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Biomedical subjects

J I Bell

Publications and source records attributed to J I Bell.

At least 91 records · Page 5Linked to original sources
PubMed1993

Conservation of T cell receptor usage by HLA B27-restricted influenza-specific cytotoxic T lymphocytes suggests a general pattern for antigen-specific major histocompatibility complex class I-restricted responses.

Eight HLA B27-restricted influenza A virus nucleoprotein 383-391-specific cytotoxic T lymphocyte (CTL) clones were obtained from three unrelated donors following natural infection. T cell receptor (TcR) usage was studied using the "anchored" polymerase chain reaction. TcR alpha-chain usage was restricted with three predominant V alpha (V alpha 12.1, 14.1, 22) and two predominant J alpha segments. beta-chain variable-region usage was also conserved, with V beta 7 being used by five clones despite contributing less than 2% of peripheral blood lymphocyte V beta sequences of one individual studied. The TcR beta-chain junctional region was highly conserved even between CTL clones from unrelated individuals, with a negatively charged amino acid, contributed to by N-region addition, encoded at position 97 in all but two clones. This study shows that peptide-specific HLA B27-restricted CTL following influenza virus infection use very similar TcR and, when considered with previous studies, suggests a pattern of TcR conservation for major histocompatibility complex class I-restricted responses. No difference in TcR usage was detected between one healthy donor and two with HLA B27-associated arthritis.

Amino Acid Sequence↗
PubMed1993

TAP1 and TAP2 polymorphism in coeliac disease.

Coeliac disease is strongly associated with HLA-DQ2, but it is possible that additional major histocompatibility complex genes also confer disease susceptibility. Encoded close to HLA-DQ are two genes, TAP1 and TAP2, whose products are believed to transport antigenic peptides from the cytoplasm into the endoplasmic reticulum. Comparison of 81 coeliac disease patients with caucasoid controls revealed an increased frequency of the alleles TAP1A and TAP2A in the patient population. However, no significant difference was found when patients were compared with HLA-DR and -DQ matched controls, indicating linkage disequilibrium between TAP1A, TAP2A, and HLA-DQ2. The TAP gene products do not have a major influence on susceptibility or resistance to coeliac disease in a Northern European Caucasoid population.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Polygenic disease.

Considerable success is now being achieved in defining genetic susceptibility loci in polygenic disease. In particular, new susceptibility loci have been identified in hypertension, type I and type II diabetes, asthma and malaria infection. The approaches and tools for mapping such susceptibility determinants are becoming more clearly defined and the identification of further susceptibility genes is likely to be in demand in the near future.

Animals↗
PubMed1993

Susceptibility to insulin dependent diabetes mellitus maps to a 4.1 kb segment of DNA spanning the insulin gene and associated VNTR.

Recent studies have demonstrated that a locus at 11p15.5 confers susceptibility to insulin dependent diabetes mellitus (IDDM). This locus has been shown to lie within a 19 kb region. We present a detailed sequence comparison of the predominant haplotypes found in this region in a population of French Caucasian IDDM patients and controls. Identification of polymorphisms both associated and unassociated with IDDM has allowed us to define further the region of association to 4.1 kb. Ten polymorphisms within this region are in strong linkage disequilibrium with each other and extend across the insulin gene locus and the variable number tandem repeat (VNTR) situated immediately 5' to the insulin gene. These represent a set of candidate disease polymorphisms one or more of which may account for the susceptibility to IDDM.

Base Sequence↗
PubMed1993

The association of HLA DR beta alleles with self-limiting and persistent forms of early symmetrical polyarthritis.

RA is associated with a group of class II DR beta alleles, which share a conserved sequence in the third allelic hypervariable region (3AHVR). These include the DR4 subtypes Dw4, Dw14 and Dw15, and also DR1. In contrast Dw10 and Dw13 which are also DR4 subtypes show no association with RA and have a quite distinct 3AHVR. We have assessed the frequency of these alleles in 55 patients who initially presented with symmetrical peripheral polyarthritis suggestive of RA. After 4 years 27 had progressed to definite or classical RA, while 28 had never fulfilled the criteria for this disease. Dw4 was markedly elevated in the rheumatoid group (17/23) compared with either the non-rheumatoids (5/28) or healthy controls (12/100). Dw14 and non-DR4 associated DR1 were not elevated in either group of patients. This study suggests that the DR beta association with RA is likely to facilitate persistence or severity of disease rather than the initial induction of symmetrical peripheral arthritis.

Adult↗
PubMed1993

Rapid HLA typing by multiplex amplification refractory mutation system.

AIMS: To detect HLA susceptibility and protective alleles associated with insulin dependent diabetes mellitus (IDDM) using a multiplex amplification refractory mutation system (ARMS). These include DR3 and DR4 alleles at the DRB1 locus, presence or absence of aspartic acid at position 57 (Asp-57) of the DQB1 locus, and presence or absence of arginine at position 52 (Arg-52) of the DQA1 locus. METHODS: The ARMS approach was used to design allele specific primers for the detection of the major susceptibility and protective alleles for IDDM. These include DR3 and DR4 alleles at the DRB1 locus, Asp-57 and non-Asp-57 at the DQB1 locus, and Arg-52 and non-Arg-52 alleles at the DQA1 locus. The allele specificity of each set of primers was first tested separately using DNA samples from 15 individuals previously typed for the DRB1, DQB1, and DQA1 loci using the sequence specific oligonucleotide (SSO) technique. The possibility of using multiplex ARMS for typing multiple susceptibility/protective alleles for IDDM was further investigated by testing various combinations of allele specific primers, thereby reducing the number of separate polymerase chain reactions required to type all these alleles. RESULTS: A "three-tube" system worked well and gave accurate results. Tube 1 contained ARMS primers for the detection of IDDM susceptibility alleles DR3 and DR4; tube 2 contained ARMS primers for the detection of susceptibility alleles non-Asp-57 and Arg-52; and tube 3 contained ARMS primers for the detection of the protective alleles Asp-57 and non-Arg-52. DNA samples typed with this ARMS method were in complete agreement with those obtained using the SSO technique. CONCLUSION: This method is rapid and has no requirement for radioactivity. It is an efficient method for population screening.

Alleles↗
PubMed1992

Genomic structure of DNA encoding the lymphocyte homing receptor CD44 reveals at least 12 alternatively spliced exons.

The CD44 molecule is known to display extensive size heterogeneity, which has been attributed both to alternative splicing and to differential glycosylation within the extracellular domain. Although the presence of several alternative exons has been partly inferred from cDNA sequencing, the precise intron-exon organization of the CD44 gene has not been described to date to our knowledge. In the present study we describe the structure of the human CD44 gene, which contains at least 19 exons spanning some 50 kilobases of DNA. We have identified 10 alternatively spliced exons within the extracellular domain, including 1 exon that has not been previously reported. In addition to the inclusion or exclusion of whole exons, more diversity is generated through the utilization of internal splice donor and acceptor sites within 2 of the individual exons. The variation previously reported for the cytoplasmic domain is shown to result from the alternative splicing of 2 exons. The genomic structure of CD44 reveals a remarkable degree of complexity, and we confirm the role of alternative splicing as the basis of the structural and functional diversity seen in the CD44 molecule.

Alternative Splicing↗
PubMed1992

Clostridium perfringens enterotoxin is a superantigen reactive with human T cell receptors V beta 6.9 and V beta 22.

Candidate superantigens were screened for their ability to induce lysis of human histocompatibility leukocyte antigen class II-positive targets by human CD8+ influenza-specific cytotoxic T cell (CTL) lines. Clostridium perfringens enterotoxin (CPET) induced major histocompatibility complex unrestricted killing by some but not all CTL lines. Using "anchored" polymerase chain reactions, CPET was shown to selectively stimulate peripheral blood lymphocytes bearing T cell receptor V beta 6.9 and V beta 22 in five healthy donors. V beta 24, V beta 21, V beta 18, V beta 5, and V beta 6.1-5 appeared to be weakly stimulated. Antigen processing was not required for CPET to induce proliferation. Like the staphylococcal enterotoxins, CPET is a major cause of food poisoning. These data suggest that superantigenic and enterotoxigenic properties may be closely linked.

Antigens, Bacterial↗
PubMed1992

Analysis of complex genetic systems by ARMS-SSCP: application to HLA genotyping.

We have developed a new method for analysis of complex genetic systems by a combination of the Amplification Refractory Mutation System (ARMS) and Single-Strand Conformation Polymorphism (SSCP) analysis: ARMS-SSCP. Thus, a complex allelic series is subdivided into a number of groups by ARMS followed by the identification of specific alleles using SSCP analysis. We have shown that the HLA alleles at the DRB3 and DQB1 loci were distinguishable from each other using ARMS-SSCP. In 36 individuals typed for the DRB3 and 48 individuals typed for the DQB1 loci, ARMS-SSCP results were in complete agreement with those obtained using the established method of sequence-specific oligonucleotide (SSO) hybridisation. With silver staining, ARMS-SSCP is a rapid, non-radioactive and reliable method which also offers the possibility for detecting new HLA alleles. We have demonstrated that ARMS-SSCP can be performed using fluorescent PCR primers, a feature which gives the method potential for automation.

Base Sequence↗
PubMed1992

Multiple variants of the human lymphocyte homing receptor CD44 generated by insertions at a single site in the extracellular domain.

The human CD44 cell-surface glycoprotein participates in a wide variety of cell-cell interactions including lymphocyte homing and tumor metastasis. The CD44 antigen is known to display extensive size heterogeneity when compared between different tissue sources although the structural basis for this variation is not yet clear. Recently, two further isotypes in addition to the basic hemopoietic form of the CD44 antigen have been cloned and sequenced and these have been found to contain all or part of a 200-400-base pair insert within the extracellular domain, suggesting that the characteristic heterogeneity in the molecule may be generated by a mechanism of alternative splicing. We have obtained further evidence for alternative splicing, and we report here the cloning and sequencing of six different CD44 sequence variants from a variety of cell lines using a combination of expression cloning and the polymerase chain reaction. Comparison of these variants indicates that each is probably assembled by the insertion of five different exon units in tandem into a discrete site within the membrane proximal region of the extracellular domain. One of the variants contains an exon that shares extensive amino acid sequence homology with a recently described rat CD44 variant that mediates tumor metastasis. Another variant contains a new exon that encodes a tandem repeat of the consensus sequence SG for covalent modification with chondroitin sulfate and is expressed predominantly on mammary tumors. We suggest that a mechanism of alternative exon splicing generates much of the observed structural heterogeneity of CD44 and that the particular set of CD44 variants expressed in a single cell may represent a precise postal code directing the final destination of migrating cells and metastatic tumors.

Amino Acid Sequence↗
PubMed1992

Variation in human T cell receptor V beta and J beta repertoire: analysis using anchor polymerase chain reaction.

Anchor polymerase chain reaction has been applied to the study of human T cell receptor beta chain repertoire in peripheral blood. The use of this technique has demonstrated that considerable variation in V beta and J beta usage exists, both within and between individuals. Particular V beta families, including V beta 6, V beta 4 and V beta 12 are commonly utilized, while families such as V beta 10, V beta 11 and V beta 15 are rare in all individuals studied. Marked interindividual variation in V beta usage was detected for V beta 12 and V beta 4. Biased usage of J beta elements is a prominent feature of peripheral repertoire, while there is no evidence for preferential V beta-J beta recombination events. Biased J beta usage in expressed V beta-D beta-J beta-C beta transcripts, subject to selection, was the same as that in aberrant, unselected D beta-J beta-C beta transcripts, implying that bias resulted from events relating to rearrangement itself, in the absence of selection. N-region diversity showed some evidence for preferential insertion of deoxyguanosine, consistent with the action of terminal deoxytransferase. No P-nucleotide incorporation was seen in association with intact J beta elements. These data provide evidence of some of the variation in human T cell receptor beta chain repertoire and provide a basis for comparisons with sequences which may be obtained in autoimmune and superantigen-mediated diseases.

Amino Acid Sequence↗
PubMed1992

Molecular cloning of a novel member of the immunoglobulin gene superfamily homologous to the polymeric immunoglobulin receptor.

The CMRF35 monoclonal antibody recognizes a cell membrane antigen present on the surface of monocytes, neutrophils, a proportion of peripheral blood T and B lymphocytes and lymphocytic cell lines. Initial studies with CMRF35 suggested an unusual pattern of serological reactivity which did not correspond to any of the known leukocyte differentiation antigen clusters. We describe here the cloning and sequencing of a cDNA encoding the CMRF35 antigen by means of expression in COS cells and immunoselection with the CMRF35 monoclonal antibody. The cDNA encodes a novel integral membrane glycoprotein of 224 amino acids that represents a new member of the immunoglobulin (Ig) gene superfamily. The molecule comprises (a) a single extracellular Ig variable domain remarkably similar to the Fc receptor for polymeric IgA and IgM, (b) a membrane-proximal domain containing a high proportion of proline, serine and threonine residues that was predicted to be heavily O-glycosylated, (c) an unusual transmembrane anchor that contained a glutamic acid and a proline residue and (d) a short cytoplasmic tail. Transcripts encoding the CMRF35 protein were detected in early monocytic cell lines, in peripheral blood T cells and in some B lymphoblastoid cell lines, confirming the results of immunocytological staining. However, the level of CMRF35 expression on peripheral blood T cells was shown to decrease in response to mitogenic stimulation. The likelihood that the CMRF35 antigen shares a common evolutionary ancestor with the poly Ig Fc receptor is discussed.

Amino Acid Sequence↗
PubMed1992

Isolated HLA-DP mismatches between donors and recipients do not influence the function or outcome of renal transplants.

The matching of donors and renal graft recipients for human leukocyte antigens A, B, and DR has been shown to exert beneficial effects on the outcome of transplantation. Until the advent of polymerase chain reaction amplification-based genotyping, the effect of HLA-DP compatibility on graft survival could not be thoroughly investigated. HLA-DP compatibility has been determined in three living-related transplants and 34 cadaveric transplants for donor-recipient pairs matched for HLA-DR and -DQ. The effect of DP mismatching on graft survival and function was assessed. No clear benefit from matching donor and recipient for HLA-DP could be discerned.

Base Sequence↗
PubMed1992

Missense glucokinase mutation in maturity-onset diabetes of the young and mutation screening in late-onset diabetes.

We describe a codon 299 mutation in the glucokinase gene in a British pedigree with maturity-onset diabetes of the young (MODY) resulting in a substitution of glycine to arginine. One out of fifty patients diagnosed with classical late-onset type 2 diabetes mellitus was also found to have this mutation. All nine relatives of this patient who have inherited the mutation have type 2 diabetes, although six others without the mutation are also present with diabetes. The discovery that glucokinase mutations can cause MODY and was also found in ten affected members of a pedigree with type 2 diabetes in which MODY had not previously been considered indicates that diagnosis based on molecular pathology will be helpful in understanding the aetiology of type 2 diabetes.

Adolescent↗