Alpha amylase is a major allergenic component in occupational asthma patients caused by porcine pancreatic extract.

Abstract

Porcine pancreatic extracts (PPE) are composed of alpha-amylase and lipase, which are common components of digestive enzymes. They have been known to cause occupational asthma in exposed workers in pharmaceutical and baking industries, as well as in a laboratory technician, but there has been no report of PPE-induced occupational asthma in medical personnel and their IgE binding components to each component. Four asthmatic subjects showing positive results on PPE-bronchoprovocation testing were enrolled. All of them were nurses working in a university hospital. Their job included grinding and mixing PPE powder for admitted patients. Serum-specific IgE antibodies to PPE, alpha-amylase, and lipase were measured by enzyme linked immunosorbent assay (ELISA). To confirm specificity of IgE binding and cross-allergenicity among the three extracts, ELISA inhibition tests were performed. In order to characterize allergenic components within these three extracts, SDS-PAGE and IgE immunoblot analysis were done. Specific IgE antibodies to PPE, alpha-amylase, and lipase were detectable by ELISA in all study subjects. An alpha-amylase ELISA inhibition test showed significant inhibitions by amylase and PPE, and minimal inhibition by lipase. However, a lipase ELISA inhibition test showed significant inhibitions by alpha-amylase and PPE with a lesser degree of inhibition by lipase. Furthermore, IgE immunoblot analysis showed one IgE binding component (55 kDa) within PPE, six components (55 kDa, 43 kDa, 41 kDa, 32 kDa, 31 kDa, 29 kDa) within alpha-amylase and two components (31 kDa, 29 kDa) within lipase extracts. Thesefindings suggest that inhalation of PPE powder can induce IgE-mediated bronchoconstriction in exposed nurses. Alpha-amylase is a major allergenic component within PPE.