during routine clinical testing and during typing of volunteer haematopoietic stem cell donors for the Welsh Bone Marrow Donor Registry. The BCLs are routinely used as laboratory reagents, as a source of DNA for reference purposes and for research work. Consenting donors are tested for hepatitis B surface antigens (HBsAg), human immunodeficiency virus (HIV) and hepatitis C virus (HCV) before their B-lymphocytes are transformed. Strict bio-identity checks are performed before and after transformation and after each BCL expansion. Each BCL is tested regularly for mycoplasma contamination. A total of 230 blood samples were transformed. One hundred and fifty-nine sterile samples produced 157 BCLs (98.7% success), while 71 non-sterile samples produced 50 BCLs (70.4% success), giving an overall success rate of 90.0%. Fifteen of the transformation failures have since been repeated successfully. Factors contributing to the high success rate and reasons for the 23 failed transformations are discussed. The successful development and use of pools of BCLs for HLA antibody screening by flow cytometry are described. Whilst certain training and health and safety issues require close attention, it is clear that EBV transformation of B lymphocytes and/or the use of BCLs is feasible in a routine tissue typing laboratory and that BCLs are a valuable resource. Careful adherence to the methods and procedures detailed here should virtually guarantee successful transformation (98.7%) from good quality, sterile whole blood samples.

Immunogenetics of a new HLA-B null allele, HLA-B*4423N

The second example of an HLA-B*44 null allele (B*4423N) was identified by discrepancies between serological and polymerase chain reaction-sequence-specific primer (PCR-SSP) typing in two north-western European Caucasoid unrelated stem cell donor volunteers. HLA-B*4423N was identical to B*440201 except for a single nucleotide substitution at position 493 in exon 3, resulting in a premature stop codon at bases 493-495 (TAG rather than CAG at codon 141). As expected, comprehensive serological testing using 54 antisera, directed towards B44 or Bw4, failed to identify the HLA-B44 (Bw4) specificity. The B*4423N-bearing haplotype was identified as A*0201, Cw*0501, DRB1*0408, DRB4*01, DQA1*03, DQB1*0304 and the frequency of B*4423N estimated as 0.00006 (carriage frequency 0.0121%) in 16 533 subjects resident in Wales.

Immunogenetics of two new HLA-B alleles: B*4414 and B*5708

Two new alleles, HLA-B*4414 and B*5708, were identified in north-western European Caucasoid blood donors. B*4414 differed from B*440201 by two nucleotide substitutions in exon 3 [positions 66 (T to C) and 69 (G to A)] producing two amino acid differences between the B*440201 and B*4414 specificities (tyrosine to histidine at codon 113 and aspartic acid to asparagine at codon 114). B*5708 differed from B*570101 by a single substitution (G to C) at position 247 in exon 2 causing an amino acid difference between B*570101 and B*5708 products of arginine to proline at codon 83. The likely haplotypes bearing these alleles were identified. Both alleles occurred once in approximately 25,000 random blood donors so both have a frequency of approximately 0.00002 (carriage frequency 0.004%). B*4414 and B*5708 specificities both gave 'short' serological reactivity for their expected specificities and Bw4. The likely reasons for this are discussed in relation to the epitopes of B44 and B57.