Complete inherited deficiency of the fourth complement component in a child with systemic lupus erythematosus and his disease-free brother in a North African family

Although null alleles of complement C4 genes (C4A ^*Q0 andC4B ^*Q0) are frequent in the normal population, the occurrence of two null alleles on the same chromosome is very rare and therefore complete C4 deficiency is exceptional. We describe a 16-year-old North African boy who presented with systemic lupus erythematosus with renal involvement and persistent undetectable classical pathway activity and C4 protein and hemolytic activity in plasma, with normal C3 levels. Similar complement abnormalities were observed in his healthy 12-year-old brother. Complete C4 deficiency was documented in the two brothers by investigation of the family and the lack of C4A and C4B bands upon phenotyping of C4. Southern blot analysis of the C4/CYP21 gene organization in the family indicated that the deficiency resulted from a deletion of the C4B/CYP21A genes associated with nonexpression of a C4A gene. The double-null haplotype was found to be associated with homozygous A2 B17 C2C BFF C4 AQO BQO DR7 HLA haplotype. Thus, similar C4 deficiencies with HLA identity may lead to different clinical presentations.     

C2_4_4 microheterogeneity and HLA Class I

The microheterogeneity of the tetranucleotide repeat locus C2_4_4 situated in the HLA class I region (6p21.3) was investigated by sequencing 50 alleles in an Austrian population sample of 240 unrelated Caucasoid individuals. Several different sequences were found in alleles of the same length. Analysis of the associations between the sequenced C2_4_4 alleles and HLA class I showed a strong linkage disequilibrium between the C2_4_4*9 sequence variants and two different HLA class I haplotypes, as well as between the most common *17 sequence and one HLA-ABC haplotype. No clear cut association could be observed in C2_4_4*16 and *18. The results of this study demonstrate that the exclusive use of microsatellite polymorphisms for the definition of HLA haplotypes is generally not possible.     

Description of two new HLA‐C alleles: C*08:63 and C*14:44

Here, we present two new HLA allelic variants at C locus: HLA‐C*08:63 and HLA‐C*14:44 detected by sequence‐based typing. In both cases, a single‐nucleotide mutation in exon 3 is responsible for a change in aminoacid translation. The extremely high polymorphism of human leucocyte antigen (HLA) system in human genome is responsible for the capability to recognize different antigens, including non‐self‐MHC (Major Histocompatibility Complex) molecules. This very high polymorphism and the improving accuracy of genomic HLA typing methods lead to an exponential increasing of known HLA alleles. Here, we describe the characterization of two new HLA‐C alleles identified by sequence‐based typing (SBT): HLA‐C*08:63 and HLA‐C*14:44.     

The HLA Dictionary 2001: a summary of HLA‐A, ‐B, ‐C, ‐DRB1/3/4/5 and ‐DQB1 alleles and their association with serologically defined HLA‐A, ‐B, ‐C, ‐DR and ‐DQ antigens

This report presents the serological equivalents of 123 HLA‐A, 272 HLA‐B and 155 HLA‐DRB1 alleles. The equivalents cover over 64% of the presently identified HLA‐A, ‐B and ‐DRB1 alleles. The dictionary is an update of the one published in 1999 (^<1>Schreuder et al., 1999, Tissue Antigens, 54 , 409) and also includes equivalents for HLA‐C, DRB3, DRB4, DRB5 and DQB1 alleles. The data summarize information obtained by the WHO Nomenclature Committee for Factors of the HLA System, the International Cell Exchange (UCLA), the National Marrow Donor Program (NMDP) and individual laboratories. In addition, a listing is provided of alleles that are expressed as antigens with serological reaction patterns that differ from the well‐established HLA specificities. The equivalents provided will be useful in guiding searches for unrelated hematopoietic stem cell donors in which patients and/or potential donors are typed by either serology or DNA‐based methods. These equivalents will also serve typing and matching procedures for organ transplant programmes where HLA typings from donors and from recipients on waiting lists represent mixtures of serological and molecular typings. The tables with HLA equivalents and a questionnaire for submission of serological reaction patterns for poorly identified allelic products will also be available on the WMDA web page: www.worldmarrow.org     

Late onset 21-hydroxylase deficiency and HLA in the Ashkenazi population: A new Allele at the 21-hydroxylase locus

The congenital form of 21-hydroxylase deficiency (21-OH-def), which results in virilization at birth from intrauterine exposure to testosterone, results from the inheritance of an HLA-linked recessive disease allele from each parent a t the 21-OH locus (the 21-OH⁰ allele). In this study we establish a relationship between intermediate and late onset 21-OH-def and HLA. In studies of five Ashkenazi families, we concluded that these syndromes can be caused by either of two combinations of genes at the 21-OH locus: They can occur in individuals who carry the 21-OH⁰ allele on one baplotype and who in addition inherit a “susceptibility” 21-OH-def gene (21-OH⁸) from their other parent (genotype = 21-OH⁰/21-OH³; or they can occur in individuals who are homozygous for the “susceptibility” 21-OH-def allele (21-OH⁸/21-OH³). The biochemical abnormality in late onset 21-OH-deficiency is characterized by elevated basline levels of plasma 17-hydroxyprogesterone (17-OH-P) and urinary pregnanetriol and/or relatively high 17-OH-P following ACTH stimulation. Although clinical symptoms are not always present in all family members with this biochemical abnormality, the abnormality appears to behave as a simple autosomal recessive trait that is linked to HLA.Among the five probands studied, eight of the eight haplotypes from five nonconsaguinous families assumed to carry the 21-OH³ allele had the HLA antigens B14 and DRwl and also had the factor B (Bf) S (Slow) variant. The two remaining disease haplotypes were assumed from biochemical data to carry 21-OH⁰ alleles. The results suggest that the biochemical abnormality in these syndromes is linked to HLA and that the 21-OH³ allele has nonrandom association with the particular HLA haplotype B14, DRwl, BfS in the Ashkenazi population.     

Circulating T lymphocyte subsets in coeliac disease (CoD) patients and healthy family members

Increased proportions of circulating antigen-primed CD45RO⁺ TCR γδ cells have been found in untreated CoD patients. As certain immunological features are now found in both CoD and healthy persons carrying the HLA DQ2 heterodimer, we sought to establish whether healthy members of the families of CoD patients who are positive for HLA DQ2 and also have increased densities of TCR γδ intraepithelial lymphocytes (IEL) in their small bowel mucosa have elevated levels of circulating TCR γδ memory cells. Peripheral blood T cells were analysed by flow cytometry in 22 patients with CoD and 16 healthy family members. Untreated CoD patients had higher percentages of circulating CD45RO⁺ TCR γδ cells and CD45RO⁺ Vδ1⁺ cells than healthy family members. On the other hand, the amount of circulating Vδ1⁺ lymphocytes was lower in patients with CoD compared with healthy family members. In contrast, no differences were found between HLA DQ2⁺ and HLA DQ2^? healthy family members in respect of circulating TCR γδ cell subsets. The change in circulating TCR γδ cell subsets found in patients with CoD is thus a consequence of an ongoing immunological process which diminishes on a gluten-free diet rather than a phenomenon directly caused by DQ2. These changes in peripheral blood are not found in healthy individuals who have the same HLA alleles DQA1*0501 and DQB1*0201 encoding the HLA DQ2 and who also have increased densities of TCR γδ IEL in their otherwise normal jejunal mucosa.     

INHERITED STRUCTURAL VARIATION AND LINKAGE RELATIONSHIPS OF C7

Three structural forms of C7 have been distinguished by isoelectric focusing. They are the products of three co-dominantly expressed alleles at an autosomal locus. The C7 locus is close to that for C6, but is not close to the HLA complex.     

A peptide derived from hepatitis C virus (HCV) core protein inducing cellular responses in patients with HCV with various HLA class IA alleles

C35‐44 peptide is a well known HLA‐A2‐restricted CTL epitope originating from hepatitis C virus (HCV) core protein. It was reported that the majority of HCV positive patients had significant levels of serum IgG specific to this peptide. This study addressed whether C35‐44 peptide could induce CTL activity restricted to various HLA class IA alleles or could not. This peptide demonstrated binding activity to HLA‐A*2402, ‐A*2601, ‐A*3101, and ‐A*3303 molecules, but not to HLA‐A*1101 by means of stabilization assay. This peptide also induced CTL activity restricted to each of them, except HLA‐A11⁺ peripheral blood mononuclear cells from HCV 1b⁺ patients by means of ⁵¹Cr‐release assay. With regard to HLA‐A2 subtypes, this peptide demonstrated binding activity to HLA‐A*0201 and ‐A*0206, but not to ‐A*0207 molecules. Furthermore, this peptide induced CTL activity from both the patients and healthy donors with all the HLA class IA molecules mentioned above by means of interferon‐γ production assay. These results may provide new insights for the development of a novel peptide vaccine against HCV compatible with various HLA class IA types. J. Med. Virol. 81:1232–1240, 2009. © 2009 Wiley‐Liss, Inc.     

Distribution of HLA‐DRB1 and HLA‐DQB1 families of alleles and haplotypes in Vojvodina population

Major histocompatibility complex encoding human leucocyte antigens (HLA) is a highly polymorphic gene cluster that makes it a valuable tool in the population genetic studies. The aim of our study was to compare HLA class II gene frequencies with other populations from Europe and to determine the relationship between the investigated populations. In this study, one hundred and twenty healthy individuals from Vojvodina, northern Serbia, were studied for 18 of the HLA‐DRB1 and HLA‐DQB1 loci. The HLA families of alleles were analysed by using sequence‐specific primers for polymerase chain reaction (PCR‐SSP). The results showed the increased frequency of HLA‐DRB1*11(0.333), ‐DRB1*04(0.300), ‐DRB1*07(0.250), ‐DQB1*03(0.730) and ‐DQB1* 05(0.391), among the tested families of alleles. The two‐locus haplotype analysis revealed significant positive linkage disequilibrium for DRB1*11DQB1*03 (Δ = 0.0788, χ² = 12.61) and DRB1*04DQB1*03 (Δ = 0.0583, χ² = 8.04). A phylogenetic tree constructed on the basis of the DRB1* gene frequencies derived from other populations revealed the clustering among the Vojvodina population together with other populations in Europe (Croats, Austrians and Hungarians). Close relationship of the Vojvodina population with the populations of Hungarians and Austrians can be the result of their historical influence on the region of Vojvodina.     

Different HLA antigen associations for the functionally active and inactive products of the complement C4F1 allele

The genetic polymorphism of the fourth component of human complement. C4, was studied in 945 unrelated Caucasian individuals. A third allele of the C4F (Rodgers) locus, termed C4F₁ was demonstrated. This allele is characterized using immunofixation electrophoresis, by the presence of an additional fast-moving anodal band of C4 which distinguishes it clearly from the common C4F variant. The allelic frequencies fit the Hardy-Weinberg equilibrium assuming three alleles at the C4F locus: C4F, C4f⁰, and C4F₁. The functional activity of the C4F variants was investigated using a specific hemolytic overlay technique for C4. It was found that in almost all individuals (75 out of 78), the C4F₁ allele codes for a functionally inactive C4 product only when it occurs on an HLA-B17 positive haplotype but that the same allele codes for a functionally active fast variant of C4 when it occurs on an HLA-B37 positive haplotype (18 out of 18). Very strong genetic linkage disequilibrium was observed for the C4F₁ allele with HLA-B17 and B37. The active and inactive C4F₁ variant also has marked nonrandom gametic association to different alleles of the of locus and to HLA-C locus determinants. No further variants of the C4S (Chido) locus have been identified so far. Rodgers (Rg) typing by the plasma inhibition test of anti-Rg antiserum has shown that plasma from individuals homozygous for the C4F₁ allele is only able to partially inhibit anti-Rg whereas all C4F positive individuals totally inhibited the reaction.     

HLA-A, B and C Antigens in South Indian Families with Leprosy

Seventy-two families, selected for having at least two children affected with leprosy, were HLA typed for 57 A, B and C locus antigens recognized by the WHO Nomenclature Committee. In addition, 20 possible new "splits" were investigated. The distribution of A, B and C locus antigens in affected and unaffected family members was similar, irrespective of the type of leprosy in the family. Gene frequencies (derived by direct gene counting from 253 haplotypes), haplotype frequencies and delta values were calculated. There is evidence for heterogeneity of B5, B15, B17, Bw16 and Bw35 and for the existence of at least one A locus and one B locus antigen not previously detected. The value of the HLA system for detecting expaternal children in a highly inbred population and the effect of inbreeding on the HLA system is discussed.     

Differences in HLA class II alleles of isolated South American Indian populations from Brazil and Argentina

We have studied the HLA class II alleles in 277 South American Indians, which included Argentinian tribes from the Gran Chaco: Toba (n = 135), Toba-Pilaga (n = 19), Mataco-Wichi (n = 49), and Xavantes, a tribe from Central Brazil (n = 74). In the Brazilian tribe, only four DR groups were found: DRB1^*1602 (gf = 0.303), DRB1^*04 including DRB1^*0404 (gf = 0.070) and DRB1^*0407 (gf = 0.077), DRB1^*0802 fgf = 0.265), and DRB1^*1402 (gf = 0.303). The HLA class II allele frequencies were similar among the different Argentinian tribes, and 90% of DRB1 alleles belonged to three families: DRB1^*04 (including DRB1^*0403, DRB1^*0404, DRB1^*0407, DRB1^*0411, and DRB1^*0417), DRB1^*0802, and DRB1^*14 (including DRB1^*1402 and DRB1^*1406). At the DPB1 locus, we found only seven alleles, the most frequent being DPB1^*0402. Comparison of HLA class II alleles with those of North American Indians that we have previously studied shows that the frequency of some HLA class II alleles in Brazilian Xavantes resembles that of North American Indians more than that of the Argentinian Indian tribes. The allele DRB1^*0417 was found exclusively in this population.     

High-resolution HLA-A,HLA-B,and HLA-DRB1 haplotype frequencies from the French Bone Marrow Donor Registry

We have estimated human leukocyte antigen (HLA) haplotype frequencies using the maximum likelihood mode, which accommodates typing ambiguities. The results of the frequency distribution of the 7015 haplotypes obtained are presented here. These include a total of 114 HLA-A, 185 HLA-B, and 76 HLA-DRB1 unique alleles at each locus. Across all populations, although the most common individual HLA alleles were HLA-A¹02:01 (29.0%), HLA-B¹07:02 (11.4%), and HLA-DRB1¹07:01 (15.9%), the most frequent haplotype was found to be HLA-A¹01:01∼B¹08:01∼DRB1¹03:01.     

Increased frequency and function of KIR2DL1–3+ NK cells in primary HIV‐1 infection are determined by HLA‐C group haplotypes

The acquisition and maintenance of NK‐cell function is mediated by inhibitory killer‐cell immunoglobulin‐like receptors (KIRs) through their interaction with HLA class I molecules. Recently, HLA‐C expression levels were shown to be correlated with protection against multiple outcomes of HIV‐1 infection; however, the underlying mechanisms are poorly understood. As HLA‐C is the natural ligand for the inhibitory receptors KIR2DL1 and KIR2DL2/3, we sought to determine whether HLA‐C group haplotypes affect NK‐cell responses during primary HIV‐1 infection. The phenotypes and functional capacity of NK cells derived from HIV‐1‐positive and HIV‐1‐negative individuals were assessed (N = 42 and N = 40, respectively). HIV‐1 infection was associated with an increased frequency of KIR2DL1–3⁺ NK cells. Further analysis showed that KIR2DL1⁺ NK cells were selectively increased in individuals homozygous for HLA‐C2, while HLA‐C1‐homozygous individuals displayed increased proportions of KIR2DL2/3⁺ NK cells. KIR2DL1–3⁺ NK cells were furthermore more polyfunctional during primary HIV‐1 infection in individuals also encoding for their cognate HLA‐C group haplotypes, as measured by degranulation and IFN‐γ and TNF‐α production. These results identify a novel relationship between HLA‐C and KIR2DL⁺ NK‐cell subsets and demonstrate that HLA‐C‐mediated licensing modulates NK‐cell responses to primary HIV‐1 infection.     

Human leukocyte antigen matching and fetal loss: results of a 10 year prospective study

The role that maternal and fetal human leukocyte antigen (HLA) genes play in pregnancy is unknown, but it has been suggested that fetuses whose HLA alleles do not differ from maternal alleles (i.e. histocompatible fetuses) are more likely to be aborted than fetuses with HLA alleles that differ from maternal alleles (i.e. histoincompatible fetuses). To elucidate the role of HLA compatibility in pregnancy, we tested the hypothesis that couples who match for HLA alleles or haplotypes would have reduced fertility because only these couples could produce histocompatible fetuses. We conducted a 10 year prospective study of HLA matching and pregnancy outcome in 111 Hutterite couples, providing information on 251 pregnancies. A logistic regression analysis was performed to determine the effects of HLA matching at HLA regions and loci on pregnancy outcome (fetal loss versus delivery). Significantly increased fetal loss rates were observed among couples matching for the entire 16-locus haplotype (P = 0.002). Among the individual loci, loss rates were increased among couples matching for HLA-B (P = 0.019), HLA-C (P = 0.033) and the complement component, C4 (P = 0.043). We interpret these results as evidence that matching for the entire 16-locus haplotype and/or alleles at an HLA-B-linked locus confers significant risk for fetal loss.      

HLA ANTIGEN STUDIES IN A FAMILY WITH C2 DEFICIENCY

Two children in a family were found to be homozygous for C2 deficiency; both parents and a third child were heterozygous. C2 deficiency was associated with the HLA haplotypes carrying the antigens B18 and DW2. Antigen A10 was absent in this family. Mixed lymphocyte culture studies among the family members confirmed the association of C2 deficiency with the HLA-D locus.     

HLA antigen studies in a family with C2 deficiency.

Two children in a family were found to be homozygous for C2 deficiency; both parents and a third child were heterozygous. C2 deficiency was associated with the HLA haplotypes carrying the antigens B18 and DW2. Antigen A10 was absent in this family. Mixed lymphocyte culture studies among the family members confirmed the association of C2 deficiency with the HLA-D locus.     

Association of Sj?gren's syndrome with C4 deficiency,defective reticuloendothelial function and circulating immune complexes.

A case of Sjögren's syndrome with the sicca complex is presented which was associated with persistently low or absent C4 levels, high levels of circulating immune complexes and abnormal reticuloendothelial clearance of damaged or IgG antibody sensitized autologous red blood cells (RBCs). Investigation of normal relatives of the patient revealed low C4 levels and abnormal reticuloendothelial clearance of damaged or sensitized RBCs. HLA, A, B, DR typing revealed a high incidence of the HLA B8, DR3 haplotype and of homozygous null alleles at the C4A locus in the family members. These results suggest that the C4 deficiency and the abnormal reticuloendothelial function in the patient was in part genetically determined and may have predisposed to the development of Sjögren's syndrome. These findings serve to emphasize the possible importance of abnormal macrophage function in the pathogenesis of Sjögren's syndrome and suggest that further investigation of these aspects may increase understanding of this disease.     

Analysis of the complete genomic sequence of HLA‐A alleles in the Chinese Han population

To analyse the complete genomic sequences and investigate the intron polymorphism of the human leucocyte antigen (HLA)‐A locus, the full‐length nucleotide sequences of each major allelic group of HLA‐A in the Chinese Han population were determined, including HLA‐A*01, A*02, A*03, A*11, A*23, A*24, A*26, A*29, A*30, A*31, A*32, A*33, A*34, A*68, A*69. More than 3.0‐kb DNA fragment of HLA‐A locus was amplified from 5′‐untranslated region to 3′‐noncoding region for sequencing. Full‐length sequences of the HLA‐A alleles were determined using an ABI BigDye^® Terminator Cycle Sequencing kit and the HLA‐A phylogenetic tree was analysed by dnaman software. Full‐length nucleotide sequences of 15 HLA‐A alleles (GenBank Accession numbers EU445470 – EU445484 ) were obtained. HLA‐A*110101, A*2301, A*300101, A*310102, A*330301, A*340101, A*680102 and A*6901 alleles were firstly reported for complete genomic sequences. Total 247 polymorphism positions were found in the complete genomic sequences of HLA‐A alleles and a insertion of 17 nucleotides within intron 3 was observed in several allelic groups. According to the phylogenetic tree of the full‐length nucleotide sequences, HLA‐A locus was classified into seven major allelic lineages. In this study, complete genomic sequences of common HLA‐A alleles were obtained and the data will help us understand the evolution of HLA‐A.     

新等位基因HLA-A*24:233与HLA-A*26:89的分析确认

背景：分子生物学新技术的发展和大量应用加快了中国发现HLA 新等位基因的步伐。新等位基因的发现不仅给HLA家族增加了新成员,同时也为研究民族或地区的优势基因或消失基因(不适合客观环境的基因)找到了突破点。 目的：确认2个新的HLA等位基因,并分析其核苷酸序列。 方法：应用PCR-SBT、GSSP测序基因分型技术对两份中华骨髓库供者样本进行HLA高分辨分型,发现2个样本HLA-A位点均为异常基因,与已知同源性最高的等位基因型进行序列比对,分析核苷酸序列的差异。 结果与结论：2个样本HLA-A位点与目前已知的相应HLA-A等位基因序列均不一致,样本1与其同源性最高的A*24:02:01的差异表现在第3外显子区域中的第360位碱基由G > C,导致第96位密码子由谷氨酰胺变为组氨酸,样本2与其同源性最高的A*26:01:01比较差异表现在第2外显子区域中第97位碱基由T>C,导致编码的第9位密码子由酪氨酸变为组氨酸。结果表明两个样本为HLA-A位点的新等位基因,已提交GenBank进行注册,并已被WHO HLA因子命名委员会正式命名为HLA-A*24:233与HLA-A*26:89。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：