Proteins: chymopapain and insulin.

We studied clinical and immunologic aspects of the reactions to two newly introduced drugs, chymopapain and human recombinant deoxyribonucleic acid insulin (HI), in patients demonstrating allergies to one of these two drugs. We then used this information to improve our ability to diagnose and prevent chymopapain allergy and to further our understanding of systemic insulin allergy and its management. Of the patients who were sensitive to chymopapain, one had severe anaphylaxis to intradisc injection while the other had rhinitis, asthma, and urticaria with occupational exposure. The latter demonstrated cutaneous reactivity to papain; the former refused skin testing. Both demonstrated immunoglobulin (Ig) E and IgG to chymopapain as measured by enzyme-linked immunosorbent assay. We have prospectively skin tested 61 patients with chymopapain. Sixty-one patients have had negative skin tests and have tolerated the intradisc injection of chymopapain without incident. We are continuing our prospective skin test study in order to identify a population at risk for allergy to chymopapain. Two patients with systemic allergic reactions to animal insulin have at least as much cutaneous reactivity and IgE and IgG antibodies to HI as to porcine insulin. A large local reaction occurred during an attempt to desensitize one of them to HI; the patient was subsequently desensitized without difficulty to porcine insulin, to which she was less skin reactive. We conclude that HI will not eliminate insulin allergy in patients with systemic allergy to animal insulin and that such patients will continue to require the usual therapeutic measures for insulin allergy.