Does The Presence Of Autoantibodies To Endogenous Insulin Affect The Immunological Response To Exogenous Insulin Treatment?
Insulin autoantibodies (IAA) are frequently found in newly diagnosed untreated insulin-dependent diabetics. In this study, it was evaluated whether the presence of insulin autoantibodies produced prior to insulin treatment affected the insulin antibody response over the first year of treatment with insulin. Patients with IAA were compared against those without IAA. One hundred and five previously untreated type 1 diabetics were randomly assigned to treatment with either pure porcine or mixed bovine/porcine insulin. Twenty-one in each group had detectable IAA at diagnosis. Percent binding rose in all patients after commencing insulin therapy and was significantly greater in those with IAA irrespective of the type of insulin administered. The elevated binding in the IAA positive patients at all time points was equivalent to the binding that could be attributed to the insulin autoantibodies. These data suggest that the greater insulin antibody found in the IAA positive patients during insulin therapy is due to the summation of binding due to insulin autoantibodies and binding due to insulin antibodies formed in response to the exogenous insulin. Physiologically, the insulin antibody response in the IAA positive versus negative patients is probably equivalent suggesting that different clones of lymphocytes produced the IAA versus the insulin antibodies that developed in response to insulin treatment.