IgE to Poppy Seed and Morphine Are Not Useful Tools to Diagnose Opiate Allergy

Correct diagnosis of genuine IgE-mediated opiate allergy poses a significant challenge, mainly because of uncertainties associated with opiate skin testing and the unavailability of drug-specific IgE (sIgE) assays. Recently, it has been suggested that sIgE to poppy seed extract and morphine would be reliable in the diagnosis of opiate allergy. However, given the high prevalence of sIgE antibodies to these compounds in an allergic population, the predictive value of these tests leaves significant doubts.

This study aims at verifying the predictive value of positive poppy seed and morphine sIgE assays results.

A total of 22 individuals with a positive sIgE to poppy seed or morphine were selected. All had controlled drug challenges with increasing doses of morphine and/or codeine. Of these, 18 patients had an additional basophil activation test (BAT) with morphine and codeine.

None of the 22 patients demonstrated objective or subjective symptoms on provocation with morphine and/or codeine. Regarding BAT with morphine and codeine, expression of CD63 on basophils from 14 opiate tolerant individuals remained comparable to spontaneous expression by resting cells. The remaining 4 patients were classified as nonresponders.

Positive sIgE results to poppy seed and morphine are not per se predictive for genuine opiate allergy and should not be used in isolation to diagnose morphine or codeine allergy. To avoid overdiagnosis, for the time being, we propose to supplement serological diagnosis with an oral provocation test. Whether BAT might help to discriminate between clinical reactivity and sensitization remains to be confirmed in larger collaborative studies.