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Genes in the HLA class II region include the most important inherited risk factors for type 1 diabetes (T1D) although also polymorphisms outside the HLA region modulate the predisposition to T1D. This study set out to confirm a recent observation in which a novel expression quantitative trait locus was formed by three single nucleotide polymorphisms (SNP) in the intron of HLA-DRA1 in DR3-DQ2 haplotypes. The SNPs significantly increased the risk for T1D in DR3-DQ2 homozygous individuals and we intended to further explore this association, in the Finnish population, by comparing two DR3-DQ2 positive genotypes. Cohorts with DR3-DQ2/DR3-DQ2 (N = 570) and DR3-DQ2/DR1-DQ5 (N = 1035) genotypes were studied using TaqMan analysis that typed for rs3135394, rs9268645 and rs3129877. The tri-SNP haplotype was significantly more common in cases than controls in the DR3-DQ2/DR3-DQ2 cohort (OR = 1.70 CI 95% = 1.15-2.51P = 0.007). However, no significant associations could be observed in the DR3-DQ2/DR1-DQ5 cohort. (c) 2021 The Authors. Published by Elsevier Inc. on behalf of American Society for Histocompatibility and Immunogenetics. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/).

Background Genetic heterogeneity in type I interferon (IFN)–related gene IFI44L may account for variable susceptibility to respiratory tract infections (RTIs) in children. Methods In 2 prospective, population-based birth cohorts, the STEPS Study and the FinnBrain Birth Cohort Study, IFI44L genotypes for rs273259 and rs1333969 were determined in relation to the development of RTIs until 1 or 2 years of age, respectively. At age 3 months, whole-blood transcriptional profiles were analyzed and nasal samples were tested for respiratory viruses in a subset of children. Results In the STEPS Study (n = 1135), IFI44L minor/minor gene variants were associated with lower rates of acute otitis media episodes (adjusted incidence rate ratio, 0.77 [95% confidence interval, .61–.96] for rs273259 and 0.74 [.55–.99] for rs1333969) and courses of antibiotics for RTIs (0.76 [.62–.95] and 0.73 [.56–.97], respectively. In the FinnBrain cohort (n = 971), IFI44L variants were associated with lower rates of RTIs and courses of antibiotics for RTIs. In respiratory virus–positive 3-month-old children, IFI44L gene variants were associated with decreased expression levels of IFI44L and several other IFN-related genes. Conclusions Variant forms of IFI44L gene were protective against early-childhood RTIs or acute otitis media, and they attenuated IFN pathway activation by respiratory viruses.

Blood myxovirus resistance protein A (MxA) has broad antiviral activity, and it is a potential biomarker for symptomatic virus infections. Limited data is available of MxA in coinciding viral and bacterial infections. We investigated blood MxA levels in children hospitalized with a febrile urinary tract infection (UTI) with or without simultaneous respiratory virus infection. We conducted a prospective observational study of 43 children hospitalized with febrile UTI. Nasopharyngeal swab samples were collected at admission and tested for 16 respiratory viruses by nucleic acid detection methods. Respiratory symptoms were recorded, and blood MxA levels were determined. The median age of study children was 4 months (interquartile range, 2–14 months). A respiratory virus was detected in 17 (40%) children with febrile UTI. Of the virus-positive children with febrile UTI, 7 (41%) had simultaneous respiratory symptoms. Blood MxA levels were higher in virus-positive children with respiratory symptoms (median, 778 [interquartile range, 535–2538] μg/L) compared to either virus-negative (155 [94–301] μg/L, P P = 0.006) children without respiratory symptoms at presentation with febrile UTI. MxA differentiated virus-positive children with respiratory symptoms from virus-negative without symptoms by an area under the receiver operating characteristic curve of 0.96. Respiratory viruses were frequently detected in children with febrile UTI. In UTI with simultaneous respiratory symptoms, host antiviral immune response was demonstrated by elevated blood MxA protein levels. MxA protein could be a robust biomarker of symptomatic viral infection in children with febrile UTI.

Validation and standardization of accurate serological assays are crucial for the surveillance of the coronavirus disease 2019 (COVID-19) pandemic and population immunity. We describe the analytical and clinical performance of an in-house fluorescent multiplex immunoassay (FMIA) for simultaneous quantification of antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleoprotein and spike glycoprotein. Furthermore, we calibrated IgG-FMIA against World Health Organization (WHO) International Standard and compared FMIA results to an in-house enzyme immunoassay (EIA) and a microneutralization test (MNT). We also compared the MNT results of two laboratories. IgG-FMIA displayed 100% specificity and sensitivity for samples collected 13 to 150 days post-onset of symptoms (DPO). For IgA- and IgM-FMIA, 100% specificity and sensitivity were obtained for a shorter time window (13 to 36 and 13 to 28 DPO for IgA- and IgM-FMIA, respectively). FMIA and EIA results displayed moderate to strong correlation, but FMIA was overall more specific and sensitive. IgG-FMIA identified 100% of samples with neutralizing antibodies (NAbs). Anti-spike IgG concentrations correlated strongly (r = 0.77 to 0.84, P < 2.2 x 10(-16)) with NAb titers, and the two laboratories' NAb titers displayed a very strong correlation (r = 0.95, P< 2.2 x 10(-16)). Our results indicate good correlation and concordance of antibody concentrations measured with different types of in-house SARS-CoV-2 antibody assays. Calibration against the WHO international standard did not, however, improve the comparability of FMIA and EIA results. IMPORTANCE SARS-CoV-2 serological assays with excellent clinical performance are essential for reliable estimation of the persistence of immunity after infection or vaccination. In this paper we present a thoroughly validated SARS-CoV-2 serological assay with excellent clinical performance and good comparability to neutralizing antibody titers. Neutralization tests are still considered the gold standard for SARS-CoV-2 serological assays, but our assay can identify samples with neutralizing antibodies with 100% sensitivity and 96% specificity without the need for laborious and slow biosafety level 3 (BSL-3) facility-requiring analyses.

BackgroundValidation and standardization of accurate serological assays are crucial for the surveillance of the coronavirus disease 2019 (COVID-19) pandemic and population immunity.MethodsWe describe the analytical and clinical performance of an in-house fluorescent multiplex immunoassay (FMIA) for simultaneous quantification of antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleoprotein and spike glycoprotein. Furthermore, we calibrated IgG-FMIA against World Health Organisation (WHO) International Standard and compared FMIA results to an in-house enzyme immunoassay (EIA) and a microneutralisation test (MNT). We also compared the MNT results of two laboratories.ResultsIgG-FMIA displayed 100% specificity and sensitivity for samples collected 13-150 days post-onset of symptoms (DPO). For IgA- and IgM-FMIA 100% specificity and sensitivity were obtained for a shorter time window (13-36 and 13-28 DPO for IgA- and IgM-FMIA, respectively). FMIA and EIA results displayed moderate to strong correlation, but FMIA was overall more specific and sensitive. IgG-FMIA identified 100% of samples with neutralising antibodies (NAbs). Anti-spike IgG concentrations correlated strongly (ρ=0.77-0.84, P−16) with NAb titers. The NAb titers of the two laboratories displayed a very strong correlation (ρ=0.95, P−16).DiscussionOur results indicate good correlation and concordance of antibody concentrations measured with different types of in-house SARS-CoV-2 antibody assays. Calibration against WHO international standard did not, however, improve the comparability of FMIA and EIA results.

Context Characterization of slow progression to type 1 diabetes (T1D) may reveal novel means for prevention of T1D. Slow progressors might carry natural immunomodulators that delay β-cell destruction and mediate preservation of β-cell function. Objective To identify demographic, genetic, and immunological characteristics of slow progression from seroconversion to clinical T1D. Design HLA-susceptible children (n = 7410) were observed from birth for islet cell antibody (ICA), insulin autoantibody (IAA), glutamic acid decarboxylase (GADA), and islet antigen-2 autoantibodies (IA-2A), and for clinical T1D. Disease progression that lasted ≥7.26 years (slowest) quartile from initial seroconversion to diagnosis was considered slow. Autoantibody and genetic characteristics including 45 non-HLA single nucleotide polymorphisms (SNPs) predisposing to T1D were analyzed. Results By the end of 2015, 1528 children (21%) had tested autoantibody positive and 247 (16%) had progressed to T1D. The median delay from seroconversion to diagnosis was 8.7 years in slow (n = 62, 25%) and 3.0 years in other progressors. Compared with other progressors, slow progressors were less often multipositive, had lower ICA and IAA titers, and lower frequency of IA-2A at seroconversion. Slow progressors were born more frequently in the fall, whereas other progressors were born more often in the spring. Compared with multipositive nonprogressors, slow progressors were younger, had higher ICA titers, and higher frequency of IAA and multiple autoantibodies at seroconversion. We found no differences in the distributions of non-HLA SNPs between progressors. Conclusions We observed differences in autoantibody characteristics and the season of birth among progressors, but no characteristics present at seroconversion that were specifically predictive for slow progression.

Context Children with initial autoantibodies to either insulin (IAA) or glutamic acid decarboxylase (GADA) differ in peak age of seroconversion and have different type 1 diabetes (T1D) risk gene associations, suggesting heterogeneity in the disease process. Objective To compare the associations of age at seroconversion, HLA risk, and specificity of secondary autoantibodies with the progression of islet autoimmunity between children with either IAA or GADA as their first autoantibody. Design and methods A cohort of 15,253 children with HLA-associated increased risk of T1D participated in a follow-up program in which islet autoantibodies were regularly measured. The median follow-up time was 6.7 years. Spearman correlation, Kaplan-Meier survival plots, and Cox proportional-hazard models were used for statistical analyses. Results Persistent positivity for at least one of the tested autoantibodies was detected in 998 children; 388 of children progressed to clinical T1D. Young age at initial seroconversion was associated with a high probability of expansion of IAA-initiated autoimmunity and progression to clinical diabetes, whereas expansion of GADA-initiated autoimmunity and progression to diabetes were not dependent on initial seroconversion age. The strength of HLA risk affected the progression of both IAA- and GADA-initiated autoimmunity. The simultaneous appearance of two other autoantibodies increased the rate of progression to diabetes compared with that of a single secondary autoantibody among subjects with GADA-initiated autoimmunity but not among those with IAA as the first autoantibody. Conclusions Findings emphasize the differences in the course of islet autoimmunity initiated by either IAA or GADA supporting heterogeneity in the pathogenic process.

Objective We aimed to clarify the association of various HLA risk alleles with different types of autoantibodies initiating islet specific autoimmunity. Methods Follow-up cohorts from the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study and children diagnosed with type 1 diabetes from the Finnish Pediatric Diabetes Register (FPDR) were analyzed for the presence of autoantibodies to insulin (IAA), glutamic acid decarboxylase (GADA), IA-2 antigen (IA-2A) and zinc transporter 8 (ZnT8A) and genotyped for HLA DR/DQ alleles. In the DIPP study autoantibodies were regularly analyzed from birth up to 15 years of age. Results In the DIPP cohort 621 children developed one single persistent autoantibody, GADA in 284, IAA in 268 and IA-2A in 40 cases. Highly significant differences in the specificity of the first autoantibody were observed between HLA genotypes. Homozygotes for the DR3-DQ2 haplotype had almost exclusively GADA as the first autoantibody whereas a more even distribution between GADA and IAA was found in DR3-DQ2/DR4-DQ8 as well as DR3-DQ/x and DR4-DQ8/x genotypes (x referring to neutral haplotypes). In DR4-DQ8 positive genotypes with the DRB1*04:01 allele IAA was more often the first autoantibody than in DRB1*04:04 positive genotypes. Various neutral haplotypes also significantly affected the relative proportions of different initial autoantibodies. These findings were confirmed and expanded in a series of 1591 T1D children under the age of 10 years from FPDR. Conclusions These results emphasize the importance of HLA class II polymorphisms in the recognition of autoantigen epitopes in the initiation of various pathways of the autoimmune response. This article is protected by copyright. All rights reserved.

Aims/Hypothesis: Evidence of the role of cytomegalovirus (CMV) infection in the pathogenesis of type 1 diabetes (T1D) has remained inconclusive. Our aim was to elucidate the possible role of CMV infection in the initiation of islet autoimmunity and in the progression to clinical T1D among children with human leukocyte antigen (HLA)‐conferred T1D risk. Methods: A total of 1402 children from the prospective Type 1 Diabetes Prediction and Prevention (DIPP) study were analyzed for CMV‐specific IgG antibodies during early childhood. All the children carried HLA‐DQ genotypes associated with increased risk for T1D. The effect of CMV infection on the appearance of T1D‐associated autoantibodies (insulin autoantibodies [IAA], glutamic acid decarboxylase [GADA], and insulinoma antigen‐2 [IA‐2A], n = 356) and on the progression rate to clinical T1D (n = 233) were analyzed with Kaplan‐Meier survival analysis and Log‐rank test. Results: Early childhood CMV infection was inversely associated with the development of T1D during childhood. Cumulative progression to T1D was decreased in subjects with an early CMV infection (P = 0.035). In further analyses, the effect of early CMV infection on the initiation of islet autoimmunity and progression to clinical T1D were examined separately. Interestingly, early CMV infection did not affect the appearance of T1D‐associated autoantibodies but a decelerating effect was observed on the progression rate from islet autoimmunity to clinical T1D (P = 0.015). Conclusion: Our results suggest that an early childhood CMV infection may decelerate the progression from islet autoimmunity to clinical T1D among at‐risk children and may thus protect these children from progressing to T1D during childhood.

Summary Objectives Besides group A streptococcus (GAS), microbial causes of pharyngitis in children are not well known. We aimed to document the viral and bacterial aetiology of pharyngitis and to assess the pathogenic role of viruses by determining the myxovirus resistance protein A (MxA) in the blood as a marker of interferon response. Methods In this prospective observational study, throat swabs and blood samples were collected from children (age 1–16 years) presenting to the emergency department with febrile pharyngitis. Microbial cause was sought by bacterial culture, polymerase chain reaction, and serology. Blood MxA level was determined. Results A potential pathogen was detected in 88% of 83 patients: GAS alone in 10%, GAS and viruses in 13%, group C or G streptococci alone in 2% and together with viruses in 3%, and viruses alone in 59% of cases. Enteroviruses, rhinoviruses, and adenoviruses were the most frequently detected viruses. Blood MxA levels were higher in children with viral (880 [245–1250] μg/L; median [IQR]) or concomitant GAS-viral (340 [150–710] μg/L) than in those with sole GAS (105 [80–160] μg/L) infections. Conclusions Detection of respiratory viruses simultaneously with elevated blood MxA levels supports the causative role of viruses in the majority of children with pharyngitis., Highlights • We evaluated the microbiological aetiology of febrile pharyngitis in 83 children. • A potential pathogen could be detected in 88% and virus in 76% of patients. • Blood myxovirus resistance protein A (MxA) levels were elevated in most of the patients with virus finding. • MxA is a promising biomarker of virus infection.

Dysfunction of FOXP3-positive regulatory T cells (Tregs) likely plays a major role in the pathogenesis of multiple autoimmune diseases including type 1 diabetes (T1D). Whether genetic polymorphisms associated with the risk of autoimmune diseases affect Treg frequency or function is currently unclear. Here, we analysed the effect of T1D-associated major HLA class II haplotypes and seven single nucleotide polymorphisms in six non-HLA genes [INS (rs689), PTPN22 (rs2476601), IL2RA (rs12722495 and rs2104286), PTPN2 (rs45450798), CTLA4 (rs3087243), and ERBB3 (rs2292239)] on peripheral blood Treg frequencies. These were determined by flow cytometry in 65 subjects who had progressed to T1D, 86 islet autoantibody-positive at-risk subjects, and 215 islet autoantibody-negative healthy controls. The PTPN22 rs2476601 risk allele A was associated with an increase in total (p = 6 × 10-6 ) and naive (p = 4 × 10-5 ) CD4+CD25+CD127lowFOXP3+ Treg frequencies. These findings were validated in a separate cohort comprising ten trios of healthy islet autoantibody-negative children carrying each of the three PTPN22 rs2476601 genotypes AA, AG, and GG (p = 0.005 for total and p = 0.03 for naive Tregs, respectively). In conclusion, our analysis implicates the autoimmune PTPN22 rs2476601 risk allele A in controlling the frequency of Tregs in human peripheral blood.

A declining first-phase insulin response (FPIR) is associated with positivity for multiple islet autoantibodies, irrespective of class II HLA DR-DQ genotype. We examined the associations of FPIR with genetic variants outside the HLA DR-DQ region in the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study in children with and without multiple autoantibodies. Association between FPIR and class I alleles A*24 and B*39 and eight single nucleotide polymorphisms outside the HLA region were analyzed in 438 children who had one or more FPIR results available after seroconversion. Hierarchical linear mixed models were used to analyze repeated measurements of FPIR. In children with multiple autoantibodies, the change in FPIR over time was significantly different between those with various PTPN2 (rs45450798), FUT2 (rs601338), CTSH (rs3825932), and IKZF4 (rs1701704) genotypes in at least one of the models. In general, children carrying susceptibility alleles for type 1 diabetes experienced a more rapid decline in insulin secretion compared with children without susceptibility alleles. The presence of the class I HLA A*24 allele was also associated with a steeper decline of FPIR over time in children with multiple autoantibodies. Certain genetic variants outside the class II HLA region may have a significant impact on the longitudinal pattern of FPIR.

Objective The HLA-DR/DQ region remains the major determinant of susceptibility to type 1 diabetes (T1D) despite the more than 50 risk affecting loci outside human leukocyte antigen (HLA) region that have been identified. We aimed at developing a simple risk estimation based on HLA class II genotyping, which was also tested by analyzing HLA class II effect on the autoantibody seroconversion and further progression to diabetes. Subjects and methods A total of 2991 trio families with a diabetic child from the Finnish Pediatric Diabetes Register were genotyped and the risk contributed by each DR-DQ haplotype calculated through transmission analysis. The genotype risk was estimated based on the summary effect of haplotypes. Genotype grouping was further tested in a subcohort of the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study Results The summary effect of haplotypes was generally seen in genotypes, while the expected synergistic effect of DR3-DQ2 and DR4-DQ8 (DRB1*04:03 excluded) combination was also clear in the T1D risk association analysis. This highest risk DR/DQ genotype was found in 21.6% of patients and 2.0% of controls, odds ratio (OR) = 13.2 (10.1–17.2), whereas the lowest risk genotype contained only 0.8% of patients and 28.0% of controls, OR = 0.02 (0.01–0.03). In the subcohort from the DIPP study the risk grades correlated clearly with seroconversion for islet autoantibodies and T1D development. In contrast, DR/DQ risk groups did not associate with the progression rate from advanced autoimmunity to clinical diabetes. Conclusions Class II HLA genotype groups improve the estimation of T1D risk. Class II effect is limited to the early phase of the disease process characterized by seroconversion for islet autoantibodies.

Objective The relationship between patterns of islet autoantibodies at diagnosis and specificity of the first islet autoantibody at the initiation of autoimmunity was analyzed with the aim of identifying patterns informative of the primary autoantibodies. Methods Information about a single first autoantibody at seroconversion and autoantibody data at diagnosis were available for 128 children participating in the follow-up cohort of the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study. Autoantibody data at diagnosis and genotyping results were also obtained from children in the Finnish Pediatric Diabetes Register (FPDR). Results Insulin autoantibodies (IAA) were the most common primary antibodies (N = 68), followed by those for glutamic acid decarboxylase (GADA; N = 38), IA-2 antigen (IA-2A; N = 13), and zinc transporter 8 (ZnT8A; N = 9), whereas at diagnosis, IA-2A were most frequent (N = 103), followed by IAA (N = 78), ZnT8A (N = 73), and GADA (N = 71). Accordingly, the presence of many specific autoantibodies at diagnosis was due to the secondary antibodies appearing after primary antibodies, and in some cases, the primary autoantibody, most often IAA, had already disappeared at the time of diagnosis. Many of the autoantibody combinations present at diagnosis could be assembled into groups associated with either IAA or GADA as first autoantibodies. These combinations, in children diagnosed below the age of 10 years in the FPDR, were found to be strongly associated with risk genotypes in either INS (IAA first) or IKZF4-ERBB3 (GADA first) genes. Conclusions Autoantibody patterns at diagnosis may be informative on primary autoantibodies initiating autoimmunity in young children developing type 1 diabetes.

We analyzed demographic and genetic differences between children with various diabetes-associated autoantibodies reflecting the autoimmune process. In a prospective birth cohort comprising children with HLA-conferred susceptibility to type 1 diabetes (T1D), the pattern of autoantibody appearance was analyzed in 520 children with advanced β-cell autoimmunity associated with high risk for disease. In 315 cases, a single biochemical autoantibody could be identified in the first positive sample as insulin (insulin autoantibody [IAA]) in 180, as GAD (GAD antibody [GADA]) in 107, and as IA-2 antigen (IA-2 antibody [IA-2A]) in 28. The age at seroconversion differed significantly between the three groups (P = 0.003). IAA as the first autoantibody showed a peak time of appearance during the second year of life, whereas GADA as the first autoantibody peaked later, between 3 and 5 years of age. The risk-associated insulin gene rs689 A/A genotypes were more frequent in children with IAA as the first autoantibody compared with the other children (P = 0.002). The primary autoantigen in the development of β-cell autoimmunity and T1D seems to strongly correlate with age and genetic factors, indicating heterogeneity in the initiation of the disease process.

Aims/hypothesis In this study, we aimed to characterise rapid progressors to type 1 diabetes among children recruited from the general population, on the basis of HLA-conferred disease susceptibility. Methods We monitored 7410 HLA-predisposed children participating in the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study for the development of beta cell autoimmunity and type 1 diabetes from birth over a median follow-up time of 16.2 years (range 0.9-21.1 years). Islet cell antibodies (ICA) and autoantibodies to insulin (IAA), GAD (GADA) and islet antigen 2 (IA-2A) were assessed as markers of beta cell autoimmunity. Rapid progression was defined as progression to clinical type 1 diabetes within 1.5 years of autoantibody seroconversion. We analysed the association between rapid progression and demographic and autoantibody characteristics as well as genetic markers, including 25 non-HLA SNPs predisposing to type 1 diabetes. Results Altogether, 1550 children (21%) tested positive for at least one diabetes-associated autoantibody in at least two samples, and 248 (16%) of seroconverters progressed to type 1 diabetes by the end of 2015. The median time from seroconversion to diagnosis was 0.51 years in rapid progressors (n = 42, 17%) and 5.4 years in slower progressors. Rapid progression was observed both among young ( 7 years), resulting in a double-peak distribution of seroconversion age. Compared with slower progressors, rapid progressors had a higher frequency of positivity for multiple (>= 2) autoantibodies and had higher titres of ICA, IAA and IA-2A at seroconversion, and there was a higher prevalence of the secretor genotype in the FUT2 gene among those carrying the high-risk HLA genotype. Compared with autoantibody-positive non-progressors, rapid progressors were younger, were more likely to carry the high-risk HLA genotype and a predisposing SNP in the PTPN22 gene, had higher frequency of ICA, IAA, GADA and IA-2A positivity and multipositivity, and had higher titres of all four autoantibodies at seroconversion. Conclusions/interpretation At seroconversion, individuals with rapid progression to type 1 diabetes were characterised by a younger age, higher autoantibody titres, positivity for multiple autoantibodies and higher prevalence of a FUT2 SNP. The double-peak profile for seroconversion age among the rapid progressors demonstrates for the first time that rapid progression may take place not only in young children but also in children in early puberty. Rapid progressors might benefit from careful clinical follow-up and early preventive measures.

We set out to analyze the role of two major non-HLA gene polymorphisms associated with type 1 diabetes (T1D), PTPN22 1858C/T and insulin gene INS−23 A/T in progression to clinical T1D after the appearance of β-cell autoimmunity. The study population comprised 249 children with HLA-associated T1D susceptibility. All subjects were persistently positive for at least one of the T1D-associated biochemically defined autoantibodies (insulin autoantibody, GAD antibody, or IA-2 antibody), and 136 subjects presented with T1D over a median follow-up of 4.3 years (range 0.0–12.5) after the appearance of the first autoantibody. The PTPN22 1858T allele was strongly associated with progression to T1D after the appearance of the first biochemically defined β-cell autoantibody (hazard ratio 1.68 [95% CI 1.09–2.60], P = 0.02 Cox regression analysis, multivariate test), and the effect remained similar when analyzed after the appearance of the second autoantibody (P = 0.013), whereas INS−23 HphI AA genotype was not associated with progression to clinical diabetes after the appearance of the first or second autoantibody (P = 0.38 and P = 0.88, respectively). The effect of the INS risk genotype seems to be limited to the induction and early phases of β-cell autoimmunity, but the PTPN22 1858T allele instead affects the initiation and late progression phase of diabetes-associated autoimmunity.

Background Enteral virus infections and early introduction of cow's milk (CM)-based formula are among the suggested triggers of type 1 diabetes (T1D)-associated autoimmunity, although studies on their role have remained contradictory. Here, we aimed to analyse whether interactions between these factors might clarify the controversies. Materials The study population comprised 107 subjects developing positivity for at least two T1D-associated autoantibodies and 446 control subjects from the Finnish diabetes prediction and prevention cohort. Enterovirus, rotavirus, adenovirus, respiratory syncytial virus and bovine insulin-binding antibodies were analysed from prospective serum samples at 3–24 months of age. Data on infant cow's milk exposure were available for 472 subjects: 251 subjects were exposed to cow's milk before 3 months of age and 221 subjects later in infancy. Results Signs of an enterovirus infection by 12 months of age were associated with the appearance of autoimmunity among children who were exposed to cow's milk before 3 months of age. Cox regression analysis revealed a combined effect of enterovirus infection and early cow's milk exposure for the development of ICA and any of the biochemically defined autoantibodies (p = 0.001), of IAA (p = 0.002), GADA (p = 0.001) and IA-2A (p = 0.013). Conclusions The effect of enterovirus infection on the appearance of T1D-associated autoimmunity seems to be modified by exposure to cow's milk in early infancy suggesting an interaction between these factors. Moreover, these results provide an explanation for the controversial findings obtained when analysing the effect of any single one of these factors on the appearance of T1D-associated autoimmunity. Copyright © 2011 John Wiley & Sons, Ltd.

OBJECTIVE Class II alleles define the main HLA effect on type 1 diabetes, but there is an independent effect of certain class I alleles. Class II and class I molecules are differently involved in the initiation and effector phases of the immune response, suggesting that class I alleles would be important determinants in the rate of β-cell destruction. To test this hypothesis we analyzed the role of HLA class I and class II gene polymorphisms in the progression from diabetes-associated autoimmunity to clinical disease. RESEARCH DESIGN AND METHODS The effect of HLA-DR-DQ haplotypes and a panel of class I HLA-A and -B alleles on the progression from autoantibody seroconversion to clinical diabetes was studied in 249 children persistently positive for at least one biochemical diabetes-associated autoantibody in addition to islet cell autoantibody. RESULTS The progression to clinical disease was separately analyzed after the appearance of the first and the second persistent biochemical autoantibody using Cox regression. Multivariate analysis demonstrated a significant protective effect of the A*03 allele (odds ratio [OR] 0.61, P = 0.042 after the first and OR 0.55, P = 0.027 after the second autoantibody), whereas the B*39 allele had a promoting effect after seroconversion for the second autoantibody (OR 2.4, P = 0.014). When children with the DR3/DR4 genotype were separately analyzed, HLA-B*39 had a strong effect (OR 6.6, P = 0.004 and OR 7.5, P = 0.007, after the appearance of the first and the second autoantibody, respectively). The protective effect of A*03 was seen only among children without the DR3/DR4 combination. CONCLUSIONS These results confirm that class I alleles affect the progression of diabetes-associated autoimmunity and demonstrate interactions between class I and class II alleles.

Genetic heterogeneity may affect the analysis of risk factors associated with type 1 diabetes (T1D). We studied the effect of the INS -23A/T, PTPN22 1858C/T, and CTLA-4 +49A/G polymorphisms on the emergence of T1D-associated autoimmunity in children exposed to cow's milk (CM) based formula during early or late infancy. The study comprised of 156 children from the Finnish DIPP cohort who had developed >or= 2 types of autoantibodies (ICA, IAA, GADA or IA-2A) or clinical T1D and 563 control children. The PTPN22 1858T allele was associated with the appearance of the autoantibodies and clinical T1D among children exposed to CM formula before the age of 6 months (PTPN22: for all P