11 DOES THE HIGH PREVAIENCE OF CYIOPLASMIC ISLET CELL ANTIBODIES IN A GENERAL FINNISH CHILD POPULATION REFLECT AN INCREASED PREDISPOSTTION FOR INSULIN-DEPENDENT DIABETES (IDOM)?

Abstract

Islet cell antibodies(ICA)have been detected previously in 0.0-0.8% of normal populations. The highest incidence of IDDM reported is in Finland. To find out, whether this is reflected in the prevalence of ICA in the general Finnish population, we studied 1206 normal 3-18 year-old children (558 boys, 46.3%)for conventional(IF-ICA) and complement-fixing(CF-ICA)ICA. The samples for ICA determination were obtained from a study on atherosclerosis precursors started in 1980. Subjects, who turned out to be ICA positive in 1980, were restudied 1983. A cohort of 300 subjects originally negative for ICA in 1980 was restudied in the year 1983 in order to evaluate the annual incidence of ICA.In 1980 tie mean age of subjects was 11.1±5.1 years. Fifty subjects (4.1%) had IF-ICA find 12 of those CF-ICA in their sera(24.0%). 4.5% of boys and 3.9% of girls had IF-ICA while 1.3% of boys and 0.8% of girls were positive for CF-ICA. Tne age distribution was similar in tlie ICA positive and negative groups. At the beginning there wis no significant differaice in the mean IRI levels between IF-ICA positive and negative subjects[9.8 (6.0)mU/l vs.10.1 (5.9)mU/l] or those with or without CF-ICA [7.7 (4.7)mu/l vs.10.1 (6.0)nU/l]. Four (12.9%) of the 31 initially IF-ICA positive children so far re-evaluated had turned negative in 1983, whereas 3 (25.0%) of 12 subjects originally positive for both ICA were CF-ICA negative and 1 (8.3%) had turned negative for both ICA. Among those 300 children negative in 1980 six (2.0%) had turned positive for IF-ICA and 3 (1.0%) for CF-ICA 1983.The high prevalence of ICA in normal Finnish children indicates an increased exposure to B-cell damage predisposing to IDIM. This may contribute to high incidence of IDDM in Finland. However, the conversion from negative to positive observed over a period of 3 years and follow-up results in tlie positive children give support to the suggestion that ICA, in seme cases, may be transient in nature and possibly reflect minor beta cell damage nor necessarily progressing in clinical diabetes.