Usefulness of patch tests for diagnosing selective allergy to captopril

Captopril, enalapril, and lisinopril are angiotensin-converting enzyme (ACE) inhibitors widely prescribed for hypertension and heart failure. Cutaneous side effects of captopril include angio-edema, anaphylactoid reactions, maculopapular eruptions, pitiryasis rosea-like rash, toxic erythema, and exfoliative dermatitis. Some of the immunological captopril-induced cutaneous adverse reactions have been diagnosed in recent years by patch tests. A case of a cutaneous immune adverse reaction to captopril with tolerance to enalapril and lisinopril demonstrated both by patch tests and double-blind challenge tests is reported for the first time. A 71-year-old nonatopic woman suffered a generalized pruriginous maculopapular rash. Two months earlier, she had started oral treatment with captopril 50 mg t.i.d and glibenclamide 5 mg daily. After the rash appeared, she stopped both drugs and the reaction cleared. A skin biopsy from one of the lesions showed perivascular lymphocytic infiltrate of the upper dermis. Skin prick tests with captopril and glibenclamide and patch tests with enalapril, lisinopril, and glibenclamide at 1% and 10% pet., and with mercaptobenzothiazole (a sulfhydryl group-containing chemical at 1% pet were negative. Only patch tests with captopril at 1% and 10% concentrations were positive at 48 h. Oral double-blind challenge tests with glibenclamide, enalapril, lisinopril, and placebo showed good tolerance. The patient was advised to avoid only captopril. Because captopril is the only ACE inhibitor containing a sulfhydryl group and has occasionally been implicated in complex immunological diseases, this chemical group has been considered the culprit of allergic reactions to captopril. The lack of cross-reactivity between captopril, enalapril, and benazepril has been demonstrated in a few patients by patch tests. In our patient, patch tests identified captopril as the drug responsible for a probably immune adverse reaction not due to the sulfhydryl group. Patch tests are useful and safe in the diagnostic work-up of allergic drug reactions and in studies of cross-sensitivity among ACE inhibitors.

Platanus acerifolia pollinosis and food allergy

BACKGROUND

In Mediterranean areas, oral allergy syndrome (OAS) occurs independently of an associated birch pollinosis; moreover, on occasions it presents with no other associated pollinosis. The aim of this study was to assess the possible association of OAS with Platanus acerifolia pollinosis.

METHODS

We evaluated consecutive patients seen for pollinosis in an allergy department. Seven hundred and twenty patients were selected on the basis of seasonal or perennial rhinitis, or asthma, or both. Respiratory and food allergies were studied in all patients. Clinical history was recorded and examinations and skin prick tests were performed with a battery of available common inhalant allergens and plant-derived food allergens. Specific IgE levels to P. acerifolia pollen extract and food allergens tested were measured. Molecular masses of the IgE-binding proteins and cross-reactivity among the P. acerifolia pollen and different food extracts were also determined.

RESULTS

Of the 720 patients evaluated, 61 (8.48%) were sensitized to P. acerifolia pollen. Food allergy was observed in 32 (52.45%) of the 61 patients sensitized to P. acerifolia pollen. Food allergens most frequently implicated were hazelnuts, peach, apple, peanuts, maize, chickpea and lettuce. Enzyme allergosorbent (EAST)-inhibition showed high inhibition values when P. acerifolia pollen extract was used as free phase. On the contrary low inhibition was observed when plant-derived food allergens were used as free phase and P. acerifolia pollen extract as solid phase.

CONCLUSIONS

Cross-reactivity was observed among P. acerifolia pollen and plant-derived foods. OAS in these patients may have been caused by primary respiratory sensitization.