By immunoprecipitation of recombinant GAD65 and GAD67 protein and protein fragments, 83% of sera from individuals with new-onset diabetes or prediabetes (n = 30) had GAD65 autoantibodies, but only 26% had GAD67 autoantibodies.
We measured insulin autoantibodies (IAAs), GAD autoantibodies (GAAs), and ICA512bdc autoantibodies (ICA512bdcAAs) by radioassay, in addition to ICAs, in 882 first-degree relatives of patients with type I diabetes, 50 of whom later developed diabetes with a median follow-up of 2.0 years (maximum 11.3 years).
The low prevalence of anti-GAD antibodies and HLA-DQA1 and DQB1 susceptibility alleles among recent-onset NIDDM patients, which was similar to observations in control subjects, suggests that diabetes in Korean adults is unlikely to have an autoimmune component to its pathogenesis.
We conclude that ICA+ relatives with GAD antibodies or low AIRg have a high risk for development of diabetes, but among ICA+ GAD+ relatives, the addition of IAA or a single determination of AIRg does not enhance the prediction of diabetes.
To investigate the role of CTLA4 in autoimmune diseases, we examined the correlation between CTLA4 gene polymorphism and the clinical characteristics of Japanese patients with type 1 diabetes, including the mode of onset of diabetes and presence of islet-specific autoantibodies (GAD, ICA 512 Ab) in the serum.
In the GAD-Ab positive subjects, earlier (32+/-3 years old) and abrupt onset (86%) of diabetes and insulin dependency (64%) were documented, as would be expected from the features of type 1 diabetes.
A potent mouse mAb (GAD6) to GAD65, and a rabbit polyclonal antibody (AB108) to GAD67, were used to standardize the reactivity of the diabetes sera with the mutant molecules.
Gliadin antibodies as well as the diabetes-related antibodies insulin autoantibody (IAA), GAD antibody (GADA), and tyrosin phosphatase IA2 antibody (IA-2A) were measured every 3 months; oral glucose tolerance tests were performed every 6 months.
While both isoforms of glutamic acid decarboxylase (GAD) function as important autoantigens in autoimmune diabetes mellitus-GAD65 in humans and GAD67 in the NOD mouse-GAD67 is not synthesized in human pancreatic islets and is thought not to be an autoantigen in human diabetes.
Offspring who were GAD or IA-2 autoantibody positive at birth (n = 678) had significantly lower risks for developing multiple islet autoantibodies (5-year risk 1.3%) and diabetes (8-year risk 1.1%) than offspring who were islet autoantibody negative at birth (5.3%, P = 0.008; and 3%, P = 0.04, respectively).
Children develop discrete, heterogeneous antibody responses to GAD that could arise from distinct immunization events, only some of which are diabetes relevant.
In type 1 diabetic patients, we found the INS mutation c.163C>T (R55C) in a girl who at 10 years of age presented with ketoacidosis and insulin-dependent, GAD, and insulinoma-associated antigen-2 (IA-2) antibody-negative diabetes.
Neither GAD- nor IA2-specific TCRs mediated T-cell islet infiltration or diabetes even though T-cells developed in these Rg mice and responded to their cognate epitope.
GAD positive (n=8) and GAD negative (n=8) subjects diagnosed with Type 2 diabetes were matched for age, gender, body mass index, duration of diabetes and glycaemic control.
They were detected in 55 of 128 (43%) children with autoantibodies to insulin, GAD and/or insulinoma-associated protein 2 and 34 of 42 (81%) who progressed to diabetes.
The AITD patients with GAD Ab were characterized by younger age at onset of diabetes, lower body mass index, higher hemoglobin A(1c) level, and higher frequency of insulin therapy than those without GAD Ab.
Both age of appearance of first autoantibody and insulin autoantibody (IAA) levels, but not GAD or IA-2 autoantibodies, were major determinants of the age of diabetes diagnosis (r = 0.79, P < 0.0001).
In 2 siblings with diabetes mellitus manifestation at age under 25 years, low fasting glucose levels, severely elevated glucose levels upon glucose challenge and absent autoantibodies for IA2 and GAD clarification for MODY was sought.
Upon stimulation with peptides, GAD-specific responses were equally broad in subjects with diabetes and healthy controls in the presence or absence of CD25(+) T cells, suggesting that a susceptible HLA is sufficient to generate a potentially autoreactive repertoire.