Abstract

OBJECTIVES Occupational asthma is the principal cause of respiratory disease in the workplace. The enzymes phytase and β-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 man was suspected.

METHODS Inhalation challenge tests were performed with the enzymes phytase, β-glucanase, and amylase. Skin prick tests were performed with the enzymes diluted to a concentration of 1 mg/ml and 5 mg/ml. Specific IgE to phytase and β-glucanase were measured with a radioallergosorbent test.

RESULTS Baseline spirometry values were normal. A histamine challenge test showed bronchial hyperreactivity. Exposure to phytase and β-glucanase led to significant reductions in forced vital capacity and forced expired volume in 1 second. No significant differences were noted after exposure to amylase. Skin tests showed a positive reaction to β-glucanase (5 mm) at a concentration of 1 mg/ml and positive reactions to β-glucanase (7 mm) and phytase (5 mm) at a concentration of 5 mg/ml. Similarly specific IgE was present against both phytase and β-glucanase, at 2.5% and 9.3% binding respectively (2% binding is considered positive).

CONCLUSIONS This is the first description of occupational asthma due to the enzymes phytase and β-glucanase. Their addition to the ever increasing list of substances associated with occupational asthma will have notable implications for those exposed to these enzymes.