Quantitative analysis of islet glutamic acid decarboxylase p64 autoantibodies in insulin-dependent diabetes mellitus.
Autoantibodies against the beta-cell M(r) 64,000 protein (p64), recently identified as an isoform of glutamic acid decarboxylase (GAD), are prevalent in patients with insulin-dependent diabetes mellitus (IDDM). Dog islets were found to represent an abundant source of native p64 allowing the study of antigen-antibody interactions in IDDM. A quantitative, standardized assay for p64 antibodies based on dog islets was developed and evaluated. Utilizing dog and human islets the p64 antibodies were detected in 17/19 (89%) new onset 15-32-year-old patients, compared to 15/19 (79%) in a rat islet assay. ICA were detected in 15/19 (79%) patients and correlated with the presence of p64 antibodies (rs = 0.59, P < 0.004) but not with age at onset, sex, or C-peptide levels. Sensitivity therefore is improved with the dog islet p64 antibody assay which will allow future studies requiring native p64 antigen in larger quantities are possible based on our findings.
Bärmeier
H
H
Dept. of Medicine, University of Washington, Seattle.
Ahlmén
J
J
Landin-Olsson
M
M
Rajotte
R V
RV
Sundkvist
G
G
Warnock
G
G
Lernmark
A
A
D000293:Adolescent; D000328:Adult; D000818:Animals; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000302:isolation & purification; D002096:C-Peptide / Q000097:blood; D011232:Chemical Precipitation; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D004285:Dogs; D005069:Evaluation Studies as Topic; D005260:Female; D005455:Fluorescent Antibody Technique; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D007118:Immunoassay / Q000379:methods / Q000592:standards; D007515:Islets of Langerhans / Q000276:immunology*; D008297:Male
D001323:Autoantibodies; D001324:Autoantigens; D002096:C-Peptide; C024211:islet cell antibody; D005968:Glutamate Decarboxylase