SKIN-PRICK TESTS FOR HYPERSENSITIVITY TO ALPHA-AMYLASE PREPARATIONS

Twenty-five asthmatic subjects with suspected alpha-amylase hypersensi tivity were studied by skin-prick tests, a capture ELISA, immunoblotti ng and bronchial provocation tests. At the same time, different amylas es were analysed by SDS-PAGE and immunoblotting using a polyclonal rab bit antiserum. Eight patients showed a positive bronchial response to amylase. Seven of them had positive skin-prick tests, with this method being the most sensitive approach for diagnosis. However, in four cas es, skin tests were also positive although the patients had a negative provocation test, thus demonstrating that skin tests are not specific . ELISA and blotting showed similar results in terms of sensitivity an d specificity. The enzymes used by the workers included several antige ns besides alpha-amylase. The rabbit antiserum to alpha-amylase detect ed a protein in a wheat flour extract. In one case, the IgE antibodies were specific only for a contaminant of lower molecular weight than a mylase. These facts suggest that proteins from the culture medium coul d be responsible for some cases of amylase hypersensitivity, making th e diagnosis difficult. The presence of amylase in another enzymatic ex tract, a protease produced by Aspergillus oryzae, was proved by means of skin tests and immunoblotting, thus demonstrating the allergenic pr operties of this enzymatic preparation.