Detection of insulin autoantibodies using an ELISA technique in first-degree relatives of IDDM patients and in autoimmune patients.

We have improved an ELISA technique for the detection of IgG and IgM class IAA demonstrating the sensitivity and the specificity of antigen-antibody reaction. In sera of 135 first degree relatives of IDDM patients and of 128 autoimmune patients "at risk" for IDDM either positive or negative for islet cell antibodies (ICA), the prevalence of IAA IgG/IgM in all groups studied was significantly (p less than 0.001) higher than in controls, but the highest frequency of IAA was observed in the ICA-positive subjects. A similar association was also observed in complement-fixing ICA (CF-ICA) positive subjects. Future prospective studies will be necessary to establish the role of IAA as marker of B-cell damage.