Wiley

Abstract: Multiple sclerosis (MS) has, since the 1970s, been known to be associated with the HLA‐Dw2 and ‐DR2 specificities in Caucasian Europeans and North Americans. By the use of genomic typing techniques, the association has been specified to be with the DRwlS,DQw6,Dw2, i.e. the DRBI* 1501‐DQAI*0102‐DQBl*0602 haplotype. A significant DPw4 association in Scandinavian MS patients has been described in one report. However, this association has not been confirmed in several subsequent studies with patients from the same and other ethnic groups. During the last few years several reports, based on serological, RFLP and PCR‐SSO data, have suggested that the HLA class II‐associated MS susceptibility gene(s) may be more closely associated with the DQ than with the DR subregion. The observations that the HLA‐DQBI genes of MS patients share long stretches of sequence motifs and also carry DQA1 alleles encoding glutamine at position 34 of the DQ α chain have received considerable attention. It has been suggested that the susceptibility to develop MS might be determined by the corresponding DQ α‐β heterodimers either encoded in cis or in trans. We have investigated these issues in a large group of Swedish MS patients (n= 179). We found that the associations with the suggested DQBI sequences and position 34 of the DQ α chain were due to linkage disequilibrium and secondary to the association with the DRw15,DQw6,Dw2 haplotype (p < 10‐⁹ and p < 10‐⁸, respectively). No overrepresentation of the implicated DQ α‐β heterodimers was observed in DRw1S,DQw6,Dw2‐negative patients. We conclude that available data does not allow the localization of the HLA class II‐associated MS susceptibility genes within the DRw15,DQw6,I>w2 haplotype. We have previously described immunogenetic differences between different clinical forms of MS. In the present study of a new group of MS patients compared with a new control panel, these differences were partly confirmed. The DRw17,DQw2 association in relapsing/remitting MS was affirmed. However, in patients with primarily chronic progressive MS a negative association with the DQw7 allele was not substantiated and a positive association with the DR4.DQw8 haplotype could neither be confirmed nor rejected.

Abstract:  The human major histocompatibility (MHC) genomic region at chromosomal position 6p21 encodes the six classical transplantation HLA genes and many other genes that have important roles in the regulation of the immune system as well as in some fundamental cellular processes. This small segment of the human genome has been associated with more than 100 diseases, including common diseases – such as diabetes, rheumatoid arthritis, psoriasis, asthma and various autoimmune disorders. The MHC 3.6 Mb genomic sequence was first reported in 1999 with the annotation of 224 gene loci. The locus and allelic information of the MHC continue to be updated by identifying newly mapped expressed genes and pseudogenes based on comparative genomics, SNP analysis and cDNA projects. Since 1999, new innovations in bioinformatics and gene‐specific functional databases and studies on the MHC genes have resulted in numerous changes to gene names and better ways to update and link the MHC gene symbols, names and sequences together with function, variation and disease associations. In this study, we present a brief overview of the MHC genomic structure and the recent information that we have gathered on the MHC gene loci via LocusLink at the National Centre for Biological Information (http://www.ncbi.nih.gov/.) and the MHC genes' association with various diseases taken from publications and records in public databases, such as the Online Mendelian Inheritance in Man and the Genetic Association Database.

This paper describes a new cell isolation and HLA typing technique, which permits cell separation and HLA class I or class II typing to be performed in 70 min. Magnetic monodisperse microspheres (Dynabeads TM) were coated with monoclonal antibodies (MAbs) specific for the CD8 T cell antigen or for HLA class II monomorphic epitopes. They could then be used to obtain HLA class I or class II positive cells directly from ACD blood in approximately 15 min by the use of magnetic separation. The cells (attached to the microspheres) were subsequently used in microcytotoxic HLA typing (total incubation time of 55 min) using acridin orange/ethidiumbromide to stain viable (yellow) and dead (red) cells. It was found that this immunomagnetic (IM) HLA typing technique was specific, has a sensitivity superior to that observed for conventional microcytotoxicity assays and gave low background staining. IM HLA‐ABC typing of 50 healthy donors and 10 patients and IM HLA‐DR typing of 25 healthy donors and 30 patients gave results corresponding well with that obtained independently by conventional HLA typing (concordancy rates 92–100%). Furthermore, the IM HLA typing technique permitted reliable HLA class II typing of blood cells from six patients where conventional HLA class II typing was impossible. The IM HLA typing technique also enables HLA class I and II typing to be quickly and reliably performed on cells from ACD blood of cadaveric donors.

We have updated the catalogue of common and well‐documented (CWD) human leukocyte antigen (HLA) alleles to reflect current understanding of the prevalence of specific allele sequences. The original CWD catalogue designated 721 alleles at the HLA‐A, ‐B, ‐C, ‐DRB1, ‐DRB3/4/5, ‐DQA1, ‐DQB1, and ‐DPB1 loci in IMGT (IMmunoGeneTics)/HLA Database release 2.15.0 as being CWD. The updated CWD catalogue designates 1122 alleles at the HLA‐A, ‐B, ‐C, ‐DRB1, ‐DRB3/4/5, ‐DQA1, ‐DQB1, ‐DPA1 and ‐DPB1 loci as being CWD, and represents 14.3% of the HLA alleles in IMGT/HLA Database release 3.9.0. In particular, we identified 415 of these alleles as being ‘common’ (having known frequencies) and 707 as being ‘well‐documented’ on the basis of ~140,000 sequence‐based typing observations and available HLA haplotype data. Using these allele prevalence data, we have also assigned CWD status to specific G and P designations. We identified 147/151 G groups and 290/415 P groups as being CWD. The CWD catalogue will be updated on a regular basis moving forward, and will incorporate changes to the IMGT/HLA Database as well as empirical data from the histocompatibility and immunogenetics community. This version 2.0.0 of the CWD catalogue is available online at cwd.immunogenomics.org, and will be integrated into the Allele Frequencies Net Database, the IMGT/HLA Database and National Marrow Donor Program's bioinformatics web pages.

Aging is associated clinically with increases in the frequency and severity of infectious diseases and an increased incidence of cancer, chronic inflammatory disorders and autoimmunity. These age‐associated immune dysfunctions are the consequence of declines in both the generation of new naïve T and B lymphocytes and the functional competence of memory populations. These alterations collectively are termed immunosenescence.

Abstract: The HLA class II genotypes were determined in the B‐lymphoblastoid cell lines selected for the Tenth International Histocompatibility Workshop. The HLA class II genes were determined by the PCR‐SSOP method using the reagents provided by the Eleventh Histocompatibility Workshop. Additional studies have been performed for further characterization of HLA class II polymorphism on these cell lines. It is observed that several cell lines have HLA class II haplotypes with the same DRB1, DQA1 and DQB1 alleles on both haplotypes but different alleles at the other class II loci, confirming that these cell lines are not truly HLA class II‐homozygous. Other cell lines carried HLA class II haplotypes which were only different at the DRB1 gene. These results suggest double recombination events or gene conversion‐like events in generation of HLA DR, DQ haplotypes. These cell lines provide an important tool as references for HLA DNA typing.

The HLA‐associated susceptibility to develop celiac disease (CD) seems mainly to be conferred by a particular HLA‐DQ heterodimer encoded by the DQA1*0501 and DQB1*0201 genes either in cis or in trans position. To study the possible influence of DRB1 or other DQA1 and DQB1 alleles on the CD susceptibility conferred by these DQ genes, we performed genomic HLA typing of 94 CD patients, selected those who carried at least one copy of the DRB1*0301‐DQA1*0501‐DQB1*0201 haplotype (N = 89) and compared them to 47 random, healthy Norwegians matched with the patients to carry at least one copy of the above haplotype. We found an excess of DQB1*0201 homozygosity in the patients. This was due to an increased frequency of the DRB1*0301‐DQA1*0501‐DQB1*0201 and DRB1*0701‐DQA1*0201‐DQB1*0201 haplotypes present on the other chromosome. We propose that, in individuals carrying the DQA1*0501 and DQB1*0201 alleles, the presence of a second copy of the DQB1*0201 allele increases susceptibility to CD.

Abstract: The characteristics of canine homologues of CD4 and CD8, defined by murine monoclonal antibodies CA13.1E4 (IgG1) and CA9.JD3 (IgG2a) respectively, are described. These antibodies identify mutually exclusive subpopulations of non‐B lymphocytes in peripheral lymphoid organs and blood. However, in thymus the antibodies defined populations of double‐positive, double‐negative and single‐positive cells that showed a progressive maturation consistent with that described for CD4 and CD8 in other mammalian species. Furthermore, functional studies clearly associated cytotoxic effector cell function with the subpopulation reactive with CA9.JD3 (CD8). In contrast, proliferation stimulated by allogeneic cells and mitogens was more pronounced in the subpopulation reactive with CA13.1E4 (CD4). Cell and tissue distribution studies revealed that CA13.1E4 stained neutrophils with equivalent intensity to the staining of peripheral T cells. CA13.1E4 precipitated a 60 kD protein from the surface of T cells and highly purified neutrophils under both reducing and non‐reducing conditions. CA9.JD3 precipitated a heterodimer of 32 kd and 36 kD under reducing conditions, and a 70 kD protein under non‐reducing conditions. The expression of CD4 by canine neutrophils is without precedent in other mammalian species; the functional significance of neutrophil CD4 expression is puzzling in light of the current understanding of the functions of CD4 which include it's role as a receptor for non‐polymorphic regions of MHC class II molecules.

Abstract:  The difference in sizes of conserved stretches of DNA sequence within the major histocompatibility complex (MHC) in human individuals constitutes an underappreciated genetic diversity that has many practical implications. We developed a model to describe the variable sizes of stretches of conserved DNA in the MHC using the known frequencies of four different kinds of small (< 0.2 Mb) blocks of relatively conserved DNA sequence: HLA‐Cw/B; TNF; complotype; and HLA‐DR/DQ. Each of these small blocks is composed of two or more alleles of closely linked loci inherited as one genetic unit. We updated the concept of the conserved extended haplotype (CEH) using HLA allele identification and TNF microsatellites to show that specific combinations of the four blocks form single genetic units (≥ 1.5 Mb) with a total haplotype frequency in the Caucasian population of 0.30. Some CEHs extend to the HLA‐A and ‐DPB1 loci forming fixed genetic units of up to at least 3.2 Mb of DNA. Finally, intermediate fragments of CEHs also exist, which are, nevertheless, larger than any of the four small blocks. This complexity of genetic fixity at various levels should be taken into account in studies of genetic disease association, immune response control, and human diversity. This knowledge could also be used for matching CEHs and their fragments for patients undergoing allotransplantation.