ISLET CELL ANTIBODIES IN NORMAL FRENCH SCHOOLCHILDREN

Islet-cell antibodies have been reported to be of predictive value for the future development of Type t (insulin-dependent) diabetes in first degree relatives of diabetic patients with the risk increasing in these subjects with the islet-cell antibodies titre. However, very little is known about islet-cell antibodies in background populations. Sera (n = 8363) from schoolchildren (6-17 years) in the French background population were screened for the presence of islet-cell antibodies by the indirect immunofluorescence technique. Islet-cell antibodies greater than 4.5 Juvenile Diabetes Foundation units were found in 150 sera (prevalence rate 1.8%; 95% confidence interval 1.5-2.1%). Only 17 sera demonstrated islet-cell antibody titre greater-than-or-equal-to 24 JDF units. No particular feature was found to be significantly different between islet-cell antibody-positive and islet-cell antibody-negative children (age, family history of diabetes, fasting plasma glucose, insulin autoantibodies). A second blood sample was obtained from 80 of 150 islet-cell antibody positive children after a mean interval of 8 months. Only 11 sera became < 4.5 JDF units with islet-cell antibody titres being stable in the remaining sera, including the high-titre positive sera (greater-than-or-equal-to 24 JDF units). HLA-DQB typing was performed by restriction mapping techniques in 80 islet-cell antibody-positive, in 93 islet-cell antibody-negative and in 213 Type 1 diabetic children. The distribution of the susceptibility alleles (DQB1-Asp57-negative) was not significantly different between islet-cell antibody-positive and islet-cell antibody-negative children. This survey has identified a low islet-cell antibody prevalence rate in French schoolchildren, among whom the incidence rate of Type 1 diabetes is one of the lowest in Europe. The genetic study indicates that part of this group of children are not prone to developing the disease. The predictive value of islet-cell antibodies in normal children will be estimated during the long-term follow-up of this population.