Glucanase, β-

Sensitisation data (human)

Administrative data

Endpoint:

sensitisation data (humans)

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Report of occupational asthma due to phytase and ß-glucanase

Author:

T M O’Connor, J F Bourke, M Jones, N Brennan

Year:

2001

Bibliographic source:

Occup Environ Med 2001;58:417–419

Materials and methods

Type of sensitisation studied:

respiratory

Study type:

case report

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Inhalation challenge tests were performed with the enzymes phytase, ß-glucanase, and amylase. Skin prick tests were performed with the enzymes. Specific IgE to phytase and ß-glucanase were measured with a radioallergosorbent test.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Glucanase, β-

EC Number:

232-979-7

EC Name:

Glucanase, β-

Cas Number:

9074-98-0

Molecular formula:

not available (see remarks)

IUPAC Name:

endo-1,4-ß-glucanase IUBMB EC 3.2.1.4

Constituent 2

Reference substance name:

Amylase, α-

EC Number:

232-565-6

EC Name:

Amylase, α-

Cas Number:

9000-90-2

IUPAC Name:

I ,4-a-D-glucan glucanohydrolase

Constituent 3

Reference substance name:

Phytase

Cas Number:

9001-89-2

IUPAC Name:

Phytase

Method

Type of population:

occupational

Ethical approval:

not applicable

Subjects:

A 43 year old company director of an animal feed manufacturing plant.
None of 22 other workers in the factory had asthma or had developed respiratory symptoms at work. His company had begun to manufacture animal feeds containing the enzyme phytase 1 year previously. The main other components of these feeds were various vitamins, trace elements, and the enzymes amylase and ß-glucanase. ß-Glucanase had been introduced to the factory 9 years previously.

Clinical history:

An 8 week history of wheezing and coughing that began on arrival at work and abated while away from the factory. Asthma had been diagnosed 7 years previously by his general practitioner, and had been well controlled on inhaled steroid and ß-agonist therapy. There was no history of allergic rhinitis or contact dermatitis. He was a non-smoker. There was a strong family history of asthma (mother, brother, and son were affected). He had been employed in his current occupation for 14 years.

Controls:

No

Route of administration:

other: inhalation and dermal

Details on study design:

Physical examination indicated expiratory wheeze. A chest radiograph was normal and serum IgE was 48 KU/l (normal <100 KU/l). Histamine challenge tests were performed. Inhalation challenge tests were performed with the enzymes phytase, ß-glucanase, and amylase at weekly intervals, the patient having avoided the workplace for 10 days before testing. The patient was asymptomatic at the beginning of each challenge, and minor variations found in baseline spirometry values were thought to reflect the natural variability in these values found in patients with asthma. Pure enzymes were obtained in powder form from their manufacturers, and the patient was exposed by pouring the powder from cup to cup near his face for 3 minutes. Pulmonary function was performed with the Jaeger Masterlab spirometer. The same technician performed all the tests. The tests were performed with the subject sitting in a chair breathing through a mouthpiece with a nose clip. The best results of three flow volume manoeuvres were used. Spirometry values were obtained immediately before and 15 minutes after exposure. Pulmonary function was performed in accordance with the guidelines recommended by the American Thoracic Society.
Skin prick tests were performed with positive and negative controls and with the enzymes diluted to a concentration of 1 mg/mL and 5 mg/mL. Reactions were measured at 15 minutes. Reaction of 5 mm or more, and 3 mm more than the negative control were considered positive. Specific IgE to phytase and ß-glucanase were measured with radioallergosorbent test. Briefly, 3 mg of allergen was coupled to 300 mg cyanogen activated paper discs according to the method of Ceska et al. For the assay, serum (50 μL) was added to a disc. After incubation at room temperature for 16 hours, the disc was washed and added to 50 μL I-antihuman IgE. After 16 hours at room temperature, the disc was washed and counted in a γ scintillation counter. The amount of antigen specific IgE was expressed as the percentage of the added counts per minute (cpm) that remained bound to the disc (percentage binding). Two per cent binding is chosen conventionally as a positive cut off; 1%–2% is considered to be borderline. Unexposed populations do not exceed the 1% RAST binding level. Cord blood was used as a negative control.

Results and discussion

Results of examinations:

Histamine challenge testing showed bronchial hyperresponsiveness (provocative concentration causing a 20% fall in forced expired volume in 1 second (PC20) was 1 mg/mL). Skin tests showed a positive reaction to ß-glucanase (5 mm) at a concentration of 1 mg/mL and positive reactions to ß-glucanase (7 mm) and phytase (5 mm) at a concentration of 5 mg/mL. There were no significant reactions to amylase. Similarly specific IgE was present against both phytase and ß-glucanase, with 2.5% and 9.3% binding respectively. Cord blood was negative in both RAST assays.
Baseline spirometry values were normal. On exposure to the enzymes phytase and ß-glucanase, the patient developed symptoms of cough, wheeze, and rhinorrhoea. Spirometry values after exposure showed significant reductions in forced vital capacity and forced expired volume in 1 second (see ‘Any other information on results incl. tables’). No significant differences were noted after exposure to amylase.

Any other information on results incl. tables

Spirometric values (L) before and after exposure to enzymes 

Enzyme	Spirometry	Baseline	After challenge	% Change
Amylase	FVC	4.50 (93)	4.53 (93)	0
	FEV1	3.17 (80)	3.08 (78)	-3
ß-Glucanase	FVC	4.70 (97)	3.85 (79)	-18
	FEV1	3.41 (86)	2.53 (64)	-26
Phytase	FVC	4.54 (94)	4.02 (83)	-11
	FEV1	3.92 (99)	2.82 (71)	-28

Predicted FVC 4.85L, predicted FEV1 3.96L, percentage of predicted values in parentheses.