Immunological complications of insulin therapy have been evident since animal insulin became available for the treatment of diabetes mellitus in 1922 (1). In insulin-allergic patients treated with conventional insulin preparations, the insulin-specific IgE values are often 10- to 20-fold higher than in patients without allergy (2). It has been shown that human insulin is less immunogenic than animal insulin. Porcine insulin is most similar to human insulin.
Review
Insulin is a small protein hormone produced by the beta cells in the Islets of Langerhans. Immunological complications of insulin therapy have been evident since animal insulin became available for the treatment of diabetes mellitus in 1922 (1).
In insulin-allergic patients treated with conventional insulin preparations, the insulin-specific IgE values are often 10- to 20-fold higher than in patients without allergy (2). It has been shown that human insulin is less immunogenic than animal insulin. Porcine insulin is most similar to human insulin. The primary amino acid sequences of bovine and porcine insulin differ from that of human insulin by three and one amino acid, respectively. This greater dissimilarity between human and bovine insulin has been postulated to be the explanation for the greater antigenicity of bovine insulin as compared with porcine insulin (3).
In view of the wide spectrum of immune-mediated complications of insulin therapy, much attention has been directed to the reduced immunogenicity and allergenicity of highly purified porcine insulin and the more recently available recombinant and semi-synthetic human insulin preparations. However, human insulin preparations are not totally non-immunogenic (4-7). Local and acute systemic reactions to exogenous human insulin have occasionally been reported (8,9).
Cross-reactivity between human insulin and insulin of animal origin has been reported (3, 10-15). A major problem is the cross-reactivity that occurs between anti-insulin antibodies and the various animal and human insulin preparations in patients presenting with allergy to animal insulin (3).
