Quantitative assay using recombinant human islet glutamic acid decarboxylase (GAD65) shows that 64K autoantibody positivity at onset predicts diabetes type.

At and before onset, most insulin-dependent diabetics (IDDM) have islet GAD65 autoantibodies (GAD65Ab). Since IDDM also occurs in older patients where non-insulin-dependent diabetes is common, we studied GAD65Ab at onset to classify diabetes type. Our quantitative immunoprecipitation assay uses recombinant human islet GAD65 stably expressed in hamster fibroblasts. Electrophoretic mobility was identical to native islet GAD65. Like native antigen, recombinant GAD65 migrated as two bands during electrophoresis, but converted to one under stronger reduction. Immunoprecipitation was linear with respect to antibody or antigen concentration. In 120 population-based diabetic patients of all ages grouped by treatment at onset and after 18 mo, GAD65Ab were present in 70% on insulin (n = 37), 10% on oral agent (n = 62, P < 0.0001), 69% changing from oral agent to insulin (n = 16, P < 0.001), and 1 of 33 controls. 65% with GAD65Ab, versus 8% without, changed from oral agent to insulin (P < 0.01). The GAD65Ab quantitative index was remarkably stable, and only 2 of 32 patients changed antibody status during follow-up. Concordance between GAD65Ab and islet cell antibodies was 93%. Quantitative correlation was approximate but significant. This highly sensitive, quantitative, high capacity assay for GAD65Ab reveals treatment requirements better than clinical criteria, perhaps guiding immunomodulatory therapy.

[1]  O. Madsen,et al.  Recombinant Glutamic Acid Decarboxylase (Representing the Single Isoform Expressed in Human Islets) Detects IDDM-Associated 64,000-Mr Autoantibodies , 1992, Diabetes.

[2]  M. Erlander,et al.  Two human glutamate decarboxylases, 65-kDa GAD and 67-kDa GAD, are each encoded by a single gene. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[3]  S. Bonner-Weir,et al.  Prognostically Significant Heterogeneity of Cytoplasmic Islet Cell Antibodies in Relatives of Patients with Type I Diabetes , 1992, Diabetes.

[4]  Å. Lernmark,et al.  Islet cell antibodies and fasting plasma C-peptide during the first 10 yr after diagnosis in patients with diabetes mellitus diagnosed in adult age , 1992 .

[5]  M. Erlander,et al.  Autoimmunity to two forms of glutamate decarboxylase in insulin-dependent diabetes mellitus. , 1992, The Journal of clinical investigation.

[6]  S. Baekkeskov,et al.  Pancreatic beta cells express two autoantigenic forms of glutamic acid decarboxylase, a 65-kDa hydrophilic form and a 64-kDa amphiphilic form which can be both membrane-bound and soluble. , 1991, The Journal of biological chemistry.

[7]  O. Madsen,et al.  Cloning, characterization, and autoimmune recognition of rat islet glutamic acid decarboxylase in insulin-dependent diabetes mellitus. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[8]  M. Rewers.  The changing face of the epidemiology of insulin-dependent diabetes mellitus (IDDM): research designs and models of disease causation. , 1991, Annals of medicine.

[9]  E. Mulvihill,et al.  Expression of recombinant human plasminogen in mammalian cells is augmented by suppression of plasmin activity. , 1991, The Journal of biological chemistry.

[10]  D. Porte.  β-cells in type II diabetes mellitus , 1991, Diabetes.

[11]  S. Baekkeskov,et al.  Identification of the 64K autoantigen in insulin-dependent diabetes as the GABA-synthesizing enzyme glutamic acid decarboxylase , 1990, Nature.

[12]  D. Daneman,et al.  Distinct antibody specificities to a 64-kD islet cell antigen in type 1 diabetes as revealed by trypsin treatment , 1990, The Journal of experimental medicine.

[13]  M. Atkinson,et al.  64 000 Mr autoantibodies as predictors of insulin-dependent diabetes , 1990, The Lancet.

[14]  D. Daneman,et al.  Persistence of Serum Antibodies to 64,000-Mr Islet Cell Protein After Onset of Type 1 Diabetes , 1990, Diabetes.

[15]  L. J. Nell,et al.  Autoantibodies present at onset of type I diabetes recognize multiple islet cell antigens. , 1990, Autoimmunity.

[16]  S. Baekkeskov,et al.  Identification of the 64K autoantigen in insulin-dependent diabetes as the GABA-synthesizing enzyme glutamic acid decarboxylase , 1990, Nature.

[17]  L. J. Nell,et al.  Antibodies against ganglioside GT3 in the sera of patients with type I diabetes mellitus. , 1989, Journal of immunology.

[18]  T. Kobayashi,et al.  Predictive value of insulin autoantibodies for further progression of beta cell dysfunction in non-insulin-dependent diabetics. , 1988, Diabetes research.

[19]  M. Atkinson,et al.  Autoantibodies in Nonobese Diabetic Mice Immunoprecipitate 64,000-Mr Islet Antigen , 1988, Diabetes.

[20]  T. Kobayashi,et al.  Time Course of Islet Cell Antibodies and β-Cell Function in Non-Insulin-Dependent Stage of Type I Diabetes , 1987, Diabetes.

[21]  C. de Beaufort,et al.  Antibodies to a 64,000 Mr human islet cell antigen precede the clinical onset of insulin-dependent diabetes. , 1987, The Journal of clinical investigation.

[22]  D. Gottlieb,et al.  Monoclonal antibodies to glutamic acid decarboxylase. , 1986, Proceedings of the National Academy of Sciences of the United States of America.

[23]  S. Baekkeskov,et al.  Autoantibodies to a 64-kilodalton islet cell protein precede the onset of spontaneous diabetes in the BB rat. , 1984, Science.

[24]  S. Baekkeskov,et al.  Autoantibodies in newly diagnosed diabetic children immunoprecipitate human pancreatic islet cell proteins , 1982, Nature.

[25]  C. Christiansen,et al.  Practical clinical value of the C-peptide response to glucagon stimulation in the choice of treatment in diabetes mellitus. , 2009, Acta medica Scandinavica.

[26]  C. Basilico,et al.  Temperature sensitive mutants of BHK cells affected in cell cycle progression , 1977, Journal of cellular physiology.