Allergy from cellulase and xylanase enzymes

A guide to mycetisms: A toxicological and preventive overview

Fungi are often considered a delicacy and are primarily cultivated and harvested, although numerous species are responsible for intoxication due to toxin content. Foodborne diseases are a significant public health concern, causing approximately 420 000 deaths and 600 million morbidities yearly, of which mushroom poisoning is one of the leading causes. Epidemiological data on non-cultivated mushroom poisoning in individual countries are often unrepresentative, as intoxication rarely requires emergency intervention. On the other hand, the lack of specialist knowledge among medical personnel about the toxicological manifestations of mushroom consumption may result in ineffective therapeutic interventions. This work aims to provide an easy-to-consult and wide-ranging tool useful for better understanding the variability of mushroom intoxications, the associated symptoms, and the main treatments for the most severe cases, given the absence of a complete species mapping tool toxic. Moreover, we establish an effective collection network that describes the incidence of mushroom poisonings by reporting the species and associated toxicological manifestations for each case. In conclusion, we highlight the need to establish appropriate primary prevention interventions, such as training the affected population and increasing consultancy relationships between mycological experts and specialised healthcare personnel.

Safety evaluation of the food enzyme endo-1,4-β-xylanase from the genetically modified Bacillus subtilis strain XAN

The food enzyme endo-1,4-β-xylanase (4-β-d-xylan xylanohydrolase, EC 3.2.1.8) is produced with the genetically modified microorganism Bacillus subtilis strain XAN by DSM Food Specialties B.V. The genetic modifications do not give rise to safety concerns. The food enzyme is free from viable cells of the production organism and its DNA. The production strain of the food enzyme contains antimicrobial resistance genes. However, based on the absence of viable cells and DNA from the production organism in the food enzyme, this is not considered to be a risk. The food enzyme is intended to be used in baking processes and cereal-based processes. Dietary exposure to the food enzyme total organic solids (TOS) was estimated to be up to 0.02 mg TOS/kg body weight (bw) per day in European populations. As no other concerns arising from the microbial source and its subsequent genetic modification or from the manufacturing process have been identified, the Panel considered that toxicological tests are not needed for the assessment of this food enzyme. A search for similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic reactions by dietary exposure cannot be excluded, but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Safety evaluation of the food enzyme endo-1,4-β-xylanase from the genetically modified Trichoderma reesei strain NZYM-ER

The food enzyme endo-1,4-β-xylanase (4-β-d-xylan xylanohydrolase; EC 3.2.1.8) is produced with the genetically modified Trichoderma reesei strain NZYM-ER by Novozymes A/S. The genetic modifications do not give rise to safety concerns. The food enzyme is considered free from viable cells of the production organism and its DNA. The food enzyme is intended to be used in brewing processes, distilled alcohol production, grain treatment for the production of starch and gluten fractions and for palm oil production. Since residual amounts of total organic solids (TOS) are removed by distillation, in palm oil production and in grain treatment for the production of starch and gluten fraction, dietary exposure was only calculated for brewing processes. Dietary exposure to the food enzyme TOS was estimated to be up to 0.09 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1,051 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure, results in a margin of exposure of at least 11,400. A search for similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that, under the intended conditions of use (other than distilled alcohol production) the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood for this to occur is considered to be low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Safety evaluation of the food enzyme xylanase from Bacillus pumilus (strain BLXSC)

The food enzyme 1,4-β-d-xylan xylanohydrolase (EC 3.2.1.8) is produced with the non-genetically modified strain Bacillus pumilus (strain BLXSC) by Advanced Enzyme Technologies Ltd. The food enzyme is intended to be used in baking processes, grain treatment for the production of starch and gluten fractions, and distilled alcohol production. Since residual amounts of the food enzyme are removed by distillation and during grain treatment, dietary exposure was only calculated for baking processes. Based on the maximum recommended use levels for baking processes, and individual data from the EFSA Comprehensive European Food Database, dietary exposure to the food enzyme-Total Organic Solids (TOS) was estimated to be up to 0.138 mg TOS/kg body weight (bw) per day. As the production strain of B. pumilus meets the requirements for a Qualified Presumption of Safety (QPS) approach, no toxicological data are required. Similarity of the amino acid sequence to those of known allergens was searched and no match was found. The Panel considered that under the intended conditions of use (other than distilled alcohol production), the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but is considered to be low. Based on the QPS status of the production strain and the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Performance of specific immunoglobulin E tests for diagnosing occupational asthma: a systematic review and meta-analysis

OBJECTIVES

To determine the test performance parameters for the retrievable range of high-molecular-weight (HMW) and low-molecular-weight (LMW) occupational allergens and to evaluate the impact of allergenic components and the implementation of measures for test validation.

METHODS

A protocol with predefined objectives and inclusion criteria was the basis of an electronic literature search of MEDLINE and EMBASE (time period 1967-2016). The specific inhalation challenge and serial peak flow measurements were the reference standards for the specific IgE (sIgE) test parameters. All of the review procedures were reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

RESULTS

Seventy-one studies were selected, and 62 entered meta-analysis. Pooled pairs analysis indicated a sensitivity of 0.74(95% CI 0.66 to 0.80) and specificity of 0.71(95% CI 0.63 to 0.77) for HMW allergens and a sensitivity of 0.28(95% CI 0.18 to 0.40) and specificity of 0.89(95% CI 0.77 to 0.95) for LMW allergens. Component-specific analysis improved the test parameters for some allergens. Test validation was handled heterogeneously among studies.

CONCLUSION

sIgE test performance is rather satisfactory for a wide range of HMW allergens with the potential for component-specific approaches, whereas sensitivity for LMW allergens is considerably lower, indicating methodological complications and/or divergent pathomechanisms. A common standard for test validation is needed.

Sensitization to xylanolytic enzymes: an underestimated health hazard among bakers

BACKGROUND

The most important occupational allergens in baking include flour and enzymes, especially α-amylase. Although xylanolytic enzymes have previously been described as sensitizers, they may be overlooked during assessment of bakery workers with work-related symptoms.

AIMS

To report a case of a baker who suffered from work-related respiratory, ocular and skin symptoms as a consequence of sensitization to xylanolytic enzymes.

METHODS

Physical examination, chest X-ray, routine laboratory tests, skin prick tests (SPTs) with common and occupational allergens (wheat, pearl, rye, corn and oat flours, α-amylase, bakery adjuvants) and spirometric measurements, as well as assessments by a laryngologist, dermatologist and ophthalmologist were performed. Specific IgE (sIgE) to occupational agents were evaluated for flours, α-amylase, xylanase, cellulose and glucoamylase. Specific inhalation challenges (SICs) with flours and bakery adjuvants were carried out.

RESULTS

Hypersensitivity to Aspergillus moulds, flours and α-amylase was confirmed in SPTs; however, SIC with those agents gave a negative result. Further investigation revealed the presence of sIgE to xylanolytic enzymes. During SIC with bakery adjuvants, allergic skin, ocular and respiratory symptoms occurred and were confirmed by objective assessment.

CONCLUSIONS

In the assessment of work-related allergic symptoms in bakers, sensitization to xylanolytic enzymes should be considered. Completion of diagnostic procedures having excluded asthma and rhino-conjunctivitis related to flour hypersensitivity might result in a false-negative assessment.

Industrial fungal enzymes: an occupational allergen perspective

Occupational exposure to high-molecular-weight allergens is a risk factor for the development and pathogenesis of IgE-mediated respiratory disease. In some occupational environments, workers are at an increased risk of exposure to fungal enzymes used in industrial production. Fungal enzymes have been associated with adverse health effects in the work place, in particular in baking occupations. Exposure-response relationships have been demonstrated, and atopic workers directly handling fungal enzymes are at an increased risk for IgE-mediated disease and occupational asthma. The utilization of new and emerging fungal enzymes in industrial production will present new occupational exposures. The production of antibody-based immunoassays is necessary for the assessment of occupational exposure and the development of threshold limit values. Allergen avoidance strategies including personal protective equipment, engineering controls, protein encapsulation, and reduction of airborne enzyme concentrations are required to mitigate occupational exposure to fungal enzymes.

Lung disease in flavoring and food production: learning from butter flavoring

Workers in the food industry are exposed to multiple respiratory hazards that include irritants, allergens, and substances capable of causing destruction and scarring of the lungs. Cases of constrictive bronchiolitis obliterans, a severe potentially disabling lung disease, have been identified in workers exposed to flavorings. Workplace engineering controls, work practices, and respiratory protection can minimize potential exposures. Medical surveillance of workers exposed to known respiratory hazards will help to identify disease early, facilitate the prompt removal of workers from the causative exposure(s), and prevent further worsening and/or permanence of disease. When companies or employees suspect occupational respiratory disease, they can involve public health agencies to investigate any excess risk of lung disease, risk factors among processes and exposures, and effectiveness of interventions, if needed.

Occupational asthma related to mouse allergen exposure and rhinoconjunctivitis due to collagenase inhalation in a laboratory technician

We describe the case of a 27-year-old patient working in a research laboratory, who developed occupational asthma to mouse proteins and presented symptoms of rhinoconjunctivitis caused by manipulation of collagenase. Specific inhalation challenge confirmed the diagnosis of occupational asthma to mouse proteins, whereas specific challenge with collagenase only evoked symptoms of rhinitis and conjunctivitis. SDS-PAGE and Western blot analysis for collagenase showed that the patient's IgE antibodies bound specifically to a protein with a molecular weight of 92 kDa. Hence, this was an unusual case of double sensitization. The sensitization to collagenase presented in this report may represent a new occupational disease in technicians working in medical or research laboratories.

Inhibition of 1,4-beta-D-xylan xylanohydrolase by the specific aspartic protease inhibitor pepstatin: probing the two-step inhibition mechanism

This is the first report that describes the inhibition mechanism of xylanase from Thermomonospora sp. by pepstatin A, a specific inhibitor toward aspartic proteases. The kinetic analysis revealed competitive inhibition of xylanase by pepstatin A with an IC50 value 3.6 +/- 0.5 microm. The progress curves were time-depended, consistent with a two-step slow tight binding inhibition. The inhibition followed a rapid equilibrium step to form a reversible enzyme-inhibitor complex (EI), which isomerizes to the second enzyme-inhibitor complex (EI*), which dissociated at a very slow rate. The rate constants determined for the isomerization of EI to EI* and the dissociation of EI* were 15 +/- 1 x 10(-5) and 3.0 +/- 1 x 10(-8) s(-1), respectively. The Ki value for the formation of EI complex was 1.5 +/- 0.5 microm, whereas the overall inhibition constant Ki* was 28.0 +/- 1 nm. The conformational changes induced in Xyl I by pepstatin A were monitored by fluorescence spectroscopy, and the rate constants derived were in agreement with the kinetic data. Thus, the conformational alterations were correlated to the isomerization of EI to EI*. Pepstatin A binds to the active site of the enzyme and disturbs the native interaction between the histidine and lysine, as demonstrated by the abolished isoindole fluorescence of o-phthalaldehyde-labeled xylanase. Our results revealed that the inactivation of xylanase is due to the interference in the electronic microenvironment and disruption of the hydrogen-bonding network between the essential histidine and other residues involved in catalysis, and a model depicting the probable interaction between pepstatin A with xylanase has been proposed.

Skin as a route of exposure to protein allergens

Protein contact with skin is associated with a number of clinical conditions, including protein contact dermatitis and immunologic contact urticaria. This article reviews the clinical and other selected evidence that proteinaceous materials penetrate skin. It is concluded that whilst penetration of intact proteins through normal skin is extremely low and without consequence, any damage to the skin barrier may allow penetration. As a result, risk assessment for contact of protein with skin must take into account potential barrier impairment and thus the possibility of both the induction and the elicitation of allergic skin reactions.

Slow-tight binding inhibition of xylanase by an aspartic protease inhibitor: kinetic parameters and conformational changes that determine the affinity and selectivity of the bifunctional nature of the inhibitor

The first report of slow-tight inhibition of xylanase by a bifunctional inhibitor alkalo-thermophilic Bacillus inhibitor (ATBI), from an extremophilic Bacillus sp. is described. ATBI inhibits aspartic protease (Dash, C., and Rao, M. (2001) J. Biol. Chem., 276, 2487-2493) and xylanase (Xyl I) from a Thermomonospora sp. The steady-state kinetics revealed time-dependent competitive inhibition of Xyl I by ATBI, consistent with two-step inhibition mechanism. The inhibition followed a rapid equilibrium step to form a reversible enzyme-inhibitor complex (EI), which isomerizes to the second enzyme-inhibitor complex (EI*), which dissociated at a very slow rate. The rate constants determined for the isomerization of EI to EI*, and the dissociation of EI* were 13 +/- 1 x 10(-6) s(-1) and 5 +/- 0.5 x 10(-8) s(-1), respectively. The K(i) value for the formation of EI complex was 2.5 +/- 0.5 microm, whereas the overall inhibition constant K(i)* was 7 +/- 1 nm. The conformational changes induced in Xyl I by ATBI were monitored by fluorescence spectroscopy and the rate constants derived were in agreement with the kinetic data. Thus, the conformational alterations were correlated to the isomerization of EI to EI*. ATBI binds to the active site of the enzyme and disturbs the native interaction between the histidine and lysine, as demonstrated by the abolished isoindole fluorescence of o-phthalaldehyde (OPTA)-labeled Xyl I. Our results revealed that the inactivation of Xyl I is due to the disruption of the hydrogen-bonding network between the essential histidine and other residues involved in catalysis and a model depicting the probable interaction between ATBI or OPTA with Xyl I has been proposed.

Occupational airway sensitizers: an overview on the respective literature

BACKGROUND

Worldwide, there is rigorous scientific activity concerning the further development of work safety regulations involving airway-sensitizing substances. Technical directives on hazardous substances are enforced in several countries and are being continuously updated. The European Union has established a code for several occupational substances, now labeled R 42 ("may cause sensitization by inhalation").

METHODS

We present an overview of the literature dealing with allergic occupational asthma. The literature was selected according to criteria of study design and diagnostic test methods. Approximately 300 publications were reviewed including both epidemiological studies and individual case reports.

RESULTS

Airway sensitizers are systematically arranged and separately listed according to chemicals and their origin from animals, plants, and microorganisms. The clinical data as well as threshold limit values (TLV) and R 42 labeling of 250 airway-sensitizing substances are presented.

CONCLUSIONS

The most common sensitizing substances causing occupational asthma were dust of cereal flours, enzymes, natural rubber latex, laboratory animals as well as low molecular substances such as isocyanates and acid anhydrides.

The tertiary structure at 1.59 A resolution and the proposed amino acid sequence of a family-11 xylanase from the thermophilic fungus Paecilomyces varioti bainier

We report the crystal structure at 1.59 A and the proposed amino acid sequence of an endo-1,4-beta-xylanase (PVX) from the thermophilic fungus Paecilomyces varioti Bainier (PvB), stable up to 75 degrees C. This fungus is attracting clinical attention as a pathogen causing post-surgical infections. Its xylanase, known as a skin-contact allergen, is the first protein from this fungus whose three-dimensional structure has been elucidated. The crystals of PVX conform to the space group P2(1)2(1)2(1 )with a=38.76 A, b=54.06 A and c=90.06 A. The structure was solved by molecular replacement techniques using polyalanine coordinates of the Thermomyces lanuginosus xylanase (PDB code 1YNA) and a careful model building based on the amino acid sequence known for two trypsin-digested peptide fragments (17 residues), the sequence and structural alignment of family-11 xylanases and electron density maps. The final refined model has 194 amino acid residues and 128 water molecules, with a crystallographic R-factor of 19.07 % and a free R-factor of 21.94 %. The structure belongs to an all-beta fold, with two curved beta-sheets, forming the cylindrical active-site cleft, and a lone alpha-helix, as present in other family-11 xylanases. We have carried out a quantitative comparison of the structure and sequence of the present thermophilic xylanase (PVX) with other available native structures of mesophiles and thermophiles, the first such detailed analysis to be carried out on family-11 xylanases. The analysis provides a basis for the rationalisation of the idea that the "hinge" region is made more compact in thermophiles by the addition of a disulphide bridge between Cys110 and Cys154 and a N-H.O hydrogen bond between Trp159 near the extremity of the lone alpha-helix and Trp138 on beta-strand B8. This work brings out explicitly the presence of the C-H.O and the C-H.pi type interactions in these enzymes. A complete description of structural stability of these enzymes needs to take account of these weaker interactions.

Occupational asthma and IgE sensitization to cellulase in a textile industry worker

BACKGROUND

Although there have been a few reports of occupational asthma due to cellulase in several occupational settings, this is the first case of cellulase-induced occupational asthma in an employee working in the textile industry. Its pathogenetic mechanism remains to be further clarified.

OBJECTIVE

It is important to alert physicians to the possibility of occupational asthma caused by cellulase in workers of the textile industry.

METHODS AND RESULTS

The patient had atopy and strong positive responses to cellulase extract on skin prick tests. Bronchoprovocation test showed an early asthmatic response to cellulase extract. Serum specific IgE and specific IgG4 antibodies to cellulase were detected by enzyme-linked immunosorbent assay (ELISA). In order to further characterize the allergenic component of the extract, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and electroblotting studies were performed. Eight IgE binding components ranging from 6 to 97.5 kD were detected within the cellulase extract.

CONCLUSION

These findings suggest that inhalation of cellulase can induce IgE-mediated bronchoconstrictions in employees working in the textile industry.

Baker's asthma due to the enzyme xylanase -- a new occupational allergen

The asthmatic baker showed IgE-mediated sensitization to xylanase of Aspergillus niger used as a baking additive. Inhalative challenge with approximately 0.5 microg of the enzyme resulted in an immediate-type asthmatic reaction. This case, as well as a preliminary screening of symptomatic bakers, shows that xylanase is a further relevant type I-sensitizer in the baking industry.

Allergy to Aspergillus-derived enzymes in the baking industry: identification of beta-xylosidase from Aspergillus niger as a new allergen (Asp n 14)

BACKGROUND

Aspergillus-derived enzymes are used in dough improvers in bakeries. Some of these enzymes are identified as causing IgE-mediated sensitization in up to 25% of bakers with workplace-related symptoms.

OBJECTIVE

The aim of this study was to compare the frequency of sensitization to Aspergillus xylanase, cellulase, and glucoamylase with the sensitization to alpha-amylase (Asp o 2) and to identify IgE-reactive proteins in enzyme preparations.

METHODS

Sensitization to Aspergillus-derived enzymes and cross-reactivity were retrospectively studied by enzyme allergosorbent test (EAST) and EAST-inhibition experiments. IgE-reactive proteins were detected by electrophoretic separation and immunoblotting. Liquid chromatography with electrospray ionization mass spectrometry and Edman degradation of tryptic protein fragments were used for the biochemical identification of an unknown IgE-binding protein.

RESULTS

Twenty-three percent of 171 tested bakers had specific IgE to alpha-amylase, 8% reacted to glucoamylase, 13% reacted to cellulase, and 11% reacted to xylanase. Xylanase and cellulase preparations, each containing at least 6 different proteins, showed cross-reactivity in the range of 80%. The main IgE-binding protein in the xylanase preparation recognized in 7 of 8 xylanase-positive subjects was a protein of about 105 kd. This protein was identified as beta-xylosidase by peptide mass spectrometric fingerprinting. The identification was confirmed by matching 12 peptide sequences obtained by N-terminal and mass spectrometric sequencing to this protein.

CONCLUSIONS

Beta-Xylosidase from Aspergillus niger is an occupational allergen present in currently used baking additives, which causes sensitization in at least 4% of symptomatic bakers. According to the International Union of Immunological Societies nomenclature, we suggest the term Asp n 14 for this allergen.

Enzymatic activity of soluble phospholipase A2 does not affect the specific IgE, IgG4 and cytokine responses in bee sting allergy

BACKGROUND

The soluble bee venom phospholipase A2 (PLA) represents the major allergen/antigen for allergic and hyperimmune individuals following bee sting. A number of studies implicate enzymes, and PLA in particular, as potent allergens. We have studied specific activation of T cells by enzymatically active and inactive mutants of PLA, and secretion of cytokines regulating IgE and IgG4 antibody formation.

METHODS

Recombinant (r) wild type PLA (rPLA-WT) and an enzymatically inactive rPLA (rPLA-H34Q) were produced in Escherichia coli. Eleven bee venom allergic patients and three hyperimmune, healthy individuals were included in the study. After specific stimulation of PBMC with the rPLA variants, proliferative response, IFNgamma, IL-2, IL-4, IL-5, and IL-13 production, as well as total and PLA-specific IgE and IgG4 production, were analysed.

RESULTS

Similar levels of specific B cell recognition, proliferative and cytokine responses were observed after stimulation with either enzymatically active or inactive rPLA. In addition, equal amounts of antigen-specific and total IgE and IgG4 antibodies were produced by stimulation with both forms of rPLA.

CONCLUSIONS

The enzymatic activity of PLA does not influence the specific activation and cytokine production by T cells from bee venom-sensitized or hyperimmune individuals, or the IgE/IgG4 antibodies synthesis by B cells in vitro.

Statistical data on occupational contact urticaria

Data on occupational contact urticaria (protein contact dermatitis included) in Finland during 1990-1994 were analyzed. Altogether 815 cases were reported to the Finnish Register of Occupational Diseases during this period, compared with 1944 cases of occupational allergic contact dermatitis. Accordingly, the total number of occupational allergic contact dermatoses was 2759, 29.5% being contact urticaria and 70.5% being allergic contact dermatitis. Occupational contact urticaria was much more common in women (70%) than in men (30%). The 6 most common causes of contact urticaria were (1) cow dander (362 cases = 44.4%), (2) natural rubber latex (193 cases = 23.7%), (3) flour, grains and feed (92 cases = 11.3%), (4) handling of foodstuffs (25 cases = 3.1%), (5) industrial enzymes (14 cases = 1.7%) and (6) decorative plants (13 cases = 1.6%). The occupations with the highest numbers of occupational contact urticaria were farmers (341 cases), domestic animal attendants (61), bakers (53), nurses (42), chefs (40) and dental assistants (28). The ranking list of the most common occupations with occupational contact urticaria per 100,000 employed workers was as follows: (1) bakers (140.5 cases per 100,000 employed persons), (2) preparers of processed food, (3) dental assistants, (4) veterinary surgeons, (5) domestic animal attendants, (6) farmers and silviculturalists, (7) chefs, cooks and cold buffet managers, (8) dairy workers, (9) horticultural supervisors, (10) laboratory technicians and radiographers, (11) physicians, (12) butchers and sausage makers, (13) laboratory assistants, (14) dentists and (15) nurses (21.2 cases per 100,000 employed person). Low-molecular-weight chemicals caused very few cases of occupational contact urticaria, the most common being 2-ethylhexyl acrylate (5 cases). To summarize, occupational contact urticaria forms a large group of occupational contact dermatoses, and dermatologists need to be able to diagnose IgE-mediated immediate skin allergic diseases.

Enzyme exposure and enzyme sensitisation in the baking industry

OBJECTIVES

To assess the exposure to enzymes and prevalence of enzyme sensitisation in the baking industry.

METHODS

A cross sectional study was conducted in four bakeries, one flour mill, and one crispbread factory. Sensitisation to enzymes, flours, and storage mites was examined by skin prick and radioallergosorbent (RAST) tests. 365 workers were tested. The workers were interviewed for work related respiratory and skin symptoms. Total dust concentrations were measured by a gravimetric method, and the concentration of alpha-amylase in air was measured by a catalytic method. An immunochemical method was used for measuring cellulase and xylanase in air.

RESULTS

Total measured dust concentrations were from 0.1 to 18 mg/m3, with highest values in dough making areas of bakeries. The alpha-amylase concentrations generally followed the total dust concentrations and reached the highest values < 6.6 micrograms/m3 in the same areas. Cellulase and xylanase varied with concentrations < 180 ng/m3 and < 40 ng/m3, respectively, in the flour mill and the crispbread factory. No cellulase, but concentrations of 1-200 ng/m3 xylanase, were found in the bakeries, probably indicating the natural xylanase activity of wheat. 12 workers (8%) in the bakeries, three (5%) in the flour mill, and four (3%) in the crispbread factory were skin prick positive to enzymes. The corresponding percentages of positive reactions to flours were 12%, 5%, and 8%.

CONCLUSIONS

The study confirmed that industrial enzymes in baking used as additives in a powdered form pose a risk of sensitisation. The no effect air concentrations for industrial enzymes are not known. Based on present knowledge, however, lowering exposures and eliminating short and high peaks by technical measures would lower the risk of sensitisation. This would be most effectively accomplished by shifting to non-dusty products.

A major house dust mite allergen disrupts the immunoglobulin E network by selectively cleaving CD23: innate protection by antiproteases

Asthma is a chronic life-threatening disease of worldwide importance. Although allergic asthma and related atopic conditions correlate strongly with immune sensitization to house dust mites, it is unclear why antigens from mites provoke such powerful allergic immune responses. We have characterized the protease activity of Der p I, the group I protease allergen of the house dust mite Dermatophagoides pteronyssinus, and here report that it cleaves the low-affinity immunoglobulin (Ig) E Fc receptor (CD23) from the surface of human B lymphocytes. Der p I selectively cleaves CD23 and has no effect on the expression of any other B cell surface molecules tested. We speculate that this loss of cell surface CD23 from IgE-secreting B cells may promote and enhance IgE immune responses by ablating an important feedback inhibitory mechanism that normally limits IgE synthesis. Furthermore, since soluble CD23 is reported to promote IgE production, fragments of CD23 released by Der p I may directly enhance the synthesis of IgE. alpha 1-Antiprotease, a pulmonary antiprotease, is also shown to inhibit the cleavage of CD23 by Der p I. This may be significant in the etiopathogenesis of asthma, because other indoor pollutants associated with asthma are known to potently inhibit this antiprotease. These data suggest that the proteolytic activity of Der p I, the group I allergen of the house dust mite D. pteronyssinus, is mechanistically linked to the potent allergenicity of house dust mites. Furthermore, inhibition of Der p I by alpha 1-antiprotease suggests a mechanism by which confounding factors, such as tobacco smoke, may act as a risk factor for allergic asthma.

Pharyngeal edema caused by occupational exposure to cellulase enzyme

Enzymes can cause allergic asthma and rhinitis. Although patients sometimes complain of symptoms in their throat, we have not been able to find any published report of pharyngeal edema caused by exposure to enzymes. We present the case of a maintenance foreman who worked in a factory producing enzymes, and who had pharyngeal edema, asthma, and rhinitis at work. Prick tests for cellulase enzyme and cellulase RAST were positive. The causal association between his pharyngeal symptoms and cellulase was demonstrated with inhalation provocation tests in an exposure chamber.

[Occupational asthma caused by organic substances]

Occupational asthma (OA) to organic substances is frequently related to IgE-dependent hypersensitivity. New etiological agents are latex and vegetal gums, in health care personnel as in carpet-making manufactures. Bakers are exposed to numerous allergens: wheat and cereal flours, sesame and other seed proteins, alpha-amylase and other enzymes. Alpha-amylase extracted from Aspergillus orizae is a potent allergen. Plant derived materials have been identified as allergens in the floral industry (Ficus, Ginseng, Gypsophila, etc). The accurate diagnosis relies upon a thorough history, completed by measurements of peak expiratory flows during the work. Sensitization can be confirmed by prick tests and immuno assays for IgE antibodies. Bronchial provocation tests documenting OA are advisable. The early detection of OA might be evaluated by skin tests to occupational allergens repeated yearly. The prevention of OA relies on air sampling technologies controlling the allergenic density of the atmosphere and removing asthmatics from exposed areas. There are no scientific grounds for discarding atopics from occupations at risk for OA.

Occupational allergic rhinitis in Finland

Between 1980 and 1987 a total of 166 patients were diagnosed as having occupational (mostly allergic) rhinitis at the Institute of Occupational Health. This is about 20% of all the diagnosed cases in Finland. The most common causes were: flour (50 cases), wood dust (30 cases), animal epithelia (19 cases), and natural fibers, mainly cotton (19 cases). Between 1981 and 1987 the number of cases of occupational rhinitis in all of Finland more than doubled (from 61 to 128 cases per year), and in 1991 a total of 319 cases were detected. This was mainly due to the increase in rhinitis caused by animal epithelium and flour dust, which were then the most common causes of occupational rhinitis in Finland. This increase, in turn, was based on changes in the Finnish legislation, which in 1982 was extended to cover farmers. Other causes of the increase were probably the increased awareness of the public and health personnel, but a true increase in occupational rhinitis cannot be excluded.

Respiratory allergy to Aspergillus-derived enzymes in bakers' asthma

Baking and food industry workers are exposed to several powdered Aspergillus-derived enzymes with carbohydrate-cleaving activity that are commonly used to enhance baked products. We describe a retrospective study of sensitization to fungal alpha-amylase and cellulase on bakers. Five bakers in whom respiratory allergy symptoms developed when they were exposed to bread "improvers" that contained fungal alpha-amylase and cellulase were investigated by in vivo and in vitro tests. Type I hypersensitivity to these enzymes was demonstrated in the five patients by means of skin testing, histamine release test, positive reverse enzyme-immunoassay for specific IgE antibodies, and bronchial provocation test response to alpha-amylase or cellulase or both. Isolated immediate and dual responses to the bronchial challenge tests with these enzymes were observed. Immunoblot analysis with use of a pooled serum identified IgE-binding components in both enzymes. In the reverse-enzyme immunoassay-inhibition assays cross-reactivity between alpha-amylase and cellulase was not found, but some degree of cross-reactivity between alpha-amylase and A. oryzae, and between cellulase and A. niger was demonstrated. Four of the patients were also sensitized to cereal flour. Aspergillus-derived enzymes used as flour additives can elicit IgE-mediated respiratory allergy, and this fact has to be considered in the diagnosis and clinical management of bakers' asthma.