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.