A highly sensitive enzyme immunoassay of anti‐insulin antibodies in human serum

Abstract

AbstractA highly sensitive enzyme immunoassay of anti‐insulin antibodies in human serum is described. Serum samples were subjected to successive processes of the incubation with insulin, the dextran‐charcoal treatment to remove free insulin, the precipitation of insulin anti‐insulin antibodies by polyethylene glycol, the acid treatment of the precipitates to inactivate anti‐insulin antibodies, and the measurement of insulin by sandwich enzyme immunoassay technique. By this enzyme immunoassay, anti‐insulin antibodies were demonstrated in most of serum samples from patients who had been treated with insulin for 0.6–24 months. The detection limit of anti‐insulin IgG in human serum was 1,000 to 3,000‐fold less than that obtained by the previously reported enzyme immunoassay, in which an insulin‐coated polystyrene ball was incubated with diluted serum and subsequently with (antihuman IgG γ‐chain) Fab'‐horseradish peroxidase conjugate. The present enzyme immunoassay may be useful for the measurement of antibodies for not only insulin but also other antigens that are not precipitated by polyethylene glycol.