ELISA for human IgE antibody to subtilisin A (Alcalase): correlation with RAST and skin test results with occupationally exposed individuals.

An ELISA was developed to detect specific IgE antibody to the Bacillus subtilis-derived proteolytic detergent enzyme, subtilisin A (Alcalase), in sera from exposed detergent workers. Workers in the detergent industry are exposed via inhalation to low levels of the enzyme dust in the presence of detergent dust. Chemically inactivated Alcalase was used as the test antigen. Significant binding of IgE antibody to the immobilized enzyme was detected in the ELISA. The binding of allergic antibody to Alcalase was specifically inhibited in a dose-dependent manner by preincubating sera with 0.1 to 100 micrograms of inactivated Alcalase. Binding of IgE antibody to Alcalase could not be inhibited by two other inactivated bacterial proteases, Savinase and Esperase, derived from different Bacillus species. ELISA and skin test results demonstrated total agreement for 27 of 31 samples (87%), whereas RAST and skin test results demonstrated total agreement for only 24 of 31 samples (77%), indicating that the ELISA was more sensitive than the RAST. We conclude that the ELISA is a sensitive, fast, alternative to the RAST for detection of Alcalase-specific IgE antibody in detergent enzyme-exposed workers.