Antibodies to deamidated gliadin peptide in diagnosis of celiac disease in children.

OBJECTIVES: Determination of antibodies to synthetic deamidated gliadin peptides (anti-DGPs) may work as an alternative or complement the commonly used test for tissue transglutaminase antibodies (TGA) in the diagnosis of celiac disease (CD). We analyzed the performance of a time-resolved immunofluorometric anti-DGP assay (TR-IFMA) in the diagnosis of CD in children and also retrospectively analyzed the appearance of anti-DGP antibodies before TGA seroconversion. METHODS: The study included 92 children with biopsy-confirmed CD. Serum samples were taken at the time or just before the clinical diagnosis. The control group comprised 82 TGA-negative children who were positive for human leucocyte antigen-DQ2 or -DQ8. RESULTS: Based on receiver operating characteristic curves, the optimal cutoff value for immunoglobulin (Ig) A anti-DGP positivity was 153 arbitrary units (AUs) with a sensitivity of 92.4% and specificity of 97.6% and that for IgG anti-DGP 119 AU, with a sensitivity of 97.8% and specificity of 97.6%. All 92 children with CD were either IgA or IgG anti-DGP positive at the time of diagnosis. Sera from 48 children with CD were also analyzed retrospectively before the diagnosis. Anti-DGP antibodies preceded TGA positivity in 35 of the 48 children with CD and appeared a median of 1 year earlier. CONCLUSIONS: The TR-IFMA assay for detecting anti-DGP antibodies shows high sensitivity and specificity for the diagnosis of CD in children. In a majority of our study population, anti-DGP seropositivity preceded TGA positivity, indicating that earlier detection of CD may be possible by monitoring anti-DGP antibodies frequently in genetically susceptible children.

Association of human bocavirus 1 infection with respiratory disease in childhood follow-up study, Finland.

Human bocavirus 1 (HBoV1) DNA is frequently detected in the upper airways of young children with respiratory symptoms. Because of its persistence and frequent co-detection with other viruses, however, its etiologic role has remained controversial. During 2009-2011, using HBoV1 IgM, IgG, and IgG-avidity enzyme immunoassays and quantitative PCR, we examined 1,952 serum samples collected consecutively at 3- to 6-month intervals from 109 constitutionally healthy children from infancy to early adolescence. Primary HBoV1 infection, as indicated by seroconversion, appeared in 102 (94%) of 109 children at a mean age of 2.3 years; the remaining 7 children were IgG antibody positive from birth. Subsequent secondary infections or IgG antibody increases were evident in 38 children and IgG reversions in 10. Comparison of the seroconversion interval with the next sampling interval for clinical events indicated that HBoV1 primary infection, but not secondary immune response, was significantly associated with acute otitis media and respiratory illness.

Early suppression of immune response pathways characterizes children with prediabetes in genome-wide gene expression profiling.

Type 1 diabetes (T1D) is caused by autoimmune destruction of insulin-producing pancreatic beta cells in the islets of Langerhans. Although defects in various T cell subsets have been linked to the disease pathogenesis, mechanisms initiating or enhancing the autoimmunity in prediabetes remain poorly understood. To unravel genes and molecular pathways affected by the diabetes-associated autoimmunity, we investigated transcriptomic profiles of prospective whole-blood samples from children who have developed T1D-associated autoantibodies and eventually clinical T1D. Gene-level investigation of the data showed systematic differential expression of 520 probesets. A network-based analysis revealed then a highly significant down-regulated network of genes involved in antigen presentation as well as T-cell receptor and insulin signaling. Finally, detection of dynamic changes in the affected pathways at the early or late phases of autoimmunity showed down-regulation of several novel T1D-associated pathways as well as known key components of immune response. The longitudinal genome-wide data generated in the present study allows the detection of dynamic changes relevant to the disease that may be completely missed in conventional cross-sectional studies or in genome-wide association studies. Taken together, our analysis showed systemic high-level repression of immune response pathways associated with T1D autoimmunity.

Enterovirus Infections Are Associated With the Development of Celiac Disease in a Birth Cohort Study.

Enterovirus and adenovirus infections have been linked to the development of celiac disease. We evaluated this association in children who developed biopsy-proven celiac disease (N = 41) during prospective observation starting from birth, and in control children (N = 53) matched for the calendar time of birth, sex, and HLA-DQ genotype. Enterovirus and adenovirus infections were diagnosed by seroconversions in virus antibodies in longitudinally collected sera using EIA. Enterovirus infections were more frequent in case children before the appearance of celiac disease-associated tissue transglutaminase autoantibodies compared to the corresponding period in control children (OR 6.3, 95% CI 1.8-22.3; p = 0.005). No difference was observed in the frequency of adenovirus infections. The findings suggest that enterovirus infections may contribute to the process leading to celiac disease.

Nasal insulin to prevent type 1 diabetes in children with HLA genotypes and autoantibodies conferring increased risk of disease: a double-blind, randomised controlled trial.

BACKGROUND: In mouse models of diabetes, prophylactic administration of insulin reduced incidence of the disease. We investigated whether administration of nasal insulin decreased the incidence of type 1 diabetes, in children with HLA genotypes and autoantibodies increasing the risk of the disease. METHODS: At three university hospitals in Turku, Oulu, and Tampere (Finland), we analysed cord blood samples of 116 720 consecutively born infants, and 3430 of their siblings, for the HLA-DQB1 susceptibility alleles for type 1 diabetes. 17 397 infants and 1613 siblings had increased genetic risk, of whom 11 225 and 1574, respectively, consented to screening of diabetes-associated autoantibodies at every 3-12 months. In a double-blind trial, we randomly assigned 224 infants and 40 siblings positive for two or more autoantibodies, in consecutive samples, to receive short-acting human insulin (1 unit/kg; n=115 and n=22) or placebo (n=109 and n=18) once a day intranasally. We used a restricted randomisation, stratified by site, with permuted blocks of size two. Primary endpoint was diagnosis of diabetes. Analysis was by intention to treat. The study was terminated early because insulin had no beneficial effect. This study is registered with ClinicalTrials.gov, number NCT00223613. FINDINGS: Median duration of the intervention was 1.8 years (range 0-9.7). Diabetes was diagnosed in 49 index children randomised to receive insulin, and in 47 randomised to placebo (hazard ratio [HR] 1.14; 95% CI 0.73-1.77). 42 and 38 of these children, respectively, continued treatment until diagnosis, with yearly rates of diabetes onset of 16.8% (95% CI 11.7-21.9) and 15.3% (10.5-20.2). Seven siblings were diagnosed with diabetes in the insulin group, versus six in the placebo group (HR 1.93; 0.56-6.77). In all randomised children, diabetes was diagnosed in 56 in the insulin group, and 53 in the placebo group (HR 0.98; 0.67-1.43, p=0.91). INTERPRETATION: In children with HLA-conferred susceptibility to diabetes, administration of nasal insulin, started soon after detection of autoantibodies, could not be shown to prevent or delay type 1 diabetes.

Role of insulin autoantibody affinity as a predictive marker for type 1 diabetes in young children with HLA-conferred disease susceptibility.

BACKGROUND: Insulin autoantibodies (IAA) are early markers of prediabetic autoimmunity. As transient and fluctuating IAA positivity are common among young children, distinguishing non-progressive IAA from destruction-related IAA is essential when preventive measures are considered. We tested whether children progressing rapidly to type 1 diabetes (progressors) are characterized by a higher prediabetic IAA affinity than IAA-positive children remaining unaffected or progressing more slowly to diabetes (non-progressors), and whether IAA affinity increases towards diagnosis. METHODS: Finnish children with HLA-conferred diabetes susceptibility were observed from birth for diabetes-associated autoantibodies and progression to overt type 1 diabetes. IAA levels and affinities of the first IAA-positive prediabetic samples and samples obtained closest to the diagnosis in 64 progressors were compared with corresponding values in 64 matched IAA-positive non-progressors. RESULTS: The median age at diagnosis was 3.9 years in progressors and the median follow-up time 7.6 years among unaffected subjects. In the first samples the median IAA affinity was 1.4 x 10(10) L/mol in both groups (p = 0.33), while at the second sampling it was 1.1 x 10(10) L/mol in progressors and 1.2 x 10(10) L/mol in unaffected subjects (p = 0.46). No changes in affinity levels were observed (p = 0.33 and p = 0.84, respectively). IAA titers increased towards diagnosis among progressors (from a median of 13.6 to 20.1 relative units; p = 0.02). CONCLUSIONS: Among young IAA-positive children with HLA-conferred disease susceptibility IAA affinity failed to distinguish rapid progressors from slowly or non-progressing subjects. In relation to IAA affinity, no maturation of the humoral immune response was observed over time from seroconversion to diagnosis.

Persistent Alterations in Plasma Lipid Profiles Before Introduction of Gluten in the Diet Associated With Progression to Celiac Disease.

OBJECTIVES: Celiac disease (CD) is a chronic enteropathy characterized by an autoimmune reaction in the small intestine of genetically susceptible individuals. The underlying causes of autoimmune reaction and its effect on host metabolism remain largely unknown. Herein, we apply lipidomics to elucidate the early events preceding clinical CD in a cohort of Finnish children, followed up in the Type 1 Diabetes Prediction and Prevention study. METHODS: Mass spectrometry-based lipidomics profiling was applied to a longitudinal/prospective series of 233 plasma samples obtained from CD progressors (n = 23) and healthy controls (n = 23), matched for human leukocyte antigen (HLA) risk, sex, and age. The children were followed from birth until diagnosis of clinical CD and subsequent introduction of a gluten-free diet. RESULTS: Twenty-three children progressed to CD at a mean age of 4.8 years. They showed increased amounts of triacylglycerols (TGs) of low carbon number and double bond count and a decreased level of phosphatidylcholines by age 3 months as compared to controls. These differences were exacerbated with age but were not observed at birth (cord blood). No significant differences were observed in the essential TGs. DISCUSSION: Our preliminary findings suggest that abnormal lipid metabolism associates with the development of clinical CD and occurs already before the first introduction of gluten to the diet. Moreover, our data suggest that the specific TGs found elevated in CD progressors may be due to a host response to compromised intake of essential lipids in the small intestine, requiring de novo lipogenesis.

Early epitope- and isotype-specific humoral immune responses to GAD65 in young children with genetic susceptibility to type 1 diabetes.

OBJECTIVE: The pattern of the humoral immunity to disease-associated autoantigens may reflect the severity of the autoimmune disease process. The purpose of this study was to delineate the maturation of the humoral immunity to one of the main autoantigens in type 1 diabetes (T1D), glutamic acid decarboxylase (GAD65). DESIGN AND METHODS: Serum samples were obtained for the detection of epitope- and isotype-specific antibodies sequentially with short intervals from 36 young children with HLA-conferred genetic susceptibility to T1D starting from the first appearance of GAD65Ab. During prospective observation, ten children developed T1D. Antibodies were analyzed using biotinylated anti-human immunoglobulin (Ig) antibodies and chimeric GAD molecules in radio-binding assays. RESULTS: The immune response to GAD65 started as reactivity to the middle region and spread rapidly to the C-terminal region. IgG1 antibodies dominated among the isotypes from the first appearance of GAD65Ab, while other IgG subclasses were observed to a lesser extent. IgG4 antibodies emerged clearly as the last IgG subclass. A broad initial response comprising three to four IgG subclasses and the lack of an emerging IgG4 response during follow-up was associated with increased risk for progression to clinical diabetes (P<0.05). CONCLUSIONS: The humoral response to GAD65 epitope clusters is relatively uniform in young children, whereas there is conspicuous individual variation in IgG subclass responses except for IgG1. A narrow initial IgG subclass response to GAD65 and the emergence of IgG4 antibodies were characteristic of those who remained non-diabetic over the first few years of GAD65 autoimmunity.

Time-resolved fluorescence imaging of islet cell autoantibodies.

Time-resolved fluorescence of lanthanide chelates has been widely used in bioanalytical assays. Long fluorescence time, large Stokes shift, and minute fading out of the fluorescence over years are major advantages of the lanthanides over the conventional fluorescent dyes. We have now applied time-resolved fluorescence imaging (TRFI) also for measurement of type 1 diabetes mellitus (T1DM)-related islet cell autoantibodies (ICA). Retaining the accuracy of conventional ICA, TRFI has over 10 times better signal-to-noise ratio than the conventional fluorochromes. The technology allows objective determination of fluorescence intensity with the camera and computer software, and serial dilutions for obtaining the antibody titer in autoantibody-positive samples are unnecessary. We now describe the TRFI as a method and its application for measurement of ICA.

Geographical variation in risk HLA-DQB1 genotypes for type 1 diabetes and signs of beta-cell autoimmunity in a high-incidence country.

OBJECTIVE: To assess possible differences in the frequency of HLA-DQB1 risk genotypes and the emergence of signs of beta-cell autoimmunity among three geographical regions in Finland. RESEARCH DESIGN AND METHODS: The series comprised 4,642 children with increased HLA-DQB1-defined genetic risk of type 1 diabetes from the Diabetes Prediction and Prevention (DIPP) study: 1,793 (38.6%) born in Turku, 1,646 (35.5%) in Oulu, and 1,203 (25.9%) in Tampere. These children were examined frequently for the emergence of signs of beta-cell autoimmunity, for the primary screening of which islet cell antibodies (ICA) were used. If the child developed ICA, all samples were also analyzed for insulin autoantibodies (IAA), GAD65 antibodies (GADA), and antibodies to the IA-2 molecule (IA-2A). RESULTS: The high- and moderate-risk genotypes were unevenly distributed among the three areas (P<0.001); the high-risk genotype was less frequent in the Oulu region (20.4%) than in the Turku (28.4%; P<0.001) or Tampere regions (27.2%; P<0.001). This genotype was associated with an increased frequency of ICA seroconversion relative to the moderate risk genotypes (hazard ratio 1.89, 95% CI 1.36-2.62). Seroconversions to ICA positivity occurred less commonly in Tampere than in Turku (0.47, 0.28-0.75), whereas the seroconversion rate in Oulu did not differ from that in Turku (0.72, 0.51-1.03). The Tampere-Turku difference persisted after adjustment for risk genotypes, sex, and time of birth (before January 1998 versus later). Seroconversion for at least one additional autoantibody was also less frequent in Tampere than in Turku (0.39, 0.16-0.82). CONCLUSIONS: These data show that in Finland, the country with the highest incidence of type 1 diabetes in the world, both the frequency of the high-risk HLA-DQB1 genotype and the risk of seroconversion to autoantibody positivity show geographical variation. The difference in seroconversion rate could not be explained by the difference in HLA-DQB1-defined disease susceptibility, implying that the impact of environmental triggers of diabetes-associated autoimmunity may differ between the three regions studied.

Cord serum lipidome in prediction of islet autoimmunity and type 1 diabetes.

Previous studies show that children who later progress to type 1 diabetes (T1D) have decreased preautoimmune concentrations of multiple phospholipids as compared with nonprogressors. It is still unclear whether these changes associate with development of ß-cell autoimmunity or specifically with clinical T1D. Here, we studied umbilical cord serum lipidome in infants who later developed T1D (N = 33); infants who developed three or four (N = 31) islet autoantibodies, two (N = 31) islet autoantibodies, or one (N = 48) islet autoantibody during the follow-up; and controls (N = 143) matched for sex, HLA-DQB1 genotype, city of birth, and period of birth. The analyses of serum molecular lipids were performed using the established lipidomics platform based on ultra-performance liquid chromatography coupled to mass spectrometry. We found that T1D progressors are characterized by a distinct cord blood lipidomic profile that includes reduced major choline-containing phospholipids, including sphingomyelins and phosphatidylcholines. A molecular signature was developed comprising seven lipids that predicted high risk for progression to T1D with an odds ratio of 5.94 (95% CI, 1.07-17.50). Reduction in choline-containing phospholipids in cord blood therefore is specifically associated with progression to T1D but not with development of ß-cell autoimmunity in general.

Age at development of type 1 diabetes- and celiac disease-associated antibodies and clinical disease in genetically susceptible children observed from birth.

OBJECTIVE: To compare the ages and sequence in which antibodies associated with type 1 diabetes and celiac disease appear and overt diseases develop in children with an HLA-conferred susceptibility to both diseases. RESEARCH DESIGN AND METHODS: We observed 2,052 children carrying genetic risks for both type 1 diabetes and celiac disease from birth until the median age of 5.7 years and analyzed diabetes- and celiac disease-associated antibodies in serum samples collected at 3- to 12-month intervals. Diabetes was confirmed by World Health Organization criteria and celiac disease by duodenal biopsies. RESULTS: Altogether 342 children seroconverted to positivity for at least one diabetes-associated autoantibody and 88 to positivity for at least one celiac disease-associated antibody at the median ages of 3.0 and 1.5 years, respectively (P < 0.001). If only children with biochemically defined diabetes-associated autoantibodies against insulin, GAD, or IA-2A protein (n = 146) and children with tissue transglutaminase autoantibodies were compared (n = 86), the median seroconversion ages were 2.5 and 3.0 years (P = 0.011). Fifty-one children progressed to overt diabetes at 4.5 years and 44 children to celiac disease at 4.3 years (P = 0.257). Of the 19 children who developed both diabetes- and celiac disease-associated antibodies, 3 progressed to both diabetes and celiac disease. CONCLUSIONS: Children with HLA-conferred susceptibility to type 1 diabetes and celiac disease develop celiac disease-associated antibodies mostly at a younger age or the same age at which they develop diabetes-associated autoantibodies. Clinical diabetes and celiac disease are commonly diagnosed at the same median age.

Predictive characteristics of diabetes-associated autoantibodies among children with HLA-conferred disease susceptibility in the general population.

OBJECTIVE: As data on the predictive characteristics of diabetes-associated autoantibodies for type 1 diabetes in the general population are scarce, we assessed the predictive performance of islet cell autoantibodies (ICAs) in combination with autoantibodies against insulin (IAAs), autoantibodies against GAD, and/or islet antigen 2 for type 1 diabetes in children with HLA-defined disease predisposition recruited from the general population. RESEARCH DESIGN AND METHODS: We observed 7,410 children from birth (median 9.2 years) for beta-cell autoimmunity and diabetes. If a child developed ICA positivity or diabetes, the three other antibodies were measured in all samples available from that individual. Persistent autoantibody positivity was defined as continued positivity in at least two sequential samples including the last available sample. RESULTS: Pre-diabetic ICA positivity was observed in 1,173 subjects (15.8%), 155 of whom developed type 1 diabetes. With ICA screening, 86% of 180 progressors (median age at diagnosis 5.0 years) were identified. Positivity for four antibodies was associated with the highest disease sensitivity (54.4%) and negative predictive values (98.3%) and the lowest negative likelihood ratio (0.5). The combination of persistent ICA and IAA positivity resulted in the highest positive predictive value (91.7%), positive likelihood ratio (441.8), cumulative disease risk (100%), and specificity (100%). Young age at seroconversion, high ICA level, multipositivity, and persistent positivity for IAA were significant risk markers for type 1 diabetes. CONCLUSIONS: Within the general population, the combination of HLA and autoantibody screening resulted in disease risks that are likely to be as high as those reported among autoantibody-positive siblings of children with type 1 diabetes.

Dysregulation of lipid and amino acid metabolism precedes islet autoimmunity in children who later progress to type 1 diabetes.

The risk determinants of type 1 diabetes, initiators of autoimmune response, mechanisms regulating progress toward beta cell failure, and factors determining time of presentation of clinical diabetes are poorly understood. We investigated changes in the serum metabolome prospectively in children who later progressed to type 1 diabetes. Serum metabolite profiles were compared between sample series drawn from 56 children who progressed to type 1 diabetes and 73 controls who remained nondiabetic and permanently autoantibody negative. Individuals who developed diabetes had reduced serum levels of succinic acid and phosphatidylcholine (PC) at birth, reduced levels of triglycerides and antioxidant ether phospholipids throughout the follow up, and increased levels of proinflammatory lysoPCs several months before seroconversion to autoantibody positivity. The lipid changes were not attributable to HLA-associated genetic risk. The appearance of insulin and glutamic acid decarboxylase autoantibodies was preceded by diminished ketoleucine and elevated glutamic acid. The metabolic profile was partially normalized after the seroconversion. Autoimmunity may thus be a relatively late response to the early metabolic disturbances. Recognition of these preautoimmune alterations may aid in studies of disease pathogenesis and may open a time window for novel type 1 diabetes prevention strategies.

Fate of five celiac disease-associated antibodies during normal diet in genetically at-risk children observed from birth in a natural history study.

OBJECTIVES: To explore the natural history of antibodies against tissue transglutaminase (TGA), endomysium (EMA), reticulin (ARA), and gliadin (AGA-IgG and AGA-IgA) in children carrying HLA-conferred risk for celiac disease (CD) and observed frequently from birth. METHODS: TGA was measured in serum samples obtained between years 2000 and 2003 from 1,320 children carrying genetic CD risk. If a sample was TGA positive, all five antibodies were analyzed in all banked and forthcoming samples from that child, and a duodenal biopsy was recommended. At the end of this observation, in August 2004, the age of the children was from 1 to 9.5 yr (mean 4.1 yr). RESULTS: Forty-nine children (3.7%) were TGA positive. In these children, AGA-IgG had emerged at the mean age (+/- SD, range) of 2.0 +/- 1.5, 0.5-6.6 yr, while TGA, EMA, and ARA all emerged concurrently somewhat later (TGA at 3.2 +/- 1.5, 1.0-7.0 yr, P < 0.001 when compared to AGA-IgG). Despite continuing gluten exposure, positive TGA, EMA, ARA, AGA-IgA, and AGA-IgG values were spontaneously lost in 49%, 45%, 43%, 41%, and 32% of the children, respectively. CD was diagnosed by biopsy in 20 of the 26 TGA-positive children who consented to a biopsy. CONCLUSIONS: Potential CD trigger(s) other than only gluten probably function before AGA-IgG emerges, i.e., > or =3 months earlier than the transglutaminase-associated antibodies appear. In a remarkable proportion of the children, antibodies disappear spontaneously suggesting that regulatory immune phenomena under favorable circumstances are able to extinguish incipient CD in genetically at-risk children even without exclusion of gluten from the diet.

Natural history of transglutaminase autoantibodies and mucosal changes in children carrying HLA-conferred celiac disease susceptibility.

OBJECTIVE: The natural history of the appearance and fate of transglutaminase autoantibodies (TGAs) and mucosal changes in children carrying HLA-conferred celiac disease (CD) risk remains obscure. The aim of this study was to investigate the sequence of events leading to overt CD by retrospective analysis of TGA values in serum samples collected frequently from genetically susceptible children since birth or early childhood. MATERIAL AND METHODS: A total of 1101 at-risk children were recruited in the study. A duodenal biopsy was recommended to all TGA-positive children and performed if parental consent was obtained. RESULTS: During up to 8 years of follow-up, 35 of the cohort children developed TGAs, the youngest at age 1.3 years. After age 1.3 years the annual TGA seroconversion rate was constantly around 1% at least until age 6 years. However, 18 of the 35 TGA-positive children (51%) lost TGAs, without any dietary manipulation. A further 7 children were IgA deficient; of these children, 2 developed IgG antigliadin antibodies (IgG-AGA). Only 13 of the 21 children (62%) who had duodenal biopsies had villous atrophy. The time that passed since emergence of TGAs failed to predict the biopsy findings. Only one of the children with TGAs and both of the IgA-deficient children with IgG-AGA had noticeable abdominal symptoms. CONCLUSIONS: TGAs appear in children at a constant rate after 1 year of age until at least the age of 6 years. Over half of the children loose TGA without gluten exclusion, challenging TGA positivity-based CD prevalence estimates. In symptom-free children, a requirement of two consecutive TGA-positive samples taken >or=3 months apart before performing a duodenal biopsy might diminish the number of unnecessary intestinal biopsies.

Insulin autoantibody isotypes during the prediabetic process in young children with increased genetic risk of type 1 diabetes.

This work aimed to assess the maturation of the humoral immune response to insulin in preclinical type 1 diabetes by observing the emergence of various isotypes of insulin autoantibodies (IAA) in children with HLA-DQB1-conferred disease susceptibility. The series was derived from the Finnish Type 1 Diabetes Prediction and Prevention Study and comprised 15 IAA-positive children who presented with type 1 diabetes during prospective observation (progressors) and 30 children who remained nondiabetic (nonprogressors). An isotype-specific radiobinding assay was used to determine isotype-specific IAA (IgG1-4 and IgA) from samples obtained with an interval of 3-12 mo. The progressors had IAA of subclass IgG3 in their first IAA-positive sample more often than did the nonprogressors (13 of 15 versus 12 of 30; p = 0.003). Nine progressors had a dominant IgG1-IAA response initially, and six had a dominant IgG3-IAA response. The corresponding distribution among the nonprogressors was that 20 had a dominant IgG1-IAA response, none had an IgG3-IAA response, and three had a dominant response other than IgG1- or IgG3-IAA (chi(2)(df = 2) = 12.02; p = 0.002). The progressors had higher integrated levels (area under the curve) of IgG1-IAA (p = 0.05) and IgG3-IAA (p = 0.002). Nine progressors had a dominant integrated IgG1-IAA response and six had a dominant IgG3-IAA response over the observation period, whereas 22 nonprogressors had a dominant IgG1-IAA response, six had a dominant IgG2-IAA response, and one an IgG3-IAA response (chi(2)(df = 2) = 11.23; p = 0.004). Genetically susceptible young children who progress rapidly to clinical type 1 diabetes are characterized by strong IgG1 and IgG3 responses to insulin, whereas a weak or absent IgG3 response is associated with relative protection from disease.