k206 Savinase

Exposure

Unexpected exposure

See under Geographical distribution and Environment.

Description

Savinase is an enzyme produced by Bacillus amyloliquefaciens.

Occupational

An occupational allergen, which may frequently induce hayfever, asthma and conjunctivitis in sensitised individuals.

Allergens

No allergenic epitopes from this substance have yet been characterised.

Antigenic and allergenic characteristics of the enzymes Alcalase and Savinase and their potential cross-reactivity were evaluated using crossed immunoelectrophoresis and crossed radioimmuno-electrophoresis. Alcalase exhibited 2 distinct antigens, 1 electropositive and 1 electronegative. Savinase exhibited 1 electropositive and 2 electronegative antigens. The antigens of the 2 enzymes were clearly different from each other, the 3 Savinase antigens exhibiting greater electrophoretic mobility than the 2 Alcalase antigens. In crossed radioimmunoelectrophoresis studies, only the electropositive antigen of Alcalase, its retrograde complex, and the electropositive antigen of Savinase bound IgE from the sera of individuals who were skin test-positive to one or both enzymes (4).

Potential Cross Reactivity

In a group of detergent enzyme workers with known exposure to Alcalase/Maxatase, sensitisation to Savinase, to which there was no previous occupational exposure, was demonstrated by skin-specific IgE. The researchers attributed this to either cross-reactivity between these enzymes or to foreign enzyme contaminants contained in the Savinase antigen (5).

No evidence of cross-reactivity was observed between Alcalase and Savinase in heterologous and tandem crossed immunoelectrophoresis studies and heterologous microimmunodiffusion reactions (4).

Clinical Experience

IgE-mediated reactions

Since the 1960s an increasing number of occupational allergies against natural and modified recombinant enzymes has been reported. Subtilisins have been shown to cause allergic reactions, in particular airway sensitisation. Symptoms, results of skin prick tests, detection of specific IgE antibodies, and results of specific bronchoprovocation tests have confirmed an immunologic mechanism for these high-molecular-weight antigens (6-15). Those affected are mainly workers in the detergent industry rather than consumers (16-20).

Occupational allergy to enzyme detergents has almost disappeared due to the use of preventive measures, both individually and in industries. Nonetheless, incomplete application of preventive measures within a factory may result in new instances of sensitisation and allergic disease (14).

A close relationship has been described between bronchial hyperresponsiveness and the provocation dose of an enzyme. Researchers have reported that bronchopulmonary testing with enzyme solutions is highly sensitive and specific in confirming the diagnosis of occupational asthma due to these proteolytic enzymes (15). Specific IgE tests have also been reported to be very useful in the diagnosis of sensitisation to these enzymes (16).

Not all the enzymes are equipotent in inducing allergic sensitisation. In guinea pig models, Termamyl was about 10-fold more potent than Alcalase/Maxatase, and the protease subtilisin B was shown to be less potent than these. Savinase was shown to be equivalent in potency to Alcalase/Maxatase. Prospective evaluation of skin-specific IgE tests of factory workers showed that sensitisations to Termamyl and Savinase were similar to sensitisations to Alcalase. The sensitisations to subtilisin B were weaker than those to Alcalase (21).

Sixty-five workers in a detergent industry were divided into 4 groups according to their prick test results, as follows: those positive for at least 1 enzyme (Lipolase, Savinase) (group I, n = 15); enzyme-negative cases (group II, n = 50); and from among these, enzyme-positive non-smoking cases (group Ia, n = 11); and enzyme-negative non-smoking cases (group IIa, n = 32). The observation that the FVC and FEV(1) of the workers were much lower than expected, especially among those sensitive to the enzymes, independently of occupational asthma and cigarette smoking, led to the conclusion that the cause might be sensitivity to the enzymes (20).

Eight new cases of asthma in a detergent factory led to a prospective clinical and aetiological enquiry. Sensitisation to the enzymes used (Savinase, Maxatase and Biozym P 300 S) was shown by skin tests (8 positive to all the enzymes), by the level of specific IgE to Rast (8 times greater than class 3 for Savinase and Maxitase), and by HBDT for Maxatase and Biozym P 300 S (greater than 50% in 8 patients). The incomplete application of preventive measures within the factory did not seem to completely explain the origin of this sensitisation. The study of the morphology of the enzyme grains that had been introduced into the factory helped to explain the mechanism. The capsules of the grain were fissured, allowing allergen contact. The replacement of these grains with others whose envelope was intact led to the disappearance of the symptoms and confirmed the hypothesis (14).

Other reactions

A 53-year-old woman developed respiratory symptoms while working with a cleaner containing subtilisins. Her symptoms intensified in the work environment and improved away from work. Computed tomography demonstrated alveolar and interstitial infiltrates with subsequent scarring. Pulmonary function showed a restrictive pattern with diminished diffusion capacity. Bronchoalveolar lavage showed lymphocytosis, and all cultures were negative. Precipitating antibodies to the enzyme were found in the patient's serum. These findings supported a diagnosis of extrinsic allergic alveolitis from the enzyme contained in the cleaner (22).