376
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Plomp JJ, Molenaar PC, O'Hanlon GM, Jacobs BC, Veitch J, Daha MR, van Doorn PA, van der Meché FG, Vincent A, Morgan BP, Willison HJ. Miller Fisher anti-GQ1b antibodies: alpha-latrotoxin-like effects on motor end plates. Ann Neurol 1999; 45:189-99. [PMID: 9989621 DOI: 10.1002/1531-8249(199902)45:2<189::aid-ana9>3.0.co;2-t] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the Miller Fisher syndrome (MFS) variant of the Guillain-Barré syndrome, weakness is restricted to extraocular muscles and occasionally other craniobulbar muscles. Most MFS patients have serum antibodies against ganglioside type GQ1b of which the pathophysiological relevance is unclear. We examined the in vitro effects of MFS sera, MFS IgG, and a human monoclonal anti-GQ1b IgM antibody on mouse neuromuscular junctions (NMJs). It was found that anti-GQ1b antibodies bind at NMJs where they induce massive quantal release of acetylcholine from nerve terminals and eventually block neuromuscular transmission. This effect closely resembled the effect of the paralytic neurotoxin alpha-latrotoxin at the mouse NMJs, implying possible involvement of alpha-latrotoxin receptors or associated downstream pathways. By using complement-deficient sera, the effect of anti-GQ1b antibodies on NMJs was shown to be entirely dependent on activation of complement components. However, neither classical pathway activation nor the formation of membrane attack complex was required, indicating the effects could be due to involvement of the alternative pathway and intermediate complement cascade products. Our findings strongly suggest that anti-GQ1b antibodies in conjunction with activated complement components are the principal pathophysiological mediators of motor symptoms in MFS and that the NMJ is an important site of their action.
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377
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Hill M, Beeson D, Moss P, Jacobson L, Bond A, Corlett L, Newsom-Davis J, Vincent A, Willcox N. Early-onset myasthenia gravis: a recurring T-cell epitope in the adult-specific acetylcholine receptor epsilon subunit presented by the susceptibility allele HLA-DR52a. Ann Neurol 1999; 45:224-31. [PMID: 9989625 DOI: 10.1002/1531-8249(199902)45:2<224::aid-ana13>3.0.co;2-b] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
No immunodominant T-cell epitopes have yet been reported in the human acetylcholine receptor (AChR), the target of the pathogenic autoantibodies in myasthenia gravis (MG). We have selected and characterized T cells from MG patients by restimulation in culture with recombinant human AChR to alpha, gamma and epsilon subunits; the gamma and epsilon distinguish the fetal and adult AChR isoforms, respectively. We obtained clones specific for the epsilon, rather than the alpha or gamma, subunit in 3 of the first 4 early-onset MG cases tested. They all responded to peptide epsilon201-219 and to low concentrations of adult but not fetal AChR. Moreover, although using different T-cell receptor genes, they were all restricted to HLA-DR52a (DRB3*0101), a member of the strongly predisposing HLA-A1-B8-DR3 haplotype. This apparently immunodominant epsilon201-219 epitope (plus DR52a) was also recognized by clones from an elderly patient whose MG had recently been provoked by the drug D-penicillamine. In all 4 cases, however, the serum antibodies reacted better with fetal than adult AChR and may thus be end products of determinant spreading initiated by adult AChR-specific T cell responses. Furthermore, as these T cells had a pathogenic Th1 phenotype, with the potential to induce complement-activating antibodies, they should be important targets for selective immunotherapy.
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378
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Vincent A, Hart I, Pinto A, Stephenson FA. Antibodies to ion channels. Methods Enzymol 1999; 294:677-704. [PMID: 9916255 DOI: 10.1016/s0076-6879(99)94039-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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379
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Abstract
Antibodies to GM1 ganglioside are found in some patients with the Guillain-Barré syndrome and multifocal motor neuropathy, and may alter neuronal excitability. We measured voltage-gated sodium channel (VGSC) function by 22Na+ influx in a motor neuronal cell line (NSC19) in which we demonstrated GM1 ganglioside and tetrodotoxin-sensitive VGSC function. We were unable to detect any effect of peripheral neuropathy plasmas, with or without complement, on VGSC function in NSC19 cells.
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380
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Alexeev T, Krivoshein A, Shevalier A, Kudelina I, Telyakova O, Vincent A, Utkin Y, Hucho F, Tsetlin V. Physicochemical and immunological studies of the N-terminal domain of the Torpedo acetylcholine receptor alpha-subunit expressed in Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 259:310-9. [PMID: 9914508 DOI: 10.1046/j.1432-1327.1999.00041.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The nicotinic acetylcholine receptor (AChR) from the electric organ of Torpedo species is an oligomeric protein composed of alpha2 beta gamma delta subunits. Although much is known about its tertiary and quaternary structure, the conformation of the large extracellular domains of each of the subunits has not been analysed in detail. In order to obtain information about the spatial structure of the extracellular domain, we have expressed the N-terminal fragment 1-209 of the Torpedo californica AChR alpha-subunit in Escherichia coli. Two vectors coding for a (His)6 tag, either preceding or following the 1-209 sequence, were used and the recombinant proteins obtained (designated alpha1-209pET and alpha1-209pQE, respectively) were purified by affinity chromatography on a Ni2+-agarose column. The chemical structure of both proteins was verified by Edman degradation and mass spectrometry. The proteins were soluble in aqueous buffers but to make possible a comparison with the whole AChR or its isolated subunits, the recombinant proteins were analyzed both in aqueous solution and with the addition of detergents. The two proteins bound [125I]alpha-bungarotoxin with equal potency (KD approximately 130 nm, Bmax approximately 10 nmol.mg-1). Both were shown to interact with several monoclonal antibodies raised against purified Torpedo AChR. The circular dichroism (CD) spectra of the two proteins in aqueous solution revealed predominantly beta-structure (50-56%), the fraction of alpha-helices amounting to 32-35%. Nonionic (beta-octylglucoside) and zwitterionic (CHAPS) detergents did not appreciably change the CD spectra, while the addition of SDS or trifluoroethanol decreased the percentage of beta-structure or increased the alpha-helicity, respectively. The predominance of beta-structure is in accord with recent data on the N-terminal domain of the mouse muscle AChR alpha-subunit expressed in the mammalian cells [West et al. (1997) J. Biol. Chem. 272, 25 468]. Thus, expression in E. coli provides milligram amounts of the protein that retains several structural characteristics of the N-terminal domain of the Torpedo AChR alpha-subunit and appears to share with the latter a similar secondary structure. The expression of recombinant polypeptides representing functional domains of the AChR provides an essential first step towards a more detailed structural analysis.
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381
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Ruez C, Payre F, Vincent A. Transcriptional control of Drosophila bicoid by Serendipity delta: cooperative binding sites, promoter context, and co-evolution. Mech Dev 1998; 78:125-34. [PMID: 9858707 DOI: 10.1016/s0925-4773(98)00159-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Concentration of maternal BICOID (BCD) establishes the anterior pattern in the Drosophila embryo. Successive deletions in the bcd promoter allowed us to localize an enhancer sequence in the 5'-UTR and a down-regulating element downstream of the ATG initiator codon, and identify a 49 bp region sufficient to drive transcription of a reporter gene specifically in nurse cells. This fragment contains two binding sites for the Serendipity (Sry) d zinc finger activator, that mediate its cooperative binding. Both sites (sdbs) are essential for bcd expression. Further analysis showed that the bcd promoter configuration is decisive for Sry d activating function. Replacement of sdbs by binding sites for Sry b, the Sry d paralog, restores bcd transcription in sry d mutant ovaries, demonstrating that the functional divergence between these two proteins during evolution was mainly driven by changes in their DNA-specific recognition properties, resulting in the control of separate developmental pathways.
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382
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383
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Wintzen AR, Plomp JJ, Molenaar PC, van Dijk JG, van Kempen GT, Vos RM, Wokke JH, Vincent A. Acquired slow-channel syndrome: a form of myasthenia gravis with prolonged open time of the acetylcholine receptor channel. Ann Neurol 1998; 44:657-64. [PMID: 9778265 DOI: 10.1002/ana.410440412] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A 32-year-old female presented with a 2-year history of fluctuating generalized weakness including extraocular, bulbar, and limb muscles, suggesting myasthenia gravis, but with poor response to pyridostigmine and unusual electromyographic findings. After rest, power increased on repeated maximal contractions, followed by progressive weakness. There were decremental responses at low-frequency stimulation, but incremental responses at high frequencies, and single stimuli evoked repetitive compound muscle action potentials. Plasmapheresis was ineffective. In a conventional assay, antibodies against acetylcholine receptors (AChRs) were borderline. However, in an assay using cells expressing mainly adult-type human AChRs, the patient's serum was positive. Thymectomy revealed a hyperplastic thymus. An intercostal muscle specimen revealed small miniature end-plate potentials, 0.22+/-0.02 mV instead of 0.56+/-0.05 mV in controls. The number of 125I-alpha-bungarotoxin binding sites was normal. The decay time constant of end-plate potentials was increased from 5.3+/-0.6 msec in controls to 23+/-3.6 msec in the patient. Ultrastructurally, there was no destruction of the end plate. Transfer of the patient's plasma to mice in vivo produced similar physiological changes in their diaphragms. We conclude that the patient has an immune-mediated disorder, in which an antibody specific to the adult form of the AChRs alters the channel properties, reducing total current and slowing the closure. We propose the name "acquired slow-channel syndrome" for this variant of myasthenia gravis.
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384
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Ibnsouda S, Ferrer P, Vincent A. Conservation of read-through transcription of the Drosophila serendipity genes during evolution is gratuitous. MOLECULAR & GENERAL GENETICS : MGG 1998; 259:484-90. [PMID: 9790579 DOI: 10.1007/s004380050839] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Drosophila melanogaster serendipity (sry) genes sry alpha and sry beta, which code for unrelated proteins and functions, are transcribed both as monocistronic (sry alpha, srv beta) and dicistronic (sry beta-sry alpha) polyadenylated transcripts, the three types of transcripts being differentially expressed throughout development. We show here that, while the sry gene cluster is conserved in two other distantly related Drosophila species, sry beta-sry alpha dicistronic transcription is observed in one of them, Drosophila pseudoobscura but not in the other, Drosophila virilis, indicating that this mode of transcription is not subject to selection during evolution. Sequence comparison of the intergenic sry beta-sry alpha region suggests that sry, beta-sry alpha read-through transcription results from interference between initiation of transcription at the sry alpha promoter and 3' processing of the upstream sry beta transcript. From these and previous analyses, we propose that read-through transcription at the sry locus reflects its clustered gene organisation but is functionally gratuitous. This conclusion is supported by the autonomous rate of evolutionary sequence divergence shown by each individual sry gene.
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385
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Curnow J, Corlett L, Nagvekar N, Willcox N, Vincent A. Presentation of endogenous acetylcholine receptor (AChR) by human myoblasts to AChR-specific CD4+ T helper cell clones from myasthenia gravis (MG) patients. J Neuroimmunol 1998. [DOI: 10.1016/s0165-5728(98)91707-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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386
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Moiola L, Galbiati F, Martino G, Amadio S, Brambilla E, Comi G, Vincent A, Grimaldi L, Adorini L. Interleukin 12 is critical in the development of experimental autoimmune myasthenia gravis. J Neuroimmunol 1998. [DOI: 10.1016/s0165-5728(98)91728-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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387
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Bally-Cuif L, Dubois L, Vincent A. Molecular cloning of Zcoe2, the zebrafish homolog of Xenopus Xcoe2 and mouse EBF-2, and its expression during primary neurogenesis. Mech Dev 1998; 77:85-90. [PMID: 9784615 DOI: 10.1016/s0925-4773(98)00144-0] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Xcoe2 is a recently identified HLH transcription factor of the Xenopus primary neurogenesis pathway, which is necessary downstream of Neurogenin to stabilize neuroblast determination (Dubois, L. et al., 1998. Curr. Biol. 8, 199-209). We report here the embryonic expression pattern of Zcoe2, its zebrafish homolog. As observed for Xcoe2, Zcoe2 is strongly expressed in a subset of the neurogenin1- (ngn1-) positive primary neuroblasts of the spinal cord. In the anterior neural plate, in contrast, Zcoe2 is expressed earlier and more widely than ngn1. This pattern is strongly maintained in the presumptive mesencephalon and rhombomeres 1-4 until the 2-3-somite stage. This expression of Zcoe2 in the brain anlage calls for a re-analysis in zebrafish of the functional relationship demonstrated in Xenopus between Coe2 and Neurogenin factors. At later stages, Zcoe2 is expressed in early forming neurons of the anterior brain and is a marker of the olfactory placodes.
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388
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Vincent A. Antiganglioside antibodies in peripheral neuropathies. J Clin Pathol 1998; 51:641-2. [PMID: 9930063 PMCID: PMC500896 DOI: 10.1136/jcp.51.9.641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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389
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Amyes E, Curnow J, Vincent A. IgG subclass of antibodies to Yo in patients with paraneoplastic cerebellar degeneration. J Neuroimmunol 1998. [DOI: 10.1016/s0165-5728(98)91775-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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390
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Plested C, Curnow J, Vincent A. IgM antibodies and phosphorylation of acetylcholine receptors (AChR) in seronegative myasthenia gravis (SNMG). J Neuroimmunol 1998. [DOI: 10.1016/s0165-5728(98)91741-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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391
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Moiola L, Galbiati F, Martino G, Amadio S, Brambilla E, Comi G, Vincent A, Grimaldi LM, Adorini L. IL-12 is involved in the induction of experimental autoimmune myasthenia gravis, an antibody-mediated disease. Eur J Immunol 1998; 28:2487-97. [PMID: 9710226 DOI: 10.1002/(sici)1521-4141(199808)28:08<2487::aid-immu2487>3.0.co;2-y] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
IL-12 has been shown to be involved in the pathogenesis of Th1-mediated autoimmune diseases, but its role in antibody-mediated autoimmune pathologies is still unclear. We investigated the effects of exogenous and endogenous IL-12 in experimental autoimmune myasthenia gravis (EAMG). EAMG is an animal model for myasthenia gravis, a T cell-dependent, autoantibody-mediated disorder of neuromuscular transmission caused by antibodies to the muscle nicotinic acetylcholine receptor (AChR). Administration of IL-12 with Torpedo AChR (ToAChR) to C57BL/6 (B6) mice resulted in increased ToAChR-specific IFN-gamma production and increased anti-ToAChR IgG2a serum antibodies compared with B6 mice primed with ToAChR alone. These changes were associated with earlier and greater neurophysiological evidence of EAMG in the IL-12-treated mice, and reduced numbers of AChR. By contrast, when IL-12-deficient mice were immunized with ToAChR, ToAChR-specific Th1 cells and anti-ToAChR IgG2a serum antibodies were reduced compared to ToAChR-primed normal B6 mice, and the IL-12-deficient mice showed almost no neurophysiological evidence of EAMG and less reduction in AChR. These results indicate an important role of IL-12 in the induction of an antibody-mediated autoimmune disease, suggest that Th1-dependent complement-fixing IgG2a anti-AChR antibodies are involved in the pathogenesis of EAMG, and help to account for the lack of correlation between anti-AChR levels and clinical disease seen in many earlier studies.
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392
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Vincent A, Willcox N, Hill M, Curnow J, MacLennan C, Beeson D. Determinant spreading and immune responses to acetylcholine receptors in myasthenia gravis. Immunol Rev 1998; 164:157-68. [PMID: 9795773 DOI: 10.1111/j.1600-065x.1998.tb01217.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In myasthenia gravis (MG), antibodies to the muscle acetylcholine receptor (AChR) cause muscle weakness. Experimental autoimmune myasthenia gravis (EAMG) can be induced by immunisation against purified AChR; the main immunogenic region (MIR) is a conformation-dependent site that includes alpha 67-76. EAMG can also occur after immunisation against extracellular AChR sequences, but this probably involves intramolecular determinant spreading. In MG patients, thymic hyperplasia and germinal centres are found in about 50%, and thymoma in 10-15%. The heterogeneous, high affinity, IgG anti-AChR antibodies appear to be end-products of germinal centre responses, and react mainly with the MIR or a site on fetal AChR; the latter contains a gamma subunit and is mainly expressed on myoid cells in the thymic medulla. T cells cloned against recombinant AChR subunits recognise principally two naturally processed epitopes: epsilon 201-219 derived from adult AChR which is expressed in muscle, and sometimes in thymic epithelium, and alpha 146-160, common to fetal and adult AChR. Since AChR is not normally co-expressed with class II, it is unclear how CD4+ responses to AChR alpha and epsilon subunits are initiated, and how and where these spread to induce antibodies against fetal AChR. Various possibilities, including upregulation of class II on muscle/myoid cells and involvement of CD8+ responses to AChR and other muscle antigens, are discussed.
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393
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Vincent A. [The nurse in the new health care system of Tchad]. SOINS. PEDIATRIE, PUERICULTURE 1998:18-20. [PMID: 9739322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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394
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Curnow SJ, Willcox N, Vincent A. Induction of primary immune responses by allogeneic human myoblasts: dissection of the cell types required for proliferation, IFNgamma secretion and cytotoxicity. J Neuroimmunol 1998; 86:53-62. [PMID: 9655472 DOI: 10.1016/s0165-5728(98)00013-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Non-professional antigen-presenting cells (APC) have a limited ability to activate T lymphocytes during normal and auto-immune responses. Myoblasts could play an important role as APC in the etiology of autoimmune myasthenia gravis and polymyositis, as well as during muscle graft rejection. We examined the role of different component cell subsets in the response of human peripheral blood mononuclear cells (PBMC) to allogeneic myoblasts. Treatment of myoblasts with TNFalpha or IFNgamma led to the expression of a range of immunostimulatory molecules including MHC class I and II, and CD95 (Fas), but not B7 family molecules. Whole PBMC, cultured with allogeneic myoblasts, proliferated, secreted IFNgamma, and were cytotoxic. Proliferation and IFNgamma secretion were largely dependent on the presence of CD4+ lymphocytes, but neither CD4+ nor CD8+ T cells were responsible for cytotoxicity, which was mediated by MHC class II+ non-T mononuclear cells. However, purified CD4+ lymphocytes co-cultured with allogeneic myoblasts required co-stimulation with anti-CD28 antibodies for proliferation and IFNgamma secretion, which only induced a low level of IFNgamma secretion by CD8+ lymphocytes and did not induce cytotoxic function. These results suggest that human myoblasts can act as antigen-presenting cells for naive T lymphocytes, but only with additional co-stimulation.
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395
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Rothschild MF, Messer LA, Vincent A. Molecular approaches to improved pig fertility. JOURNAL OF REPRODUCTION AND FERTILITY. SUPPLEMENT 1998; 52:227-36. [PMID: 9602731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Geneticists have made limited progress in improving reproductive traits in pigs through traditional selection and crossbreeding systems. Recent advances in molecular genetics and the human genome project have allowed progress in gene identification and gene mapping in pigs. The pig genetic linkage map now has over 1700 genetic markers, and about 200 of these are genes. Furthermore, comparative genomic maps are improving and are becoming useful tools. Molecular approaches such as candidate gene identification and genomic scans permit new genes and chromosomal regions to be discovered which may influence reproduction. One significant finding is that the oestrogen receptor locus (ESR) is associated with increased litter size. Differences between female Chinese pig ESR BB and AA homozygotes have averaged 2.3 pigs born alive for first parity, and in commercial Large White crosses the differences are about 0.9 pigs per litter. Additional new genes have been discovered which may significantly affect litter size. Initial genome scans have revealed that there may be a gene or genes influencing ovulation rate and litter size on chromosome 8. Approaches such as positional comparative candidate gene analysis and eventually positional cloning will probably identify the genes controlling reproduction in pigs.
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396
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Nagvekar N, Moody AM, Moss P, Roxanis I, Curnow J, Beeson D, Pantic N, Newsom-Davis J, Vincent A, Willcox N. A pathogenetic role for the thymoma in myasthenia gravis. Autosensitization of IL-4- producing T cell clones recognizing extracellular acetylcholine receptor epitopes presented by minority class II isotypes. J Clin Invest 1998; 101:2268-77. [PMID: 9593783 PMCID: PMC508815 DOI: 10.1172/jci2068] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Myasthenia gravis (MG) is caused by helper T cell-dependent autoantibodies against the muscle acetylcholine receptor (AChR). Thymic epithelial tumors (thymomas) occur in 10% of MG patients, but their autoimmunizing potential is unclear. They express mRNAs encoding AChR alpha and epsilon subunits, and might aberrantly select or sensitize developing thymocytes or recirculating peripheral T cells against AChR epitopes. Alternatively, there could be defective self-tolerance induction in the abundant maturing thymocytes that they usually generate. For the first time, we have isolated and characterized AChR-specific T cell clones from two MG thymomas. They recognize extracellular epitopes (alpha75-90 and alpha149-158) which are processed very efficiently from muscle AChR. Both clones express CD4 and CD8alpha, and have a Th-0 cytokine profile, producing IL-4 as well as IFN-gamma. They are restricted to HLA-DP14 and DR52a; expression of these minority isotypes was strong on professional antigen-presenting cells in the donors' tumors, although it is generally weak in the periphery. The two clones' T cell receptor beta chains are different, but their alpha chain sequences are very similar. These resemblances, and the striking contrasts with T cells previously cloned from non-thymoma patients, show that thymomas generate and actively induce specific T cells rather than merely failing to tolerize them against self antigens.
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397
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Polizzi A, Lang B, Amyes E, Newsom-Davis J, Vincent A. Neuronal staining patterns in sera from patients with Lambert-Eaton myasthenic syndrome. Ann N Y Acad Sci 1998; 841:684-6. [PMID: 9668314 DOI: 10.1111/j.1749-6632.1998.tb11002.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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398
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Buckel A, James E, Jacobson L, Biewenga J, Beeson D, Vincent A. Evidence for an association between human acetylcholine receptor and rapsyn. Ann N Y Acad Sci 1998; 841:14-6. [PMID: 9668218 DOI: 10.1111/j.1749-6632.1998.tb10906.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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399
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Croxen R, Beeson D, Newland C, Betty M, Vincent A, Newsom-Davis J. A single nucleotide deletion in the epsilon subunit of the acetylcholine receptor (AChR) in five congenital myasthenic syndrome patients with AChR deficiency. Ann N Y Acad Sci 1998; 841:195-8. [PMID: 9668239 DOI: 10.1111/j.1749-6632.1998.tb10927.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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400
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MacLennan CA, Beeson D, Willcox N, Vincent A, Newsom-Davis J. Muscle nicotinic acetylcholine receptor mRNA expression in hyperplastic and neoplastic myasthenia gravis thymus. Ann N Y Acad Sci 1998; 841:407-10. [PMID: 9668266 DOI: 10.1111/j.1749-6632.1998.tb10954.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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