IgE and IgG antibody against human (recombinant DNA) insulin in patients with systemic insulin allergy

We demonstrated IgE and IgG antibodies to human (rDNA) insulin as well as to bovine and porcine insulin in the serum of two patients with systemic insulin allergy by an enzyme-linked immunosorbent assay. We also demonstrated IgE and total antibody binding to bovine insulin with the use of radioimmunoassays. Both patients had cutaneous reactivity to all three insulins. When the serum of one patient was preincubated with human, porcine, or bovine insulin, there was inhibition of binding of the patient's IgE and IgG antibodies to human insulin. The other patient had very low levels of IgE antibodies to insulin and thus only IgG inhibition was possible. Preincubation with human insulin inhibited binding of each patient's antibodies to bovine or porcine insulin. We conclude that, for these two patients, human insulin has all the antigenic determinants that bovine and porcine insulin have. Therefore, human insulin for these two patients will not eliminate insulin allergy in all patients with systemic allergy to animal insulin, because there are patients whose antibodies recognize determinants common to commercial human, bovine, and porcine insulin.