Report of occupational asthma due to phytase and beta-glucanase

Objectives-Occupational asthma is the principal cause of respiratory diseas e in the workplace. The enzymes phytase and beta -glucanase are used in the agricultural industry to optimise the nutritional value of animal feeds. A relation between these enzymes and occupational asthma in a 43 year old ma n was suspected. Methods-Inhalation challenge tests were performed with the enzymes phytase, beta -glucanase, and amylase. Skin prick tests were performed with the enz ymes diluted to a concentration of 1 mg/ml and 5 mg/ml. Specific IgE to phy tase and beta -glucanase were measured with a radio-allergosorbent test. Results-Baseline spirometry values were normal. A histamine challenge test showed bronchial hyperreactivity. Exposure to phytase and beta -glucanase l ed to significant reductions in forced vital capacity and forced expired vo lume in 1 second. No significant differences were noted after exposure to a mylase. Skin tests showed a positive reaction to beta -glucanase (5 mm) at a concentration of 1 mg/ml and positive reactions to beta -glucanase (7 mm) and phytase (5 mm) at a concentration of 5 mg/ml. Similarly specific IgE w as present against both phytase and beta -glucanase, at 2.5% and 9.3% bindi ng respectively (2% binding is considered positive). Conclusions-This is the first description of occupational asthma due to the enzymes phytase and beta -glucanase. Their addition to the ever increasing list of substances associated with occupational asthma will have notable i mplications for those exposed to these enzymes.