DIAGNOSTIC-TESTS IN ENZYME ALLERGY

Background: Allergies to enzymes occur frequently in enzyme manufactur ing plants. In epidemiologic studies the number of exposed subjects wi th symptoms is considerably higher than the number of sensitizations a s assessed by skin tests or RAST It was the aim of this study to evalu ate the sensitivity and specificity of skin prick tests, enzyme allerg osorbent test, and immunoprint with enzymes by using the results of br onchial provocation tests as the ''gold standard. '' Methods: We perfo rmed 82 bronchial provocation tests with nine different enzymes in 42 chemical plant workers, all of whom had reported work-related symptoms . All tests with the exception of bronchial provocation tests were als o performed in 10 atopic and 10 healthy control subjects. Results: Thi rteen workers showed positive results to bronchial provocation tests ( 50% or greater fall in specific airway conductance) with an enzyme at a maximal concentration of 10 mg/ml Equivocal test results, that is, t ests with a 30% or greater and less than 50% fall in specific airway c onductance were seldom. Skin prick tests with nondialyzed aqueous enzy me extracts at a concentration of 10 mg/ml yielded a sensitivity of 10 0% and a specificity of 93%. Control subjects had no cutaneous reactio ns to enzymes. Discrepancies between skin tests and bronchial provocat ion tests occurred in 5 of 82 tests, all with a positive skin test and a negative bronchial provocation test False-positive skin tests were considered more likely in four subjects and a false-negative bronchial challenge more likely in one case. Enzyme allergosorbent test was 62% sensitive and 96% specific, and atopic control subjects showed positi ve results in two cases. Results of immunoprint with amylase showed on e main band at pH 3.4; this band was also found in exposed subjects wi thout further signs of sensitization, but was not found in control sub jects. All but one person with positive results to bronchial provocati on tests with enzymes showed bronchial hyperresponsiveness. We identif ied 13 subjects with bronchial hyperresponsiveness, but without occupa tional allergy: five of these had sensitizations to nonoccupational al lergens and the remainder showed bronchial hyperresponsiveness without any detectable cause. Conclusions: Occupation-related symptoms were n ot indicative of occupational allergy. Bronchial provocation tests and skin prick tests with nondialyzed aqueous enzyme extracts were approp riate techniques for the diagnosis of enzyme allergy.