title: Analysis of the GAD65-GAD65 autoantibody interaction.
abstract: BACKGROUND
  GAD(65)Ab are important markers of risk of development of type 1 DM.
  
  
  METHODS
  With the need to improve the disease specificity of GAD(65)Ab measurement in mind, we have analysed the interaction between recombinant human GAD(65) and GAD(65)Ab from different groups of subjects in terms of association and dissociation rate constants and equilibrium constants. In addition, binding of GAD(65)Ab from various groups of subjects to wild-type GAD(65) versus GAD(65) containing a mutation E517P was studied.
  
  
  RESULTS
  Affinity constants for serum GAD(65)Ab in 12 type 1 DM patients ranged from 0.9 x 10(10) L/mol to 11.2 x 10(10) L/mol and from 0.8 x 10(10) L/mol to 14.0 x 10(10) L/mol in sera from 11 individuals without type 1 DM. Serum GAD(65)Ab concentrations assessed by Scatchard analysis ranged from 0.04 to 24.8 microg/mL in type 1 DM patients (n=12) and from 0.04 to 141.8 microg/mL in individuals without type 1 DM (n=11).
  
  
  CONCLUSIONS
  Overall, our study indicated that GAD(65)Ab in different patients studied showed similar association and dissociation rate constants and similar affinity constants. However, GAD(65)Ab concentrations vary widely between different sera. There was a modest reduction of the median binding of GAD(65)Ab to GAD(65) E517P in the group of patients with type 1 DM compared to patients without type 1 DM.
authors.affiliation: FIRS Laboratories, RSR Ltd., Parc Ty Glas, Llanishen, Cardiff, UK.
authors.forename: Graziella
authors.initials: G
authors.lastname: Coco
authors.forename: Shu
authors.initials: S
authors.lastname: Chen
authors.forename: Michael
authors.initials: M
authors.lastname: Powell
authors.forename: Helen
authors.initials: H
authors.lastname: Brooking
authors.forename: Renato
authors.initials: R
authors.lastname: Zanchetta
authors.forename: Corrado
authors.initials: C
authors.lastname: Betterle
authors.forename: Bernard Rees
authors.initials: BR
authors.lastname: Smith
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Furmaniak
mesh_terms: D000293:Adolescent; D000328:Adult; D000915:Antibody Affinity; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis* / Q000201:enzymology / Q000276:immunology; D005260:Female; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D001323:Autoantibodies; D011994:Recombinant Proteins; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2