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  • 1
    Electronic Resource
    Electronic Resource
    Antibodies to β2-Glycoprotein-I: Urea Resistance, Binding Specificity, and Association with Thrombosis (1998)
    Springer
    Journal of clinical immunology 18 (1998), S. 380-391 
    Details
    ISSN: 1573-2592
    Keywords: Anti-β2glycoprotein-I ; antibodies ; antiphospholipid syndrome ; urea resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to evaluate the urea resistance and binding characteristics of anti-β2-glycoprotein I (anti-β2GPI) antibodies using standard anticardiolipin (aCL) and anti-β2GPI enzyme immunosorbent assays (ELISAs). Sera from patients with antiphospholipid syndrome (APS) (n = 22) and non-APS (n = 24), positive in a standard aCL ELISA, were tested in an anti-β2GPI ELISA performed in polystyrene-irradiated ELISA plates. Urea resistance aCL and anti-β2GPI ELISAs were performed by measuring the ability of antibodies to recognize antigen in the presence of 2 M urea. The serum dilution after urea treatment (D) expressed as a percentage of the serum dilution without urea treatment (D o) corresponding to the same optical density was defined as residual activity (RA = 100 D/D o). The higher the RA, the higher the resistance of the antibodies to urea. APS compared to non-APS sera had higher aCL binding (absorbance values ranging between 0.180 and 1.400; median, 0.717 vs 0.120–1.273; median, 0.250, respectively; P 〈 0.004). Six APS patients' sera had low aCL levels but they expressed RA ≥30%. Anti-β2GPI antibodies were detected in 15 of 22 APS vs 3 of 24 non-APS patients (P 〈 0.03); RA ≥30% was detected in 15 of 22 APS vs 1 of 23 non-APS patients (P 〈 0.004). Using a CL affinity column, antibodies were purified from three APS anti-β2GPI negative and three non-APS anti-β2GPI-positive patients and tested in a aCL ELISA, using highly purified bovine serum albumin (BSA) as a blocking agent (modified ELISA); reactivity was not detected in two APS and one non-APS sera. On the contrary, the reactivity of the purified antibodies was high when β2GPI was incubated with CL in the ELISA plates; thus some anti-β2GPI negative sera from APS patients recognized the CL/β2GPI complex, rather than CL or β2GPI alone. In conclusion, anti-β 2GPI antibodies are common in the APS patients, but a number of such patients recognize the CL/β2GPI complex and not CL or β2GPI. Antibodies to either β2GPI or the CL/β2GPI complex derived from APS sera present a high resistance to urea. Anti-β2GPI antibodies of low urea resistance exist in a minority of non-APS patients with autoimmune disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023274505128
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The PPGMRPP repetitive epitope of the Sm autoantigen: Antigenic specificity induced by conformational changes. Application of the Sequential Oligopeptide Carriers (SOCs) (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 447-454 
    Details
    ISSN: 1573-3904
    Keywords: Antigenicity of the Sm epitope ; Carriers of antigenic peptides ; Peptide conformation ; Proline-rich Sm epitope ; Sm autoantigen ; Systemic lupus erythematosus (SLE)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The PPGMRPP sequence, found in several copies in the Sm and U1RNP autoantigens, is the main target of anti-Sm and anti-U1RNP antibodies in systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD) patient's sera. It is also recognized, to a lower extent, by anti-Ro/SSA and anti-La/SSB specificities. The PPGMRPP-NH2 peptide amide and the PPGMRPP peptide, which is bound to a pentameric sequential oligopeptide carrier (SOC5), were examined by1H-NMR spectroscopy and ELISA assays, using sera from patients with autimmune rheumatic diseases. Among the three main conformers found for the free PPGMRPP, the extended one was also identified for PPGMRPP-NH2 and (PPGMRPP)5-SOC5. This can be attributed to the absence of ionic interactions between the Arg-guanidinium and the carboxylate group in the amide and SOC5-bound forms of the peptide. Immunoassays using sera from various specificities showed an enhanced anti-Sm and anti-U1RNP recognition of PPGMRPP-NH2 and (PPGMRPP)5-SOC5, and lowering of the anti-Ro/SSA and anti-La/SSB reactivity. The presence of multiple conformers of free PPGMRPP may explain the unexpected cross-reactivity to the anti-Ro/La positive sera, while the prevalence of the extended conformation in PPGMRPP-NH2 and (PPGMRPP)5-SOC5 is mainly responsible for the enhanced recognition from the anti-Sm and anti-U1RNP autoantibodies. it is concluded that the antigenic specificity of PPGMRPP-NH2 and (PPGMRPP)5-SOC5 is mainly induced by conformational changes resulting from the conversion of the C-terminal carboxylate group to the amide form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442915
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The PPGMRPP repetitive epitope of the Sm autoantigen: Antigenic specificity induced by conformational changes. Application of the Sequential Oligopeptide Carriers (SOCs) (1997)
    Springer
    International journal of peptide research and therapeutics 4 (1997), S. 447-454 
    Details
    ISSN: 1573-3904
    Keywords: Antigenicity of the Sm epitope ; Carriers of antigenic peptides ; Peptide conformation ; Proline-rich Sm epitope ; Sm autoantigen ; Systemic lupus erythematosus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The PPGMRPP sequence, found in several copies in the Sm and U1RNPautoantigens, is the main target of anti-Sm and anti-U1RNP antibodies insystemic lupus erythematosus (SLE) and mixed connective tissue disease(MCTD) patient's sera. It is also recognized, to a lower extent, byanti-Ro/SSA and anti-La/SSB specificities. The PPGMRPP-NH2peptide amide and the PPGMRPP peptide, which is bound to a pentamericsequential oligopeptide carrier (SOC5), were examined by1H-NMR spectroscopy and ELISA assays, using sera from patientswith autoimmune rheumatic diseases. Among the three main conformers foundfor the free PPGMRPP, the extended one was also identified for PPGMRPP-NH2 and (PPGMRPP)5-SOC5.This can be attributed to the absence of ionic interactions between theArg-guanidinium and the carboxylate group in the amide andSOC5-bound forms of the peptide. Immunoassays using sera fromvarious specificities showed an enhanced anti-Sm and anti-U1RNP recognitionof PPGMRPP-NH2 and(PPGMRPP)5-SOC5, and lowering of the anti-Ro/SSAand anti-La/SSB reactivity. The presence of multiple conformers of freePPGMRPP may explain the unexpected cross-reactivity to the anti-Ro/Lapositive sera, while the prevalence of the extended conformation inPPGMRPP-NH2 and (PPGMRPP)5-SOC5is mainly responsible for the enhanced recognition from the anti-Sm andanti-U1RNP autoantibodies. It is concluded that the antigenic specificity ofPPGMRPP-NH2 and (PPGMRPP)5-SOC5 ismainly induced by conformational changes resulting from the conversion ofthe C-terminal carboxylate group to the amide form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008838516616
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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