IA-2 combined epitope assay: A new, highly sensitive approach to evaluate IA-2 humoral autoimmunity in type 1 diabetes

• Published in: Clinical immunology (Orlando, Fla.) Fla.), 2005-06, Vol.115 (3), p.260-267
• Main Authors: Tiberti, Claudio, Verrienti, Antonella, Fiore, Benedetta, Yu, Liping, Eisenbarth, George S., Dotta, Francesco, Di Mario, Umberto
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Amino Acid Sequence; Autoantibodies - immunology; Autoimmunity; Base Sequence; Biomarkers - blood; Child; Combined epitopes; Diabetes Mellitus, Type 1 - diagnosis; Diabetes Mellitus, Type 1 - genetics; Diabetes Mellitus, Type 1 - immunology; Epitopes - analysis; Epitopes - genetics; Epitopes - immunology; Female; Humans; Islet tyrosine phosphatase 2 (IA-2); Male; Membrane Proteins - analysis; Membrane Proteins - genetics; Membrane Proteins - immunology; Molecular Sequence Data; Protein Phosphatase 2; Protein Tyrosine Phosphatase, Non-Receptor Type 1; Protein Tyrosine Phosphatases - analysis; Protein Tyrosine Phosphatases - genetics; Protein Tyrosine Phosphatases - immunology; Receptor-Like Protein Tyrosine Phosphatases, Class 8; Sensitivity and Specificity; Type 1 diabetes
• ISSN: 1521-6616; 1521-7035
• DOI: 10.1016/j.clim.2005.01.015

Islet tyrosine phosphatase 2 (IA-2) is one of the major autoantigens in type 1 diabetes. The aim of this work was to evaluate which IA-2 construct(s) among those usually employed has the highest sensitivity and specificity for detecting IA-2 autoantibodies in autoimmune diabetes and whether the combination of different IA-2 constructs into a single assay allows the detection of immunoreactivities otherwise not detectable by a single construct. For this purpose, we tested the single immunoreactivities of IA-2 FL(aa 1–979), IA-2 BDC(aa 256–556:630–979), IA-2 IC(aa 605–979), IA-2(aa 256–760), IA-2(aa 761–928), and of 7 combinations of these fragments in the sera of 203 newly diagnosed type 1 diabetic patient (DM: 109 males,94 females, mean age 12.9 ± 7.5 years) and 43 prediabetic subject (PDM: 20 males, 23 females, mean age 10.3 ± 6.0 years) sera. IA-2 IC was the single construct that showed the highest sensitivity and specificity both in DM and PDM subjects; however, all of the other IA-2 constructs investigated detected additional immunoreactivities with respect to it. The combined use into the same assay of IA-2 IC, IA-2 FL, and IA-2 (256–760) constructs allowed detection of IA-2 Abs in additional 13.3% DM and 30.4% PDM subjects compared to the single IA-2 IC construct, suggesting this methodology as a new, highly sensitive approach to the study of IA-2 autoimmunity in type 1 diabetes.