IA-2 antibody isotypes and epitope specificity during the prediabetic process in children with HLA-conferred susceptibility to type I diabetes.

The natural history of preclinical diabetes is partly characterized, but there is still limited information on the dynamics of the immune response to beta-cell autoantigens during the course of preclinical disease. The aim of this work was to assess the maturation of the humoral immune response to the protein tyrosine phosphatase(PTP)-related proteins (IA-2 and IA-2beta) in preclinical type I diabetes (TID). Forty-five children participating in the Finnish Type I Diabetes Prediction and Prevention (DIPP) Study who had seroconverted to IA-2 antibody positivity were analysed. Specific radiobinding assays were used to determine IA-2/IA-2beta epitope-specific antibodies (the juxtamembrane (JM) region of IA-2, PTP-like domain and betaPTP-like domain) and isotype-specific IA-2 antibodies. Individual areas under the curve (AUC) over the observation period were calculated for total IA-2 antibodies, each isotype and specific epitope responses. The children who progressed to TID tended to have an initial IA-2 JM epitope response more frequently (P = 0.06), and this response was more often dominant during the observation period (P < 0.05). The children who did not progress to TID had IgE-IA-2 more frequently (70%; versus progressors 27%; P < 0.05), and had higher integrated titres of IgE-IA-2 antibodies (P < 0.05). The occurrence of IgE-IA-2 antibodies was protective even when combined with positivity for IA-2 JM antibodies (P = 0.002). IgE-IA-2 antibody reactivity may be a marker of a regulatory immune response providing protection against or delaying progression to TID among IA-2 antibody-positive young children with HLA-conferred disease susceptibility.

Infant feeding patterns in the Finnish type I diabetes prediction and prevention nutrition study cohort.

OBJECTIVE: To investigate infant feeding patterns during the first 2 y and their relation to sociodemographic factors. DESIGN: A population-based cohort study. SETTING: Oulu and Tampere University Hospital district areas 1996-1999, Finland. SUBJECTS AND METHODS: All newborn infants (n=675) with increased genetic risk for type I diabetes were invited to the study in 1996-1997. Of these, 429 (64%) completed the dietary follow-up form by the time they reached 2 y of age. RESULTS: The median duration of exclusive breastfeeding (BF) was 1.8 months (range 0-6 months) and that of total BF 7.0 months (0.3-25 months). Among the infants 20% were exclusively breastfed at least 4 months (recommendation 4-6 months). Infants were introduced to infant formula at the median age of 1.8 months (range 0-25 months) and other supplementary foods at the median age of 3.5 months (1-6 months). Infant's ponderal index at birth was inversely associated with the duration of total BF. The age of introduction of supplementary foods correlated positively with the duration of total BF. Longer parental education and increased maternal age were associated with a longer duration of BF and older age at introduction of supplementary foods. Infant formula and other supplementary foods were added earlier to the diet of the boys than that of the girls. CONCLUSION: Duration of breastfeeding in Finland is shorter than recommended. Compliance with the current recommendations on the timing of introduction of first supplementary food and dairy products is relatively poor. The diet during infancy seems to be conspicuously influenced by the duration of parental education, maternal age and the sex of the infant.