Autoantibodies to a 38-kDa glycosylated islet cell membrane-associated antigen in (pre)type 1 diabetes: association with IA-2 and islet cell autoantibodies.

OBJECTIVE: To study the association of autoantibodies against a 38-kDa glycated islet cell membrane-associated (GLIMA) protein with (pre)type 1 diabetes, patient characteristics, and other immune and genetic markers of the disease and to evaluate the possible added value of GLIMA antibody determinations for disease prediction and classification. RESEARCH DESIGN AND METHODS: Recent-onset type 1 diabetic patients (n = 100), prediabetic siblings (n = 23), and nondiabetic control subjects (n = 100) were consecutively recruited by the Belgian Diabetes Registry. GLIMA antibodies were determined by immunoprecipitation of radiolabeled islet cell proteins; islet cell antibodies (ICAs) were determined by indirect immunofluorescence; and insulin autoantibodies (IAAs), insulinoma-associated protein-2 antibodies (IA-2As), and GAD antibodies (GADAs) were determined by radioligand assays. RESULTS: GLIMA antibodies were detected in 38% of type 1 diabetic patients and 35% of prediabetic siblings (during follow-up) vs. 0% in control subjects (P < 0.001). Their prevalence was lower than that of other antibodies and was significantly associated with high levels of IA-2A and ICA (P < 0.0001). In (pre)diabetes, GLIMA antibodies could only be demonstrated in sera positive for > or = 1 other autoantibody. CONCLUSIONS: GLIMA antibodies are strongly associated with type 1 diabetes and antibody markers of rapid progression to clinical onset but have a lower diagnostic sensitivity for the disease than IAA, ICA, IA-2A, or GADA. In its present form, the GLIMA antibody assay does not provide much additional information for prediction or classification of diabetes, compared with that obtained from the measurement of IA-2As alone or in combination with IAAs, ICAs, and GADAs.

High frequency of persisting or increasing islet-specific autoantibody levels after diagnosis of type 1 diabetes presenting before 40 years of age. The Belgian Diabetes Registry.

OBJECTIVE: To study the presence and levels of GAD65 antibodies (GADA), IA-2 antibodies (IA-2-A), and islet cell antibodies (ICA) during the first years after clinical onset of type 1 diabetes in relation to age at diagnosis. RESEARCH DESIGN AND METHODS: Type 1 diabetic patients (n = 194) <40 years of age were consecutively recruited at the time of diagnosis by the Belgian Diabetes Registry and followed during the first 4 years of insulin treatment. ICA were determined by indirect immunofluorescence assay and IA-2-A, GADA, and insulin autoantibodies by a radioligand assay. RESULTS: Overall, 94% of initially antibody-positive patients (n = 180) remained positive for at least 1 antibody type 4 years after diagnosis. In the case of diagnosis after 7 years of age, GADA, IA-2-A, and ICA persisted in 91, 88, and 71%, respectively, of the initially antibody-positive patients. Antibody persistence was lower in those diagnosed at <7 years of age, amounting to 60% for GADA, 71% for IA-2-A, and 39% for ICA. In 57% of the initially antibody-positive patients, at least 1 type of autoantibody reached peak values after diagnosis. This occurred more frequently for clinical onset after 7 years of age and more often for GADA (49%) than for IA-2-A (29%) or ICA (19%). Of the patients, 24% that were negative for GADA at onset became GADA-positive during the following 4 years. Among the 7% initially antibody-negative patients, 2 of 14 subjects developed antibodies after clinical onset. CONCLUSIONS: In particular, for diagnosis after 7 years of age, islet cell-specific autoantibodies generally persist for many years after diagnosis. There is also a high frequency of increasing antibody levels and of conversion to antibody positivity in the first 4 years after diagnosis and start of insulin treatment. Thus, determination of antibodies at diagnosis can underestimate the number of cases with autoimmune type 1 diabetes, in particular with assays of lower sensitivity. The divergent temporal patterns of ICA, GADA, and IA-2-A suggest that the ICA test recognizes other antibody specificities besides GADA and IA-2-A and reflects other autoimmune processes; it also indicates that GADA assays have a higher diagnostic sensitivity in the period after clinical onset.

Use of an islet cell antibody assay to identify type 1 diabetic patients with rapid decrease in C-peptide levels after clinical onset. Belgian Diabetes Registry.

OBJECTIVE: To investigate whether the presence of antibody markers at diagnosis could help predict the rapid decrease in residual beta-cell function noted in some, but not all, patients with recent-onset type 1 diabetes. RESEARCH DESIGN AND METHODS: We measured random C-peptide levels (radioimmunoassay); islet cell cytoplasmic antibodies (ICA) (indirect immunofluorescence); and antibodies against IA-2 protein, 65-kDa glutamate decarboxylase, and insulin (liquid-phase radiobinding assays) in 172 patients <40 years of age with type 1 diabetes. The patients had been consecutively recruited at diagnosis by the Belgian Diabetes Registry and were followed for 2 years. RESULTS: Two years after diagnosis, random C-peptide levels had decreased significantly (P < 0.001) in ICA+ patients but not in ICA- patients. C-peptide values <50 pmol/ were noted in 88% of patients diagnosed before 7 years of age, in 45% of patients diagnosed between ages 7 and 15 years, and in 29% of patients diagnosed after 15 years of age (P < 0.001). In cases of clinical onset before age 15 years, a rapid decline in random C-peptide values was observed almost exclusively in patients with high-titer ICA (> or =50 Juvenile Diabetes Foundation [JDF] units) at diagnosis (69 vs. 17% in patients with lower ICA titers, P < 0.001). In patients diagnosed after 15 years of age, 36% of patients with ICA titers > or =12JDF units developed low C-peptide levels compared with 14% of patients with ICA titers < 12 JDF units (P < 0.03). Multivariate analysis confirmed that C-peptide levels after 2 years were inversely correlated with ICA levels (P < 0.001) and to a lesser degree positively correlated with age at diagnosis (P < 0.02), regardless of the levels or number of molecular autoantibodies. CONCLUSIONS: Young age at diagnosis and high-titer ICA identify a group of type 1 diabetic patients at high risk of rapidly losing residual beta-cell function. Using these selection criteria, it is possible to better target beta-cell-preserving interventions to patients with or without such rapid progression, depending on the nature of the tested substance. The ICA assay measures clinically relevant antibodies not detected in antibody assays that use recombinant human autoantigens for substrate.

The presence of thyrogastric antibodies in first degree relatives of type 1 diabetic patients is associated with age and proband antibody status.

A quarter of type 1 diabetic patients have thyrogastric autoantibodies (thyroid peroxidase and gastric parietal cell antibodies). Clinical, immune, and genetic risk factors help predict antibody status. First degree relatives of these patients may also frequently exhibit these antibodies. We assessed the prevalence of thyrogastric antibodies and dysfunction in first degree relatives in relation to age, gender, human leukocyte antigen-DQ type, beta-cell antibody (islet cell, glutamic acid decarboxylase-65, and tyrosine phosphatase antibodies), and proband thyrogastric antibody status. Sera from 272 type 1 diabetic patients (116 men and 156 women; mean age, 27 +/- 18 yr; duration, 10 +/- 9 y), 397 first degree relatives (192 men and 205 women; parents/siblings/offspring, 48/222/127; age, 22 +/- 10 yr), and 100 healthy controls were tested for islet cell antibodies and gastric parietal cell antibodies by indirect immunofluorescence and for tyrosine phosphatase, glutamic acid decarboxylase-65, and thyroid peroxidase antibodies by radiobinding assays. Glutamic acid decarboxylase-65 antibodies were present in 68% and 5%, islet cell antibodies were present in 36% and 2.5%, tyrosine phosphatase antibodies were present in 45% and 0.5%, thyroid peroxidase antibodies were present in 21% and 4.5%, and gastric parietal cell antibodies were present in 18% and 11% of diabetic patients and relatives, respectively. The presence of thyroid peroxidase antibodies in relatives was determined by age (beta = 0.22; P = 0.0001) and proband thyroid peroxidase antibodies status (beta = -2.6; P = 0.002; odds ratio = 11.1). Gastric parietal cell antibody positivity in relatives was associated with age (beta = 0.04; P = 0.026). Gastric parietal cell antibody-positive compared with gastric parietal cell antibody-negative relatives were more likely to have gastric parietal cell antibody-positive probands (P = 0.01; odds ratio = 3.0). beta-Cell antibody status and human leukocyte antigen-DQ type did not influence thyrogastric antibody status in relatives. (Sub)clinical dysthyroidism was found in 3%, iron deficiency anemia was present in 12% (26% gastric parietal cell antibody-positive and 9% gastric parietal cell antibody-negative subjects; P = 0.009), and pernicious anemia was found in 0.5% (5% gastric parietal cell antibody-positive and 0% gastric parietal cell antibody-negative subjects; P = 0.012) of relatives. They had less thyroid dysfunction (P < 0.0001) and pernicious anemia (P = 0.018) than diabetic probands. In conclusion, thyrogastric antibodies and dysfunction are more prevalent in type 1 diabetic patients than in first degree relatives. The presence of these antibodies in relatives is associated with age and proband antibody status, but not with beta-cell antibodies or human leukocyte antigen-DQ type.

Increased prevalence of abnormal immunoglobulin M, G, and A concentrations at clinical onset of insulin-dependent diabetes mellitus: a registry-based study. The Belgian Diabetes Registry.

In view of the reported association of insulin-dependent diabetes mellitus (IDDM) with viral infections, (non-) islet-specific immune changes, and partial immunodeficiencies, we used immunonephelometry to measure circulating levels of IgM, IgG, and IgA in a registry-based group of IDDM patients under age 40 years at clinical onset (n = 397) and in age-matched nondiabetic siblings (n = 316) and control subjects (n = 322). Overall, IgM and IgA concentrations were higher, and IgG concentrations lower, in patients than in control subjects or siblings (P < 0.001). In siblings, IgM concentrations were higher than in control subjects (P < 0.001). Using age-adjusted reference intervals, abnormal Ig concentrations were noted in 27% of the patients at onset versus only 10% of the siblings and 7% of the control subjects (P < 0.001). For onset between 20 and 40 years (n = 220), 30% of the patients presented either increased IgM levels (21%) or decreased IgG levels (11%). Both independent phenomena occurred regardless of diabetes-associated immune and genetic markers. In patients and siblings, IgM levels were positively correlated with pancreatic lipase activity. In diabetic children (0-9 years; n = 65), a subgroup presented increased IgA levels (15%) in association with the highest HLA DQ-linked genetic risk and elevated IgM levels. The changes in total Ig concentrations at onset were largely reversed under insulin therapy. They may reflect exposure to environmental triggers, such as viral infections, or to (relative) insulinopenia prior to clinical disease onset. Whatever their cause, different serum Ig levels exist in different age groups of recent-onset IDDM patients.

Gastric parietal cell antibodies are associated with glutamic acid decarboxylase-65 antibodies and the HLA DQA1*0501-DQB1*0301 haplotype in Type 1 diabetes mellitus. Belgian Diabetes Registry.

AIMS: To assess the prevalence of thyrogastric autoimmunity in relation to age, sex, beta-cell antibody status and HLA DQ haplotypes in Type 1 diabetes mellitus. METHODS: One hundred and seventy-one patients with Type 1 diabetes mellitus were studied (male/female 86/85; mean age 19 +/- 11 years; duration of diabetes 5 +/- 4 years). Islet cell antibodies (ICA) and parietal cell antibodies (PCA) were measured using indirect immunofluorescence; glutamic acid decarboxylase-65 antibodies (GADA) by radiobinding assay and thyroid peroxidase antibodies (TPO) with an immunoradiometric assay (IRMA). RESULTS: The majority of subjects (81.3%) showed one or more autoantibodies. The prevalence rates were: GADA 64.9%, ICA 46.2%, PCA 19.9% and TPO 19.3%. Patients with ICA+ > or = 3 years after diagnosis had a higher prevalence of GADA (P = 0.03, odds ratio (OR) 2.66) and thyrogastric antibodies (P = 0.05, OR 2.23) than subjects ICA- after 3 years. PCA+ patients were older (P = 0.04), had a higher prevalence of GADA (P = 0.005, OR 3.89) and TPO (P = 0.05, OR 2.50) than PCA- subjects. Logistic regression analysis showed that PCA status was determined by the HLA DQA1*0501-DQB1*0301 haplotype (beta = 2.94, P = 0.04) and GADA status (beta = 2.44, P = 0.041). CONCLUSIONS: Thyrogastric antibodies are highly prevalent in Type 1 diabetes mellitus, especially in patients with persisting ICA. Screening for gastric autoimmunity is particularly advised in patients who are positive for GADA and for the HLA DQA1*0501-DQB1*0301 haplotype.

CTLA-4 gene polymorphism confers susceptibility to insulin-dependent diabetes mellitus (IDDM) independently from age and from other genetic or immune disease markers. The Belgian Diabetes Registry.

Apart from genes in the HLA complex (IDDM1) and the variable number of tandem repeats in the 5' region of the insulin gene (INS VNTR, IDDM2), several other loci have been proposed to contribute to IDDM susceptibility. Recently, linkage and association have been shown between the cytotoxic T lymphocyte-associated protein 4 (CTLA-4) gene on chromosome 2q and IDDM. In a registry-based group of 525 recent-onset IDDM patients <40 years old we investigated the possible interactions of a CTLA-4 gene A-to-G transition polymorphism with age at clinical disease onset and with the presence or absence of established genetic (HLA-DQ, INS VNTR) and immune disease markers (autoantibodies against islet cell cytoplasm (ICA); insulin (IAA); glutamate decarboxylase (GAD65-Ab); IA-2 protein tyrosine phosphatase (IA-2-Ab)) determined within the first week of insulin treatment. In new-onset IDDM patients. G-allele-containing CTLA-4 genotypes (relative risk (RR)= 1.5; 95% confidence interval (CI) = 1.2-2.0; P < 0.005) were not preferentially associated with age at clinical presentation or with the presence of other genetic (HLA-DR3 or DR4 alleles; HLA-DQA1*0301-DQB1*0302 and/or DQA1*0501-DQB1*0201 risk haplotypes; INS VNTR I/I risk genotype) or immune (ICA, IAA, IA-2-Ab, GAD65-Ab) markers of diabetes. For 151 patients, thyrogastric autoantibodies (anti-thyroid peroxidase, anti-thyroid-stimulating hormone (TSH) receptor, anti-parietal cell, anti-intrinsic factor) were determined, but association between CTLA-4 risk genotypes and markers of polyendocrine autoimmunity could not be demonstrated before or after stratification for HLA- or INS-linked risk. In conclusion, the presence of a G-containing CTLA-4 genotype confers a moderate but significant RR for IDDM that is independent of age and genetic or immune disease markers.

Beta-cell, thyroid, gastric, adrenal and coeliac autoimmunity and HLA-DQ types in type 1 diabetes.

The autoimmune attack in type 1 diabetes is not only targeted to beta cells. We assessed the prevalence of thyroid peroxidase (aTPO), parietal cell (PCA), antiadrenal (AAA) and endomysial antibodies (EmA-IgA), and of overt autoimmune disease in type 1 diabetes, in relation to gender, age, duration of disease, age at onset, beta-cell antibody status (ICA, GADA, IA2A) and HLA-DQ type. Sera from 399 type 1 diabetic patients (M/F: 188/211; mean age: 26 +/- 16 years; duration: 9 +/- 8 years) were tested for ICA, PCA, AAA and EmA-IgA by indirect immunofluorescence, and for IA2A (tyrosine phosphatase antibodies), GADA (glutamic acid decarboxylase-65 antibodies) and aTPO by radiobinding assays. The prevalence rates were: GADA 70%; IA2A, 44%; ICA, 39%; aTPO, 22%; PCA, 18%; EmA-IgA, 2%; and AAA, 1%. aTPO status was determined by female gender (beta = - 1.15, P = 0.002), age (beta = 0.02, P = 0.01) and GADA + (beta = 1.06, P = 0.02), but not by HLA-DQ type or IA2A status. Dysthyroidism (P < 0.0001) was more frequent in aTPO + subjects. PCA status was determined by age (beta = 0.03, P = 0.002). We also observed an association between PCA + and GADA + (OR = 1.9, P = 0.049), aTPO + (OR = 1.9, P = 0.04) and HLA DQA1*0501-DQB1*0301 status (OR = 2.4, P = 0.045). Iron deficiency anaemia (OR = 3.0, P = 0.003) and pernicious anaemia (OR = 40, P < 0.0001) were more frequent in PCA + subjects. EmA-IgA + was linked to HLA DQA1*0501-DQB1*0201 + (OR = 7.5, P = 0.039), and coeliac disease was found in three patients. No patient had Addison's disease. In conclusion, GADA but not IA2A indicate the presence of thyrogastric autoimmunity in type 1 diabetes. aTPO have a female preponderance, PCA are weakly associated with HLA DQA1*0501-DQB1*0301 and EmA-IgA + with HLA DQA1*0501-DQB1*0201.