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Bearzatto, M.* ; Naserke, H.E.* ; Piquer, S.* ; Koczwara, K.* ; Lampasona, V.* ; Williams, A.* ; Christie, M.R.* ; Bingley, P.J.* ; Ziegler, A.-G.* ; Bonifacio, E.*

Two distinctly HLA-associated contiguous linear epitopes uniquely expressed within the islet antigen 2 molecule are major autoantibody epitopes of the diabetes-specific tyrosine phosphatase-like protein autoantigens.

J. Immunol. 168, 4202-4208 (2002)
PMC
Open Access Green as soon as Postprint is submitted to ZB.
The related tyrosine phosphatase-like proteins islet Ag (IA)-2 and IA-2beta are autoantigens of type 1 diabetes in humans. Autoantibodies are predominantly against IA-2, and IA-2-specific epitopes are major autoantibody targets. We used the close homology of IA-2 and IA-2beta to design chimeras and mutants to identify humoral IA-2-specific epitopes. Two major IA-2 epitopes that are absent from the related autoantigens IA-2beta and IA-2Delta 13 splice variant ICA512.bdc were found contiguous to each other within IA-2 juxtamembrane amino acids 611-620 (epitope JM1) and 621-630 (epitope JM2). JM1 and JM2 are recognized by sera from 67% of patients with IA-2 Abs, and relatives of patients with type 1 diabetes having Abs to either JM epitope had a >50% risk for developing type 1 diabetes within 6 years, even in the absence of diabetes-associated HLA genotypes. Remarkably, the presence of Abs to one of these two epitopes was mutually exclusive of the other; JM2 Abs and not JM1 Abs were found in relatives with HLA DR3/4, DR4/13, or DR1/4 genotypes; and the binding of autoantibodies to the JM2 epitope, but not the JM1 epitope, markedly affected proteolysis of IA-2. This is a unique demonstration of HLA-associated B cell responses to epitopes within a single autoantigen in humans and is consistent with modification of Ag processing by specific Ab-influencing peptide presentation by HLA molecules.
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Publication type Article: Journal article
Document type Scientific Article
ISSN (print) / ISBN 0022-1767
e-ISSN 1550-6606
Journal Journal of Immunology
Quellenangaben Volume: 168, Issue: 8, Pages: 4202-4208 Article Number: , Supplement: ,
Publisher American Association of Immunologists
Reviewing status Peer reviewed
Institute(s) Institute of Diabetes and Obesity (IDO)
Institute of Diabetes Research (IDF)
Institute of Pancreatic Islet Research (IPI)