ISLET-CELL SURFACE ANTIBODIES ARE MORE COMMON IN PATIENTS AND RELATIVES IN AREAS AND DURING SEASONS WITH HIGH-INCIDENCE OF INSULIN-DEPENDENT DIABETES-MELLITUS

Although existence of islet cell antibodies (ICA) is regarded as secon dary to beta cell death, islet cell surface antibodies (ICSA) might pl ay a role in the disease process. We have collected information from n ine European clinics to determine whether ICSA are more common in diab etic children or their relatives in geographical areas or time periods of high incidence of insulin-dependent diabetes mellitus (IDDM). In F inland and Sweden (''North group'') with a high incidence of IDDM duri ng childhood, 36% of the patients were positive or weakly positive for ICSA at diagnosis compared with 24% in France (p = 0.1), 11% in Berli n-Vienna (p < 0.01), and 14% in Italy (p < 0.01). This difference was seen in all age groups but was most pronounced in the youngest (0-4 y) . This geographical difference was also seen among family members of w hom 46% were positive or weakly positive in the North group, 25% in Fr ance (p < 0.001), 21% in Berlin-Vienna (p < 0.001), and 16% in Italy ( p < 0.001). Of several analyzed antibodies (ICA, gastric parietal cell , thyroglobulin, and thyroid microsomal), only ICSA showed simultaneou s positivity in all family members (r = 0.32, p < 0.01). ICSA were mos t common in family members of patients with short (<8 d) duration of s ymptoms (p < 0.05) and showed a similar seasonality, both in patients and relatives, as the incidence of IDDM. We conclude that the geograph ical difference in incidence of childhood IDDM in Europe may be associ ated to similar geographical differences in occurrence of ICSA both in newly diagnosed diabetic children and in their relatives. Simultaneou s existence of ICSA in both patients and family members and a similar seasonality for ICSA and incidence of IDDM suggest that ICSA may refle ct an ongoing disease process.