Background: In vitro tests for detecting drug-specific IgE would be useful in identifying patients at risk for immediate hypersensitivity reactions to therapeutic doses of a drug.
Objective: We attempted to verify that IgE-mediated reactions to erythromycin occur and to identify IgE antibodies specific for erythromycin in serum from a patient who had urticaria immediately after administration of the drug.
Methods: Skin prick testing was performed on the patient and five control subjects. Serum from the patient, pooled sera from nonatopic subjects allergic to common aeroallergens, and cord blood controls were analyzed for erythromycin-specific IgE by radioimmunoassay. Sepharose (Pharmacia, Uppsala, Sweden) was used as solid phase covalently linked to erythromycin.
Results: We were able to detect erythromycin-specific IgE antibodies in serum from the patient who had an allergic reaction to this antibiotic, but specific IgE could not be detected in control sera.
Conclusion: Immunologic IgE-mediated reactions to erythromycin do occur, and in vitro diagnosis of such reactions can be made by using Sepharose as a solid phase covalently linked to this drug.