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Diagnostic sensitivity of immunodominant epitopes of glutamic acid decarboxylase (GAD65) autoantihodies in childhood IDDM

Falorni, A. ; Ackefors, M. ; Carlberg, C. ; Daniels, T. ; Persson, B. ; Robertson, J. and Lernmark, Å LU (1996) In Diabetologia 39(9). p.1091-1098
Abstract

The prevalence and titre of epitope-specific autoantibodies to glutamic acid decarboxylase (GAD65) in 155 insulin-dependent diabetic (IDDM) and 9 GAD65 antibody (Ab)-positive healthy children were determined using four GAD65/67 chimaeric molecules which discriminate among the N-terminal (N), middle (M) and C-terminal (C) epitopes of GAD65. Radioligand binding assays for IgG Ab used immunoprecipitation of in vitro translated 35S-GAD. We found autoantibodies to GAD65 in 116 of 155 (75 %), to GAD67 in 19 of 155 (12 %) (p < 0.0001) and to the GAD65-N-67 chimaera in 25 of 155 (16 %) (p < 0.0001) IDDM sera. GAD67Ab were found almost exclusively (17 of 19, 89 %) in GAD65Ab-positive sera and the levels of GAD67Ab correlated... (More)

The prevalence and titre of epitope-specific autoantibodies to glutamic acid decarboxylase (GAD65) in 155 insulin-dependent diabetic (IDDM) and 9 GAD65 antibody (Ab)-positive healthy children were determined using four GAD65/67 chimaeric molecules which discriminate among the N-terminal (N), middle (M) and C-terminal (C) epitopes of GAD65. Radioligand binding assays for IgG Ab used immunoprecipitation of in vitro translated 35S-GAD. We found autoantibodies to GAD65 in 116 of 155 (75 %), to GAD67 in 19 of 155 (12 %) (p < 0.0001) and to the GAD65-N-67 chimaera in 25 of 155 (16 %) (p < 0.0001) IDDM sera. GAD67Ab were found almost exclusively (17 of 19, 89 %) in GAD65Ab-positive sera and the levels of GAD67Ab correlated with those of GAD65Ab (r2=0.5913; p=0.009). GAD65Ab directed to GAD65-M were found in 104 of 155 (67 %), to GAD65-C in 104 of 155 (67 %) and to GAD65-M + C in 116 of 155 (75 %) of IDDM sera. and indicated reactivity to at least two distinct epitopes. Among the nine GAD65Ab-positive healthy children, two (22 %) were also positive with GAD67, nine (100 %) with GAD65-M + C, seven (78 %) with GAD65-M, eight (89 %) with GAD65-C and two (22 %) with GAD65-N-67. Titres of GAD65Ab (p = 0.007), GAD65-C-Ab (p = 0.002) and GAD65C+M-Ab (p=0.101), but not of GAD65-M-Ab (p = 0.101) were significantly higher in IDDM than in healthy children. We conclude that GAD65Ab in IDDM and healthy children are directed to middle and C-terminal epitopes, and propose that levels of antibodies specifically directed to the carboxy-terminal end of GAD65 may distinguish IDDM from healthy children.

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author
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publishing date
type
Contribution to journal
publication status
published
subject
keywords
Autoantibodies, Autoimmunity, Insulin-dependent diabetes mellitus, Radioimmunoassay, Recombinant protein
in
Diabetologia
volume
39
issue
9
pages
1091 - 1098
publisher
Springer
external identifiers
  • pmid:8877294
  • scopus:0029793724
ISSN
0012-186X
DOI
10.1007/BF00400659
language
English
LU publication?
no
id
fa8f67be-bc84-44fe-a6c6-1adc694e88b2
date added to LUP
2019-07-01 13:26:56
date last changed
2021-02-17 02:13:36
@article{fa8f67be-bc84-44fe-a6c6-1adc694e88b2,
  abstract     = {<p>The prevalence and titre of epitope-specific autoantibodies to glutamic acid decarboxylase (GAD65) in 155 insulin-dependent diabetic (IDDM) and 9 GAD65 antibody (Ab)-positive healthy children were determined using four GAD65/67 chimaeric molecules which discriminate among the N-terminal (N), middle (M) and C-terminal (C) epitopes of GAD65. Radioligand binding assays for IgG Ab used immunoprecipitation of in vitro translated <sup>35</sup>S-GAD. We found autoantibodies to GAD65 in 116 of 155 (75 %), to GAD67 in 19 of 155 (12 %) (p &lt; 0.0001) and to the GAD65-N-67 chimaera in 25 of 155 (16 %) (p &lt; 0.0001) IDDM sera. GAD67Ab were found almost exclusively (17 of 19, 89 %) in GAD65Ab-positive sera and the levels of GAD67Ab correlated with those of GAD65Ab (r<sup>2</sup>=0.5913; p=0.009). GAD65Ab directed to GAD65-M were found in 104 of 155 (67 %), to GAD65-C in 104 of 155 (67 %) and to GAD65-M + C in 116 of 155 (75 %) of IDDM sera. and indicated reactivity to at least two distinct epitopes. Among the nine GAD65Ab-positive healthy children, two (22 %) were also positive with GAD67, nine (100 %) with GAD65-M + C, seven (78 %) with GAD65-M, eight (89 %) with GAD65-C and two (22 %) with GAD65-N-67. Titres of GAD65Ab (p = 0.007), GAD65-C-Ab (p = 0.002) and GAD65C+M-Ab (p=0.101), but not of GAD65-M-Ab (p = 0.101) were significantly higher in IDDM than in healthy children. We conclude that GAD65Ab in IDDM and healthy children are directed to middle and C-terminal epitopes, and propose that levels of antibodies specifically directed to the carboxy-terminal end of GAD65 may distinguish IDDM from healthy children.</p>},
  author       = {Falorni, A. and Ackefors, M. and Carlberg, C. and Daniels, T. and Persson, B. and Robertson, J. and Lernmark, Å},
  issn         = {0012-186X},
  language     = {eng},
  month        = {01},
  number       = {9},
  pages        = {1091--1098},
  publisher    = {Springer},
  series       = {Diabetologia},
  title        = {Diagnostic sensitivity of immunodominant epitopes of glutamic acid decarboxylase (GAD65) autoantihodies in childhood IDDM},
  url          = {http://dx.doi.org/10.1007/BF00400659},
  doi          = {10.1007/BF00400659},
  volume       = {39},
  year         = {1996},
}