A K Lefvert

Shanghai University of Traditional Chinese Medicine, Shanghai, Shanghai Shi, China

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Publications (172)732.73 Total impact

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    ABSTRACT: Dendritic cells (DCs) initiate immune responses through their direct interaction with effector cells. However, the mechanism by which DC activity is regulated is not well defined. Previous studies have shown that CTLA4 on T cells regulates DCs function by "cross-talk". We investigated whether there is an intrinsic regulatory mechanism in DCs, with CTLA4 as a candidate regulator. We confirmed via RT-PCR and flow cytometry the natural expression of CTLA4 on mature DCs derived from human monocytes. Approximately 8% CD1a-positive cells express CTLA4 both on surface and intracellular, whereas 10% CD1a-negative cells express CTLA4 intracellularly, but little expression was observed on the cell surface. The cross-linking of CTLA4 inhibits DCs maturation and antigen presentation in vitro, but does not inhibit endocytosis. CTLA4 is expressed by DCs and plays an inhibitory role. CTLA4-expressing DCs may represent a group of regulatory DCs. Because of its wide distribution on different cell types, CTLA4 may play a general role in regulating immune responses.
    BMC Immunology 03/2011; 12:21. · 2.61 Impact Factor
  • Acta Neurologica Scandinavica 01/2009; 69:214-215. · 2.47 Impact Factor
  • A.-C. Sundewall, A. K. Lefvert, R. Olsson
    Acta Neurologica Scandinavica 01/2009; 69:202-203. · 2.47 Impact Factor
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    ABSTRACT: To measure clinical and immunological parameters in a patient with myasthenia gravis (MG) treated with antibodies against CD25 (basiliximab, Simulect). Patient and methods - Injections of basiliximab were given repeatedly together with cyclosporin A and corticosteroids for 9 months to a patient with severe MG. Her muscle function score was monitored and the immunological parameters were followed using ELISA, flow cytometry and radioimmunoassay. The patient improved moderately and corticosteroid treatment could be withdrawn. The percentage of activated CD4+ T cells decreased during treatment, while that of 'naïve' T cells increased. The serum levels of sCD28, sCD152, sCD80, sCD86 and IL-10 decreased. The treatment was stopped due to repeated infections. Treatment with basiliximab appears to be suitable only for severely ill patients who do not respond to conventional treatments. However, careful monitoring of side effects is necessary.
    Acta Neurologica Scandinavica 04/2008; 117(3):211-6. · 2.47 Impact Factor
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    ABSTRACT: The molecular mechanisms underlying the regulation of the CD152 (CTLA-4) gene are largely unknown. Two single nucleotide polymorphisms (SNPs) located in the promoter region are suspected to contribute to the pathogenesis of myasthenia gravis (MG) through regulation of gene expression. SETTING, SUBJECTS AND DESIGN: One hundred and sixty-five unrelated Swedish-Caucasian patients with MG (103 females and 62 males, age 17 to 92 years) and 148 ethnically matched healthy individuals were studied. Gene typing of two SNPs (T/C(-1772) and A/G(-1661)) and quantification of soluble CD152 were performed in the patients. Besides the association studies, the function of these two SNPs is characterized. We present new genetic associations of two SNPs in the CD152 gene with human MG. These SNPs located in the promoter region are involved in transcriptional binding activity for Nuclear Factor I (NF-1) and c/EBPbeta, as demonstrated using chromatin immunoprecipitation and electromobility shift assay. MG patients with the T/C(-1772) polymorphism have elevated levels of sCD152 in sera. The two SNPs in the promoter region are associated with MG and might cause abnormal alternative splicing and affect the expression of CD152, thereby contributing to the pathogenesis of MG.
    Journal of Internal Medicine 02/2008; 263(1):61-9. · 6.46 Impact Factor
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    ABSTRACT: CD80 is a costimulatory factor mainly expressed on the surface of activated monocytes, B cells and dendritic cells. In this study, we demonstrate that 24% of healthy individuals have soluble forms of CD80, sCD80, in their serum. The concentration of sCD80 ranged from 0 to 1 mg/l. At the mRNA level, we detected a spliced form s1CD80 (771 bp), in unstimulated monocytes and B cells, while another form named s2CD80 (489 bp) was expressed in activated T cells as well as in freshly isolated and activated monocytes. s1CD80 lacks the transmembrane domain, and the IgC-like domain plus the transmembrane domain are spliced out of s2CD80. We also present data demonstrating that recombinant s1CD80 binds to recombinant CD152-Ig and CD28-Ig. It can also bind to T cells, preferentially to activated T cells. Recombinant sCD80 had immunomodulatory effects shown by its inhibition of the mixed lymphocyte reaction and inhibition of T-cell proliferation. sCD80 in human serum adds a new member to the family of soluble receptors, implying a network of soluble costimulatory factors with functional relevance. The inhibitory effect of the recombinant protein on T-cell activation makes it a possible candidate for treatment of diseases associated with hyperactivated T cells.
    Scandinavian Journal of Immunology 12/2007; 66(5):529-37. · 2.20 Impact Factor
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    ABSTRACT: To measure clinical and immunological parameters in a patient with myasthenia gravis (MG) treated with antibodies against tumour necrosis factor-alpha (infliximab, Remicade). A patient with severe MG received repeated injections of infliximab. His muscle function score was monitored and the immunological parameters were followed using enzyme-linked immunosorbent assay, flow cytometry and radioimmunoassay. The patient improved in muscle fatigability tests and the levels of antibodies against the acetylcholine receptor decreased during treatment. The activation marker human leucocyte antigen-DR on CD4(+) T cells also decreased. Treatment with infliximab might be beneficial for patients with severe MG but demands careful monitoring of possible serious side-effects.
    Acta Neurologica Scandinavica 05/2007; 115(4):279-83. · 2.47 Impact Factor
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    ABSTRACT: The T cell co-stimulatory factors CD28 and CTLA-4 and their ligands CD80 and CD86 occur as receptors on T cells and antigen-presenting cells and also in soluble forms in the circulation. We determined the levels of soluble co-stimulatory molecules in patients with abdominal aortic aneurysm (AAA) and normal individuals. We further correlated these soluble co-stimulatory molecules to other clinical parameters of importance such as age of the patient, presence of hypertension, size of the aneurysm and levels of matrix metalloproteinases-9 and C-reactive protein. This case-control study was designed to quantify the circulating levels of soluble co-stimulatory molecules by an in-house enzyme linked immunosorbent assay. A total of 314 subjects participated in the study including 100 patients and 214 normal controls. The statistical analysis was performed by Mann-Whitney test and Spearman's correlation rank test. Our results show increased plasma levels of sCD28, sCD86 (P = 0.0001) and decreased plasma levels of sCTLA-4 (P = 0.0018) in the patients compared with normal individuals. The levels of these factors were not related to the age of the patient, size of aneurysm or levels of C-reactive protein in plasma. There was, however, a significant inverse relationship between the concentrations of sCTLA-4 and sCD80 with matrix metalloproteinase-9. We suggest that soluble co-stimulatory molecules serve as biomarkers for the estimation of immune activation in AAA patients.
    Journal of Internal Medicine 04/2007; 261(4):399-407. · 6.46 Impact Factor
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    ABSTRACT: See also Santagostino E. Can the genetic profile predict inhibitor development in hemophilia A? This issue, pp 261–2.
    Journal of Thrombosis and Haemostasis 01/2007; 5(2):263 - 265. · 6.08 Impact Factor
  • Annals of the New York Academy of Sciences 12/2006; 636(1):9 - 19. · 4.38 Impact Factor
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    ABSTRACT: To describe two patients with myasthenia gravis (MG) and prolactinoma and analyze the associations between MG and prolactin (PRL) levels. Two case reports and a case-control study of PRL levels in 192 patients with MG. The Immunological Research Laboratory, Center for Molecular Medicine, Department of Medicine and the Department of Neurology, Karolinska Institutet, Stockholm, Sweden; St Petersburg Medical Academy for Postgraduate Studies, and St Petersburg State Medical Pediatric Academy, Russia. Two women with MG and thymic hyperplasia accompanied by prolactinomas are described. The levels of plasma PRL were raised in 101 women with MG, but not in 91 men. There was an association between high PRL levels and high levels of autoantibodies against the acetylcholine receptor. There is an association of MG with raised levels of PRL in women. PRL has stimulating effects on immune activation and the increased levels might thus be implied in the pathophysiology of MG.
    Acta Neurologica Scandinavica 12/2006; 114(5):346-9. · 2.47 Impact Factor
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    ABSTRACT: Wegener's granulomatosis (WG) is a chronic inflammatory disease characterized by granulomatosis inflammation, systemic vasculitis and glomerulonephritis. In patients, the peripheral T cells are characterized by mono/oligoclonal CD4+/CD8+ T-cell AV/BV receptor expansions, with aberrant expression of activation markers. This study was designed to characterize the phenotypic differences between the expanded and nonexpanded T-cell populations. Expression of markers for activation, costimulation and adhesion molecules was examined. As earlier studies have shown aberrant expression of CD28/CD152, we also analysed the expression of another costimulatory system, the tumour necrotic factor receptor (TNFR) superfamily proteins. Fluorocrome-conjugated monoclonal antibodies and flow cytometry was used to analyse the expression of the different markers on the surface of the expanded and nonexpanded subsets of T cells. The Karolinska Hospital and Karolinska Institutet in Stockholm, Sweden. Nine patients with WG (six men and three women) had 16 TCRAV/BV CD4+/CD8+ expanded populations that were characterized. The expanded TCRA/BV CD4+ and CD8+ cells had lower percentages of cells expressing CD28 and higher of those expressing CD152 (CTLA-4). The expanded CD4+ population had more cells expressing HLA-DR, CD57 and CCR5 (CD195), whilst the expression of CD25 was present on fewer of the expanded cells. The expanded CD8+ population contained more cells expressing CD137 (4-1BB), CD137 (4-1BBL), CD30 (Ki-1), CD40 and CD134 (OX40). There were marked differences in the phenotypes of expanded and nonexpanded T-cell populations.
    Journal of Internal Medicine 10/2006; 260(3):224-30. · 6.46 Impact Factor
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    ABSTRACT: Myasthenia gravis (MG) is commonly regarded as the prototype of an antibody-mediated, organ-specific autoimmune disease. Antibodies against the acetylcholine receptor (AChR) on the muscle endplate trigger its typical clinical manifestations of weakness and fatiguability. T-B cell interactions are thought to play a crucial role in the pathogenesis of MG. OX40 (CD134), a costimulatory molecule that is expressed on activated CD4+ T-cells, might contribute to the development or pathogenesis of immune-mediated diseases such as rheumatoid arthritis and graft-versus-host disease. In the present study, we investigated the expression of OX40 on CD4+ T-cells from patients with MG and healthy individuals. Results from 36 MG patients and 28 healthy controls revealed that more freshly isolated CD4+ T-cells from MG patients expressed OX40 than cells from healthy individuals. High levels of antibodies against the AChR, thymic hyperplasia and onset at an early age were associated with elevated expression of OX40. Upon activation by various concentrations of anti-CD3 antibodies, CD4+ T-cells from MG patients showed a tendency toward higher levels of OX40 expression than cells from healthy individuals. Given the role of OX40 in the immune system, we conclude that OX40 might contribute to the development of MG.
    Clinical & Experimental Immunology 02/2006; 143(1):110-6. · 3.41 Impact Factor
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    ABSTRACT: beta(2) Adrenoceptor (beta(2)-AR) represents a link between the sympathetic nervous system and the immune system, and may be involved in human rheumatoid arthritis (RA). The gene encoding beta(2)-AR contains three single nucleotide polymorphisms (SNPs) at amino acid positions 16, 27, and 164. To examine the common variants at positions 16 and 27 and their association with RA. An allele-specific polymerase chain reaction to determine the common variants at positions 16 and 27 was used in 154 patients with RA and 198 ethnically matched healthy subjects from northern Sweden. Carriage of Arg16 and of Gln27 was associated with RA. Carriage of Gln27 was associated with activity of the disease and in combination with non-carriage of Arg16 with higher levels of rheumatoid factor. The beta2-AR SNPs may thus constitute an additional non-major histocompatibility complex association in RA.
    Annals of the Rheumatic Diseases 06/2005; 64(5):773-6. · 9.11 Impact Factor
  • Ann Lefvert
    12/2004: pages 101-113;
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    ABSTRACT: Two pairs of monozygotic twins, discordant for myasthenia gravis (MG) for more than 30 years, were studied regarding T cell and antibody reactivity against disease related autoantigens, the acetylcholine receptor, one idiotypic and one anti-idiotypic human monoclonal antibody. The healthy and myasthenic twins had very similar autoantibody repertoires. IgG fractions from both healthy and myasthenic twins had the same capacity to decrease the free acetylcholine receptor content in mice after passive transfer. In comparison with their myasthenic sisters, the healthy twins had lower T cell responses against the acetylcholine receptor.
    Journal of Neuroimmunology 04/2004; 148(1-2):183-91. · 3.03 Impact Factor
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    ABSTRACT: The beta2-adrenergic receptor (beta2-AR) belongs to the group of G-protein-coupled receptors and is present on skeletal and cardiac muscle cells and on lymphocytes. The gene encoding beta2-AR (ADRB2) displays a moderate degree of heterogeneity in the human population and the distributions of single-nucleotide polymorphisms (SNPs) at amino acid positions 16, 27, and 164 are changed in asthma, obesity, and hypertension and in the autoimmune disease myasthenia gravis. An involvement of the beta2-AR has also been suggested in human rheumatoid arthritis (RA) and its animal model. We describe here an increased prevalence of the alleles Arg16 and Gln27 and a lower prevalence of homozygosis for Gly16 and Glu27 in patients with RA. Patients having the genotype combination GlyGly16-GlnGlu27 had higher levels of rheumatoid factor (RF) and a more active disease than other patients. Patients having the genotype Arg16-Gln27+ had higher levels of RF when compared to those having Arg16+Gln27+, and patients who were carriers of Gln27 had a more active disease than non-carriers of Gln27. Our results show an association of beta2-AR SNPs with RA in a population from the northern part of Sweden. Our study also confirms the strong linkage disequilibrium of genotypes at amino acid positions 16 and 27.
    Scandinavian Journal of Rheumatology 02/2004; 33(6):395-8. · 2.22 Impact Factor
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    ABSTRACT: To analyse the association of autoantibodies against cardiolipin (CL) and oxidized low density lipoproteins [copper-oxidized low density lipoprotein (oxLDL), malondialdehyde-modified LDL (MDA-LDL)] with rheumatoid arthritis (RA) and cardiovascular complications. One hundred and twenty-one patients with RA were consecutively included. Autoantibodies were determined by ELISA. Healthy individuals from the same region were used as controls. Levels of IgG, IgM and IgA antibodies against MDA-LDL and CL, as well as IgG and IgA antibodies against oxLDL were increased in the patients (P<0.01). The prevalence of IgG, IgM and IgA antibodies against CL was higher than in the normal population (74, 82 and 14%, respectively). The prevalence of IgG and IgA antibodies against oxLDL was also significantly increased (35 and 25%, respectively) and so was the prevalence of IgG and IgM antibodies against MDA-LDL (17 and 26%, respectively) compared with controls. The levels of IgM and IgA antibodies against aCL and IgM against MDA-LDL were increased in patients with extra-articular manifestations. Patients who developed myocardial infarction had a higher prevalence of IgG antibodies against MDA-LDL (P=0.04). There were substantial correlations between the levels of antibodies against oxLDL, MDA-LDL and CL. RA patients had increased levels and prevalence of autoantibodies against CL, oxLDL and MDA-LDL, with associations to severity of disease and cardiovascular complications.
    Rheumatology 10/2002; 41(9):988-95. · 4.21 Impact Factor
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    X B Wang, X Zhao, R Giscombe, A K Lefvert
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    ABSTRACT: CTLA-4 is an important negative regulator of the immune system. The regulation of the CTLA-4 gene (Ctla-4) transcription is poorly understood. A single nucleotide polymorphism (SNP) at -318 in the Ctla-4 promoter region is associated with certain autoimmune diseases. Since the -318 SNP occurs in a potential regulatory region, it is conceivable that the C' T transition may affect the expression of Ctla-4. In the present study, we show that the -318T allele is associated with a higher promoter activity than the -318C allele (8.13 +/- 0.46 vs 6.87 +/- 0.49). The presence of the -318T allele may thus contribute to up regulation of the expression of CTLA-4, and consequently represent one mechanism to inhibit exaggerated immune activity.
    Genes and Immunity 07/2002; 3(4):233-4. · 3.68 Impact Factor
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    ABSTRACT: The cytotoxic T lymphocyte associated protein 4 (CTLA-4) gene (Ctla-4) is a candidate gene for autoimmune disease. We here report results of two single nucleotide polymorphisms (SNPs) in the Ctla-4, a +49 A/G SNP in CDS1 and a C/T promoter SNP at position -318. There were no differences in these two SNPs between patients and healthy individuals. The frequency of allele G and genotype G/G at position +49 in CDS1 was increased in patients with thymoma when compared with patients with normal and hyperplastic thymic histopathology. Patients with the G/G genotype had signs of immune activation manifested as higher levels of serum IL-1beta and higher percentage of CD28(+) T lymphocytes. There was a strong linkage between the 86bp allele in the 3'-UTR and the A(+49) allele in CDS1. Our results suggest that the SNP at position +49 in CDS1 might be associated with the manifestations of MG.
    Genes and Immunity 03/2002; 3(1):46-9. · 3.68 Impact Factor

Publication Stats

3k Citations
732.73 Total Impact Points

Institutions

  • 2011
    • Shanghai University of Traditional Chinese Medicine
      Shanghai, Shanghai Shi, China
  • 1974–2011
    • Karolinska Institutet
      • • Center for Molecular Medicine - CMM
      • • Institutionen för medicin, Huddinge
      • • Department of Clinical Chemistry
      Solna, Stockholm, Sweden
  • 1998–2009
    • Sahlgrenska University Hospital
      • Department of Cardiology
      Goeteborg, Västra Götaland, Sweden
    • Swedish Institute for Communicable Disease Control
      Tukholma, Stockholm, Sweden
  • 2008
    • Shanghai Putuo District People's Hospital
      Shanghai, Shanghai Shi, China
  • 1978–2007
    • Karolinska University Hospital
      • • Department of Oncology
      • • Department of Clinical Chemistry
      Tukholma, Stockholm, Sweden
  • 2004
    • Red Cross
      Washington, Washington, D.C., United States
  • 2002
    • Umeå University
      Umeå, Västerbotten, Sweden
  • 1997
    • Södersjukhuset
      Tukholma, Stockholm, Sweden
  • 1991
    • Harvard Medical School
      • Division of Immunology
      Boston, Massachusetts, United States
  • 1988
    • Hebrew University of Jerusalem
      • Department of Pathology
      Jerusalem, Jerusalem District, Israel
  • 1981–1984
    • University of Geneva
      • Department of Biochemistry
      Genève, Geneva, Switzerland