Insulin-specific IgE in serum of 67 diabetic patients against human insulin (Novo), porcine insulin, and bovine insulin. Four case reports.

We have investigated the binding of insulin-specific IgE (IgE1) to porcine, bovine, and human insulin (Novo), pancreatic polypeptide, and a-component in serum samples from type I diabetic patients treated with insulin preparations of different purity. Patients treated with porcine or mixed-species purified insulin (monocomponent) did not differ significantly from a nondiabetic control group. Hence, in these groups no IgE1 could be detected against any of the components investigated. Serum samples from patients treated with five-times recrystallized insulin preparations and patients with insulin allergy showed a significantly greater binding of IgE1 to the three species of insulin; IgE1 binding was greatest to bovine insulin and least to human insulin. The difference in binding was most significant in the allergic patients (P less than 0.001), probably due to differences in the affinity. It is concluded that conventional (recrystallized) insulin induces more IgE1 than monocomponent insulin. Data are presented on confirmed allergy in four diabetic patients whose allergy disappeared upon transfer to human insulin.