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J Ilonen

Publications and source records attributed to J Ilonen.

At least 91 records · Page 5Linked to original sources
PubMed1999

Disease-associated autoantibodies and HLA-DQB1 genotypes in children with newly diagnosed insulin-dependent diabetes mellitus (IDDM). The Childhood Diabetes in Finland Study Group.

The possible relation between HLA-DQ genotypes and both frequencies and levels of autoantibodies associated with IDDM was assessed by examining HLA-DQB1 alleles and antibodies to islet cells (ICA), insulin (IAA), glutamic acid decarboxylase (GADA) and the protein tyrosine phosphatase-related IA-2 molecule (IA-2A) in 631 newly diagnosed diabetic children under the age of 15 years. ICA were found in 530 children (84.0%), while close to half of the subjects (n = 307; 48.7%) tested positive for IAA. GADA were detected in 461 index cases (73.1%), with a higher frequency in those older than 10 years (78.9% versus 69.2% in the younger ones; P = 0.006). More than 85% of the children (n = 541; 85.7%) tested positive for IA-2A. Altogether there were only 11 children (1.7%) who had no detectable autoantibodies at diagnosis. There were no differences in the prevalence of ICA or GADA between four groups formed according to their HLA-DQB1 genotype (DQB1*0302/02, *0302/X (X = other than *02), *02/Y (Y = other than *0302) and other DQB1 genotypes). The children with the *0302/X genotype had a higher frequency of IA-2A and IAA than those carrying the *02/Y genotype (93.8% versus 67.3%, P < 0.001; and 49.0% versus 33.6%, P = 0.002, respectively). The children with the *02/Y genotype had the highest GADA levels (median 36.2 relative units (RU) versus 14.9 RU in those with *0302/X; P = 0.005). Serum levels of IA-2A and IAA were increased among subjects carrying the *0302/X genotype (median 76.1 RU versus 1.6 RU, P = 0.001; and 50 nU/ml versus 36 nU/ml, P = 0.004) compared with those positive for *02/Y. Only three out of 11 subjects homozygous for *02 (27.3%) tested positive for IA-2A, and they had particularly low IA-2A (median 0.23 RU versus 47.6 RU in the other subjects; P < 0.001). The distribution of HLA-DQB1 genotypes among autoantibody-negative children was similar to that in the other patients. These results show that DQB1*0302, the most important single IDDM susceptibility allele, is associated with a strong antibody response to IA-2 and insulin, while GAD-specific humoral autoimmunity is linked to the *02 allele, in common with a series of other autoimmune diseases as well as IDDM. We suggest that IA-2A may represent beta cell-specific autoimmunity, while GADA may represent a propensity to general autoimmunity.

Adolescent↗
PubMed1999

Comparison of enterovirus-specific cellular immunity in two populations of young children vaccinated with inactivated or live poliovirus vaccines.

Enterovirus-specific cellular immunity was studied in Estonian and in Finnish children at the age of 9 months. The aim was to evaluate the level of responsiveness in two neighbouring countries with different poliovirus immunization practices and striking differences in the incidence of insulin-dependent diabetes mellitus (IDDM), a disease in which early enterovirus infections are an aetiological risk factor. The Estonian children immunized with live attenuated polio vaccine had stronger T cell responses to coxsackievirus B4 and poliovirus type 1 when compared with Finnish children immunized with inactivated polio vaccine (median stimulation indices 10.4 and 6.3 in Estonian children and 1.9 and 2.9 in Finnish children, respectively; P < 0.05). Lymphocytes stimulated by poliovirus type 1 antigen expressed interferon-gamma (IFN-gamma) mRNAs, which strongly correlated with the level of proliferation responses. Lymphocytes of Estonian children had a tendency towards stronger expression of IFN-gamma upon poliovirus challenge when compared with Finnish children. The number of children who had experienced coxsackievirus B infections, as determined by the presence of neutralizing antibodies, did not differ between Estonian and Finnish children. The results show that Finnish children have weaker cellular immunity against enteroviruses at the age of 9 months compared with Estonian children at the same age. This is most probably due to the difference in polio vaccination schedules; in Estonia live poliovirus vaccine is used and given at earlier ages than the inactivated vaccines in Finland. This leads to stronger T cell immunity which cross-reacts with other enterovirus serotypes. This may explain the lower incidence of IDDM in Estonia by providing effective protection against diabetogenic enterovirus strains in Estonian children.

Antibodies, Viral↗
PubMed1999

Population-based genetic screening for the estimation of Type 1 diabetes mellitus risk in Finland: selective genotyping of markers in the HLA-DQB1, HLA-DQA1 and HLA-DRB1 loci.

AIMS: To improve sensitivity and specificity of the diabetes risk assessment of the population-based genetic screening used in the Finnish Diabetes Prediction and Prevention (DIPP) trial. METHODS: One thousand consecutive newborns enrolled in the DIPP were compared with 316 samples from children with Type 1 diabetes mellitus. A modification of the previously described technique based on hybridization of relevant PCR products with five lanthanide-labelled probes detected by time-resolved fluorometry (TRF) was used. A new probe was designed and allowed discrimination between DQB1*0602 and 0603 alleles, in addition to DQB1*02, *0301 or *0302, each of which required specific probes. A new, added screening strategy was developed for individuals carrying low-risk genotypes through specific typing of DQA1 *05 and *0201 alleles in DQB1*02 positive, and DRB1 typing for DR4 subtypes in DQB1*0302 positive subjects, with a new specifically designed high-resolution TRF-based DR4 subtyping technique. RESULTS: This two-step screening approach enhanced the sensitivity of the detection of genetic risk for Type 1 diabetes mellitus in this cohort up to 85.4%. In the general population cohort, 24.4% were identified for prospective follow-up, 2.6% of these are expected to develop Type 1 diabetes mellitus before the age of 15 years. Exclusive typing for HLA-DQB1 locus as an alternative screening strategy had sensitivities of 26.3-77.2% with general population cohorts of 2.3-23.1% identified for follow-up. CONCLUSIONS: The described strategy for genetic prediction of Type 1 diabetes mellitus relies on the convenient genotyping procedure and could be applied in large scale screening projects such as DIPP.

Biomarkers↗
PubMed1999

Characterization of T cell epitopes in measles virus nucleoprotein.

T cell epitopes of the measles virus (MV) nucleoprotein were studied by synthesizing overlapping 20 aa peptides over the known sequence of the protein and analysing the proliferation responses of a panel of MV-specific T cell lines and clones against these peptides. T cell lines were established from eleven healthy controls and seven multiple sclerosis patients, all with a history of past MV infection. The epitopes recognized by these lines were concentrated in a few regions of the polypeptide chain. Overlapping peptides containing aa 321-340 and 331-350 were most often recognized. Other epitopes were detected close to the amino-terminal end of the polypeptide chain as each of the peptides 1-20, 21-40, 31-50 and 51-70 contained stimulating moieties. Some responses were also detected towards peptides 151-200 and 221-250, but the carboxy-terminal end of the polypeptide was not recognized by any of the tested T cell lines. The amino acid sequences of the peptides that stimulated the T cell clones and lines, as a rule, contained binding motifs described for HLA-DR alleles found in T cell donors. The regions of protein sequence which did not reveal any T cell epitopes were, instead, relatively free of binding motifs. The results suggest that only a few epitopes of the MV nucleoprotein are important in establishing T cell immunity.

Epitopes↗
PubMed1999

Cow's milk formula feeding induces primary immunization to insulin in infants at genetic risk for type 1 diabetes.

Insulin autoantibodies (IAAs) often appear as the first sign of islet cell autoimmunity in prediabetic children. Because cow's milk contains bovine insulin, we followed the development of insulin-binding antibodies in children fed with cow's milk formula. Bovine insulin- and human insulin-binding antibodies by enzyme immunoassay and IAA by radioimmunoassay were analyzed in 200 infants carrying HLA-DQB1*0302 but no protective alleles who participated in a Finnish population-based birth-cohort study. Based on the prospectively registered information, the first 100 infants enrolled in the study who were exposed to cow's milk formula before age 12 weeks and the first 100 infants enrolled in the study who were exclusively breast-fed for longer than their first 12 weeks of life were selected for the present study. Also, 11 children from the birth cohort who developed at least two diabetes-associated autoantibodies, 98 children with newly diagnosed type 1 diabetes, and 92 healthy children were studied. We found that the amount of IgG-antibodies binding to bovine insulin was higher at age 3 months in infants who were exposed to cow's milk formula than in infants who were exclusively breast-fed at that age (median 0.521 vs. 0.190; P < 0.0001). The antibodies binding to bovine insulin cross-reacted with human insulin. None of these infants tested positive for IAA. The levels of bovine insulin-binding antibodies declined in both groups at ages 12 and 18 months, whereas in the 11 children with at least two diabetes-associated autoantibodies the levels increased during the follow-up period (P < 0.0001). IgG antibodies correlated with IgG2 antibodies binding to bovine insulin (r = 0.43, P = 0.004) and IAA (r = 0.27, P = 0.02) in diabetic children, but not in healthy children. Cow's milk feeding is an environmental trigger of immunity to insulin in infancy that may explain the epidemiological link between the risk of type 1 diabetes and early exposure to cow's milk formulas. This immune response to insulin may later be diverted into autoaggressive immunity against beta-cells in some individuals, as indicated by our findings in children with diabetes-associated autoantibodies.

Antigen-Antibody Reactions↗
PubMed1999

Clinical, autoimmune, and genetic characteristics of very young children with type 1 diabetes. Childhood Diabetes in Finland (DiMe) Study Group.

OBJECTIVE: To study the characteristics of type 1 diabetes in very young children. RESEARCH DESIGN AND METHODS: Clinical outcome, islet cell antibodies (ICA), insulin autoantibodies (IAA), antibodies against GAD (GADA), IA-2 antibodies (IA-2A), and HLA-DQB1-defined genetic risk were analyzed in 35 children diagnosed with type 1 diabetes before 2 years of age and compared with those in 146 children who were diagnosed between 2.0 and 4.9 years of age and with those in 620 children diagnosed between 5.0 and 14.9 years of age. RESULTS: The youngest age-group had severer metabolic decompensation at clinical onset, and their serum C-peptide levels, compared with those of older children, were lower at the time of diagnosis and during the first 2 years after the diagnosis. The levels of ICA and IAA were highest in children < 2 years of age, but there were no differences in GADA levels among the three age-groups. The youngest age-group had the lowest IA-2A levels. The HLA DQB1*02/*0302 genotype associated with strong genetic susceptibility was more frequent in children diagnosed < 5 years of age, whereas the proportion of children carrying a genotype, which includes protective alleles, was higher among those diagnosed at > or = 5 years of age. CONCLUSIONS: The clinical presentation of type 1 diabetes at a very young age is associated with severe metabolic decompensation, poorly preserved residual beta-cell function, strong humoral autoimmunity against islet cells and insulin, and strong HLA-defined disease susceptibility.

Adolescent↗
PubMed1999

Production of the islet cell antigen ICA69 (p69) with baculovirus expression system: analysis with a solid-phase time-resolved fluorescence method of sera from patients with IDDM and rheumatoid arthritis.

Islet cell antigen 69 (ICA69), previously implicated as an autoantigen in autoimmune insulin-dependent diabetes mellitus (IDDM), was produced using baculovirus-mediated expression in Spodopterafrugiperda (Sf9) insect cells. In these cells the protein was effectively expressed and ICA69 carrying C-terminal histidine-hexapeptide could be efficiently purified using immobilized metal chelate affinity chromatography. Screening of patient and control sera using this protein as an antigen in time-resolved fluoroimmunoassay (TR-FIA) identified 4/50 of patients with IDDM and 6/73 of patients with rheumatoid arthritis (RA) to be positive for ICA69 antibodies. The number of positives did not differ significantly between patients and control subjects but the level of binding was higher in sera from RA patients compared to that of control sera (P = 0.003). The results show that some subjects have specific autoreactive antibodies against the ICA69 protein produced with recombinant technology.

Arthritis, Rheumatoid↗
PubMed1998

Detection of HLA-B27 alleles by group-specific amplification and time-resolved fluorometry.

This newly developed HLA-B27 assay combines a polymerase chain reaction (PCR) from blood spot samples with solution hybridisation in microtitration plate and with time-resolved fluorometry (TRF) as the detection system. In a multiplex amplification reaction, the 144 base pair region of HLA-B27 alleles is amplified with allele-specific primers simultaneously with the region of beta-actin gene as an internal control. Amplified products are collected onto streptavidin (SA)-coated microtitration wells, denatured and hybridised with a europium (Eu)-labelled HLA-B27 specific probe and a samarium (Sm)-labelled beta-actin specific probe. Finally, Eu and Sm fluorescence is enhanced and detected in a time-resolved fluorometer. The typing results obtained with 110 blood spot samples showed an exact match with serological class I HLA-typing. When this technique was further evaluated, 348 blood spot samples were clearly categorised into two populations, HLA-B27 positives and negatives. This new PCR-TRF method permits the automation of HLA-B27 assays and saves time and labour in routine diagnostics.

Alleles↗
PubMed1998

Enterovirus infections and enterovirus specific T-cell responses in infancy.

The development of enterovirus specific T-cell and antibody responses were examined in a cohort of 60 healthy infants at the ages of 3, 6, 9, and 12 months. By the age of 6 months, 68% of the infants had developed T-cell responses against enterovirus antigens by lymphocyte proliferation test, whereas only 30% had serological evidence of an enterovirus infection. By this age, only 7% of the infants had adenovirus specific T-cell responses and 3% had serologically verified adenovirus infection. Enterovirus specific T-cell responses correlated with the lack of enterovirus antibodies in cord blood and the number of sibs reflecting protection by maternal antibodies and the rate of exposures, respectively. T-cell responses cross-reacted between different enterovirus serotypes. The results show that enterovirus infections occur frequently in infancy and induce T-cell immunity. Cellular immunity may be a more sensitive indicator of neonatal enterovirus infections than antibodies.

Antibodies, Viral↗
PubMed1998

Significance of cow's milk protein antibodies as risk factor for childhood IDDM: interactions with dietary cow's milk intake and HLA-DQB1 genotype. Childhood Diabetes in Finland Study Group.

Dietary factors are suspected to play an aetiological role in the development of insulin-dependent diabetes mellitus (IDDM). We analysed cow's milk formula, betalactoglobulin, and bovine serum albumin antibodies by an enzyme-linked immunoassay in unselected children with newly diagnosed IDDM and in their non-diabetic siblings and inquired about infant feeding practices by questionnaire. Among 410 diabetic sibling pairs matched for age and sex, by logistic regression analysis - including overall duration of breast-feeding, age at introduction of dairy products, recent consumption of cow's milk and HLA-DQB1 genotype ("high/moderate" vs "low/decreased" risk of IDDM) - bovine serum albumin IgG antibody levels (OR 2.12, 95% CI 1.25-3.57) and genetic risk (OR 3.81, 95% CI 2.43-5.17) were positively associated with IDDM; cow's milk formula IgM antibodies were inversely associated with the risk of IDDM (OR 0.50, 95% CI 0.29-0.87). Of the diabetic sibling pairs, 42 were identical for HLA-DQB1 alleles associated with IDDM risk or protection (DQB1*0201, *0301, *0302 and *0602/03). In these 42 pairs, children with IDDM had higher median levels of bovine serum albumin IgG, of betalactoglobulin IgG, and of cow's milk formula IgG and IgA antibodies than the non-diabetic siblings (p < 0.05). In conclusion, children with IDDM have higher levels of cow's milk protein antibodies than their HLA-DQB1-matched sibling controls, and these high levels of antibodies are independent risk markers for IDDM.

Animals↗
PubMed1998

Costs of predicting IDDM.

Programmes aiming at prediction and prevention of insulin-dependent diabetes mellitus (IDDM), a multifactorial autoimmune disease, have been launched or are in the planning phase in several countries. We hypothesized that the costs of finding the correct target subjects for preventive interventions are likely to vary markedly according to the prediction strategy chosen. Average direct costs accruing in the Finnish IDDM Prediction and Prevention Project (DIPP) were analysed from the health care provider's viewpoint. The genetically targeted strategy included costs of assessing genetic IDDM susceptibility followed by measurement of marker(s) of islet autoimmunity in the susceptibility restricted population at 3 to 6-month intervals. In the pure immunological strategy markers of autoimmunity were repeatedly analysed in the entire population. The data were finally exposed to sensitivity analysis. The genetically targeted prediction strategy is cost-saving in the first year if autoimmune markers are analysed as frequently as under the DIPP project, and in all circumstances later. The 10-year direct costs per child are US$ 245 (present value $ 217, 5% discount rate) if the genetically targeted approach is used and $ 733 (present value $ 619) if the pure immunological strategy is chosen. In sensitivity analysis the 10-year costs (present value) per child of the genetically targeted strategy and of the pure immunological strategy varied from $ 152 to $ 241 and from $ 430 to $ 788, respectively. The genetically targeted IDDM prediction strategy is remarkably cost-saving as compared with the pure immunological strategy mainly because fewer subjects will need retesting during the follow-up.

Administration, Intranasal↗
PubMed1998

Autoantibodies associated with Type I diabetes mellitus persist after diagnosis in children.

To study the persistence of Type I (insulin-dependent) diabetes mellitus associated autoantibodies and their relation to genetic risk markers and clinical characteristics of the disease after clinical manifestation, serum samples were obtained from 90 children and adolescents at diagnosis and 2, 5 and 10 years later. The samples were analysed for islet cell antibodies (ICA) by immunofluorescence and for antibodies to glutamic acid decarboxylase (GADA), intracellular portion of the protein tyrosine phosphatase related IA-2 antigen (IA-2A) and insulin autoantibodies by specific radiobinding assays. Of the subjects tested 79% were positive for IA-2A at diagnosis, 62% for GADA, 81% for ICA and 28% for insulin autoantibodies, but the prevalence of IA-2A, GADA and ICA decreased substantially as a function of increasing duration of the disease (p < 0.05 or less), their levels following the same pattern (p < 0.001 for all three autoantibodies). Two thirds of the subjects still tested positive for at least one autoantibody specificity after the first 10 years of the disease and 42% had two or three antibodies detectable. An increase over the initial antibody concentrations after the diagnosis was seen more often for GADA than for ICA (p < 0.001) or IA-2A (p < 0.05). In conclusion, autoantibodies associated with Type I diabetes appear to persist longer than expected after manifestation of the clinical disease, possibly due to small scale continuous beta-cell regeneration after diagnosis or to structural and/or functional mimicry between exogenous proteins and beta-cell antigens or both.

Adolescent↗
PubMed1998

Autoimmune and clinical characteristics of type I diabetes in children with different genetic risk loads defined by HLA-DQB1 alleles. Childhood Diabetes in Finland Study Group.

1. The impact of different genetic risk loads defined by HLA-DQB1 alleles on the autoimmune and clinical characteristics of 647 children and adolescents with recent-onset Type I diabetes was evaluated in a prospective population-based study. The subjects were divided into four groups based on HLA-DQB1 genotypes: DQB1*0302/0201 (high risk), *0302/x (moderate risk), *0201/y (low risk) and *z/z (decreased risk). 2. Close to two thirds (62.3%) of the subjects possessed a high or moderate risk genotype. A decreased frequency of positivity for islet cell antibodies (ICA) and insulin autoantibodies (IAA) (76.8% compared with 85.3%; P = 0.05, and 30.5% compared with 50.8%, P = 0.0006, respectively) but not of positivity for antibodies to the 65 kDa isoform of glutamate decarboxylase was observed in children with the DQB1*0201/y genotype compared with other children. Among ICA-negative subjects, those with the DQB1*0201/y genotype had higher serum C-peptide levels over the first 2 years after the diagnosis of Type I diabetes than those with other genotypes (P = 0.028). 3. Our data provide some evidence of HLA-DQB1-determined heterogeneity in the autoimmune and clinical characteristics of childhood Type I diabetes at the time of the clinical manifestation. This suggests differences between children with various HLA-DQB1 genotypes in the pace and/or intensity of the beta-cell destructive process leading to clinical Type I diabetes.

Adolescent↗
PubMed1998

T-cell reactivity to wheat gluten in patients with insulin-dependent diabetes mellitus.

Dietary wheat gluten has been associated with the risk of diabetes in animal models of human insulin-dependent diabetes mellitus (IDDM). To evaluate the role of wheat gluten as a T cell antigen in human IDDM, we studied the cell-mediated immune response to wheat gluten in patients with IDDM and in control subjects. The cellular response to gluten was measured by the peripheral blood mononuclear cell (PBMC) proliferation test, and the results were expressed as a stimulation index (SI). We observed an enhanced cellular immune response to gluten (SI > or = 3) in seven of 29 patients with newly diagnosed IDDM (24.1%), in six of 39 patients with a longer duration of IDDM (15.4%), and in two of 37 non-diabetic controls (5.4%). Reactivity of T cells to gluten was associated with IDDM at diagnosis (P = 0.03), whereas patients with longer duration of IDDM did not differ from controls (P = 0.16). Responses of T cells to gluten were low in general: the median SI (range) was 2.0 (1-8.6) in patients with newly diagnosed IDDM and 1.5 (1-5.8) in control subjects (P = 0.03). Cellular responsiveness to gluten was not associated with HLA-DQB1 risk alleles for IDDM in patients. Although T cell responses to gluten were slightly increased in newly diagnosed patients the responsiveness was rare, and thus our results do not support a major role of gluten in the pathogenesis of human IDDM.

Adolescent↗
PubMed1998

TAP2 alleles in inflammatory arthritis.

Sixty patients with reactive arthritis (ReA) and 40 with rheumatoid arthritis (RA), were typed for H LA-B27 and class II antigens DR and DQ, and studied for TAP2 gene polymorphism in comparison with 60 healthy controls. TAP2 polymorphisms at positions 379, 565, 665, and 687 were analyzed using amplification refractory system-based PCR and polymorphisms at positions 386 and 651 using oligonucleotide hybridization. The frequency of the TAP2A/A genotype was 30%(12/40) in RA, in contrast to 13% (8/60) in the controls. This genotype was further associated with DRB1*04 positive RA (10/24, 42%, P=0.01), as well as the TAP2A allele (31/48, 65%, P =0.012). Thr/Thr dimorphism at TAP2 position 665 (24/40, 60%, P=0.024) and Stop/Stop dimorphism at TAP2 position 687 (24/40, 60%, P=0.024) were found to be increased in RA patients as compared to controls. When TAP2I/J polymorphism was studied, TAP2J positivity was found associated with the HLA-B27DR4-DQB1*0301-haplotype in ReA patients. 9/12 of these were positive as compared to 20/60 in random controls (P=0.010). Polymorphisms of the TAP2 gene were found to be associated with subgroups of RA and ReA patients with disease associated markers (e.g. TAP2A in DRB1*04 positive RA, or TAP2J in HLA-B27-DRB1*04-DQB1*0301 positive ReA). These may thus serve as additional markers of specific haplotypes associated with susceptibility to inflammatory arthritis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Tumour necrosis factor microsatellites in reactive arthritis.

The purpose was to study tumour necrosis factor (TNF)-a, -b and -c microsatellites as potential new susceptibility markers for reactive arthritis (ReA). Fifty-nine patients typed for HLA-B27 were studied for frequencies of TNF microsatellite alleles and compared with allele frequencies determined from 285 random haplotypes and 46 healthy HLA-B27-positive controls. TNFa, -b and -c microsatellite sequences were amplified by the polymerase chain reaction, and the size of the product was defined by an automated sequencer. The frequencies of TNFa6 and -c1 alleles were found to be increased in patients with ReA, whereas TNFa11 and -c2 frequencies were decreased as compared to control haplotypes. The increase in the c1 allele in patients with ReA independently from HLA-B27 suggests that it might be a new susceptibility marker for the disease. The association of ReA with other alleles was due to a linkage disequilibrium with HLA-B27.

Alleles↗