Insulin autoantibodies and immune response to human insulin therapy in 24 type 1 (insulin-dependent) diabetic children: superiority of radio binding assay over solid phase assay

To evaluate the immunization pattern against human insulin, 24 newly diagnosed diabetic children (12 females, 12 males; mean age: 7 ± 4 years) were treated from diagnosis onwards with semisynthetic human insulin (NOVO). Informed consent was obtained from all parents. Blood samples were taken before, 1, 2, 3, 4, 6 and 8 weeks after the start of therapy and, thereafter, at monthly intervals for 2 years. Insulin (auto) antibodies (I(A)A) were measured by radio binding assay (RBA) and by enzyme-linked immunosorbent assay (ELISA). IAA, determined by RBA, were detected in eight children. Using ELISA, IgM IA were not detected after onset of therapy. By contrast, IgG IA were found in 8 children after 2 weeks of treatment and in 12 after 1 month. Using RBA, all children had IA after 2 months of therapy, whereas with ELISA, IA remained undetectable during the study period in 8 out of 24 patients. These results confirm previous observations suggesting that the 2 methods are not interchangeable and yield different estimations of the insulin immune reaction, not only before but also after the start of insulin therapy. In addition, the detection of IA by RBA in all treated patients unambiguously demonstrates that human insulin is immunogenic in man. © 1993.