Occupational asthma and rhinoconjunctivitis from inhalation of dried cow's milk caused by sensitization to alpha-lactalbumin

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Sensitization to cow's milk protein in a dairy worker

Background

Repeated skin exposure and inhalation of milk proteins may lead to IgE-mediated sensitization, normally manifested at the site of contact. Although this is a phenomenon predominantly found in children, it has also been observed in adults.

Aims

To describe a case of a worker who, after being exposed to milk proteins for many years, eventually experienced episodes of anaphylaxis.

Case report

A 62-year-old worker experienced severe episodes of anaphylaxis following the intake of dairy products. He had worked in the dairy industry for 17 years, where he was exposed to dried milk every day.

Conclusions

This case report illustrates how continued exposure to milk proteins, either by skin contact or inhalation, may lead to sensitization which could result in severe manifestations of anaphylaxis.

Allergen component analysis as a tool in the diagnosis and management of occupational allergy

We are now in the epoch of "molecular allergology" and numerous clinically relevant allergenic molecules are available improving the performance of in vitro allergen tests and allergen detection methods. This review is focusing on characterized occupational allergens and their implementation into the in vitro diagnosis for occupational allergy and in allergen detection methods. More than 400 occupational agents are identified and documented as being 'respiratory sensitizers', but currently only a limited number of them are characterized on the molecular level and available for routine diagnosis as native or recombinant allergens. One exception, however, is natural rubber latex (NRL) from Hevea brasiliensis still remaining an important occupational allergen source. Characterization of 15 NRL allergens led to the development of assays for the determination of allergen content of NRL materials and the implementation of component-resolved diagnosis (CRD) for specific IgE antibody measurement. Microarray or singleplex using recombinant or native allergens are reliable tools for NRL allergy diagnosis. In addition, NRL allergy is an excellent model for improving extract-based specific IgE measurement by amplification of NRL extract preparation with stable recombinant major allergen rHev b 5. Despite the many efforts to characterize the occupationally relevant wheat allergens for baker's asthma, the most frequently occurring forms of occupational asthma, the results are highly diverse. Wheat sensitization profiles of bakers showed great interindividual variability and no wheat allergen could be classified as the major allergen. For diagnosis of baker's asthma, a whole wheat extract is still the best option for specific IgE determination. But single wheat allergens might help to discriminate between wheat-induced food allergy, grass pollen allergy and baker's asthma. For workplace-related allergens like coffee, wood, soybean, seafood and moulds allergens are characterized and few of them are available, but their relevance for occupational sensitization routes should be verified in the further studies.

Addressing Molecular Diagnosis of Occupational Allergies

PURPOSE OF REVIEW

Numerous clinically relevant allergenic molecules enhance the performance of specific (s) IgE tests and improve the specificity of allergy diagnosis. This review aimed to summarize our current knowledge of the high-molecular-weight allergens involved in the development of occupational asthma and rhinitis and to critically analyze the contribution of component-resolved diagnosis in the management of these conditions.

RECENT FINDINGS

There is a lack of standardization and validation for most available extracts of occupational agents, and assessment of sIgE reactivity to occupational allergen components has been poorly investigated, with the notable exception of natural rubber latex (NRL) and wheat flour. In the case of NRL, the application of recombinant single allergens and amplification of natural extracts with stable recombinant allergens improved the test sensitivity. IgE-sensitization profile in patients with baker's asthma showed great interindividual variation, and extract-based diagnostic is still recommended. For other occupational allergens, it remains necessary to evaluate the relevance of single allergen molecules for the sensitization induced by occupational exposure. Progress has been made to characterize occupational allergens especially NRL and wheat, although there is still an unmet need to increase the knowledge of occupational allergens, to include standardized tools into routine diagnostic, and to evaluate their usefulness in clinical practice.

Allergenicity of casein containing chalk in milk allergic schoolchildren

BACKGROUND

Nondietary exposure to milk proteins may be a risk for children who do not outgrow milk allergy by school age.

OBJECTIVE

To study the allergenicity of casein containing chalk.

METHODS

A 6-year-old, milk allergic child developed asthma and rhinoconjunctivitis while in school. The suspected cause was dust-free chalk containing casein. To study the relationship of dust-free chalk containing casein with asthma and rhinoconjunctivitis, 13 additional milk allergic patients were studied: 3 school-aged children, 8 preschool-aged infants, and 2 children with outgrown milk allergy. Skin tests and/or specific IgE with chalk and casein were performed. A chalk use test was performed in older children. Milk allergens contained in chalk were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot, and IgE inhibition experiments.

RESULTS

All school-aged, milk allergic children were exposed to chalk and reported symptoms attributed to chalk exposure. The skin test result to chalk was positive in 5 of 12 cases, and the specific IgE test result was positive in all 12 study participants in which it was performed. Casein strongly inhibited the binding of IgE to chalk. Chalk sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed proteins with molecular weight similar to caseins. Immunoblot demonstrated strong binding of IgE to chalk in a blurred pattern and a band at 30 kDa, inhibited by casein. The chalk challenge test result was positive in 2 school-age children who had a positive skin test result to chalk. Their symptoms improved after avoidance of chalk in the school. In 2 other cases in which the challenge test result was negative, chalk was reintroduced without problems.

CONCLUSION

Inhalation of chalk dust containing casein can induce asthma symptoms in milk allergic patients. Hidden and nondietary sources of exposure should always be considered in food allergic patients.

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.

Allergic reactions to foods by inhalation

Although allergic reactions to foods occur most commonly after ingestion, inhalation of foods can also be an underlying cause of these reactions. For example, published reports have highlighted the inhalation of allergens from fish, shellfish, seeds, soybeans, cereal grains, hen's egg, cow's milk, and many other foods in allergic reactions. Symptoms have typically included respiratory manifestations such as rhinoconjunctivitis, coughing, wheezing, dyspnea, and asthma. In some cases, anaphylaxis has been observed. In addition, there have been many investigations of occupational asthma following the inhalation of relevant food allergens. This report reviews the current literature focusing on allergic reactions to foods by inhalation.

Milk consumption does not lead to mucus production or occurrence of asthma

There is a belief among some members of the public that the consumption of milk and dairy products increases the production of mucus in the respiratory system. Therefore, some who believe in this effect renounce drinking milk. According to Australian studies, subjects perceived some parameters of mucus production to change after consumption of milk and soy-based beverages, but these effects were not specific to cows' milk because the soy-based milk drink with similar sensory characteristics produced the same changes. In individuals inoculated with the common cold virus, milk intake was not associated with increased nasal secretions, symptoms of cough, nose symptoms or congestion. Nevertheless, individuals who believe in the mucus and milk theory report more respiratory symptoms after drinking milk. In some types of alternative medicine, people with bronchial asthma, a chronic inflammatory disease of the lower respiratory tract, are advised not to eat so-called mucus-forming foods, especially all kinds of dairy products. According to different investigations the consumption of milk does not seem to exacerbate the symptoms of asthma and a relationship between milk consumption and the occurrence of asthma cannot be established. However, there are a few cases documented in which people with a cow's milk allergy presented with asthma-like symptoms.

Relevance of inhalational exposure to food allergens

PURPOSE OF REVIEW

This review discusses the inhalational route as a clinically important route of exposure to food allergens.

RECENT FINDINGS

In childhood, we have recently demonstrated that food allergens can induce both early and late phase bronchial reactions within blinded, placebo-controlled challenges. Additionally, clinically important levels of food allergens have been measured in environmental air samples.

SUMMARY

It is well known that the ingestion of food allergens frequently causes respiratory symptoms and that the mechanism of death in fatal anaphylaxis is usually profound bronchospasm. The mechanism by which ingested food allergens induce bronchial reactions is unclear. There are many case reports of bronchial reactions to aerosolized food allergens. Within the food industry the problems have been examined more systematically. From such work it is possible to gain an impression of the potential prevalence of the problem. With 10% of adult asthma being occupational and 10% of occupational asthma being induced by aerosolized food, inhalational exposure to food allergens plays a major role in at least 1% of adult asthma. For a patient with co-existent food allergy and asthma it is important that both dietary and environmental avoidance be practised. The similar pathophysiology of allergic and occupational asthma and the ability of inhaled food allergens to cause the latter raises the question as to whether aerosolized food could play a role in the pathogenesis of childhood asthma.

Stability of bovine allergens during food processing

OBJECTIVE

The primary objective of this review was to summarize reported findings about the influence of various food manufacturing processes on the potential alteration of bovine allergens in cow's milk, beef, and related food products.

DATA SOURCES

This review was based on literature research in two German databases.

STUDY SELECTION

The expert opinion of the authors was used to select the relevant data for the review.

RESULTS

Changes in allergenic activity during food processing are attributable to inactivation or destruction of epitope structures, formation of new epitopes, or improved access of previously hidden epitopes. The allergenic potency of food could be altered by several food manufacturing procedures--such as mechanical, purification, thermal, biochemical, and chemical processes. The main processing steps studied by investigators were heating (dry heating, boiling, or cooking) and enzymatic digestion. A review of the available literature on the alteration of bovine allergens in cow's milk, meat, and related food products revealed reduction (but not elimination) of allergenicity by heating of cow's milk for 10 minutes. Although homogenization did not change the allergenic potency of cow's milk, it decreased the allergenicity of beef, as did freeze-drying. Digestion studies showed varied results.

CONCLUSIONS

The allergenicity of some food products decreased during certain processing steps, but the results of other investigations differed. Therefore, more systematic research on the influence of food processing on allergenicity should be undertaken.

Stability of food allergens and allergenicity of processed foods

The allergenicity of food could be altered by several processing procedures. For various foods of animal and plant origin the available literature on this alteration is described. Investigations on hidden allergens in food products are also dealt with.

Recurrent milk aspiration produces changes in airway mechanics, lung eosinophilia, and goblet cell hyperplasia in a murine model

Recurrent aspiration of milk into the respiratory tract has been implicated in the pathogenesis of a variety of inflammatory lung disorders including asthma. However, the lack of animal models of aspiration-induced lung injury has limited our knowledge of the pathophysiological characteristics of this disorder. This study was designed to evaluate the effects of recurrent milk aspiration on airway mechanics and lung cells in a murine model. Under light anesthesia, BALB/c mice received daily intranasal instillations of whole cow's milk (n = 7) or sterile physiologic saline (n = 9) for 10 d. Respiratory system resistance (Rrs) and dynamic elastance (Edyn,rs) were measured in anesthetized, tracheotomized, paralyzed and mechanically ventilated mice 24 h after the last aspiration of milk. Rrs and Edyn,rs were derived from transrespiratory and plethysmographic pressure signals. In addition, airway responses to increasing concentrations of i.v. methacholine (Mch) were determined. Airway responses were measured in terms of PD(100) (dose of Mch causing 100% increase from baseline Rrs) and Rrs,max (% increase from baseline at the maximal plateau response) and expressed as % control (mean +/- SE). We found recurrent milk aspiration did not affect Edyn and baseline Rrs values. However, airway responses to Mch were increased after milk aspiration when compared with control mice. These changes in airway mechanics were associated with an increased percentage of lymphocytes and eosinophils in the bronchoalveolar lavage, mucus production, and lung inflammation. Our findings suggest that recurrent milk aspiration leads to alterations in airway function, lung eosinophilia, and goblet cell hyperplasia in a murine model.

Caffeine for asthma

BACKGROUND

Caffeine has a variety of pharmacological effects. It is chemically related to the drug theophylline which is used to treat asthma. Accordingly, interest has been expressed in its potential role as an asthma treatment. A number of studies have explored the effects of caffeine in asthma, this is the first review to systematically examine and summarise the evidence.

OBJECTIVES

Caffeine is a weak bronchodilator and it also reduces respiratory muscle fatigue. It has been suggested that caffeine may reduce asthma symptoms. The objective of this review was to assess the effects of caffeine on lung function and identify whether there is a need to control for caffeine consumption prior to lung function testing.

SEARCH STRATEGY

We searched the Cochrane Airways Group trials register and the reference lists of articles. We also contacted study authors.

SELECTION CRITERIA

Randomised trials of oral caffeine compared to placebo in adults with asthma.

DATA COLLECTION AND ANALYSIS

Trial quality assessment and data extraction were done independently by two reviewers.

MAIN RESULTS

Six trials involving a total of 55 people were included. The studies were all of cross-over design and of high quality. In comparison with placebo, caffeine appears to improve lung function for up to two hours after consumption. Forced expiratory volume in one minute showed a small improvement up to two hours after caffeine use (standardised mean difference -0.73, 95% confidence interval -1.20 to -0.25). Mid-expiratory flow rates also showed a small improvement with caffeine and this was sustained up to four hours.

REVIEWER'S CONCLUSIONS

Caffeine appears to improve airways function modestly in people with asthma for up to four hours. People may need to avoid caffeine for at least four hours prior to lung function testing.

[Asthma caused by food allergy]

Food allergy (FA) induced asthma is less common than FA induced atopic dermatitis, or angioedema. The incidence reaches 8.5%. Occupational asthma due to the inhalation of various food proteins is increasingly described. Egg proteins could be peculiarly at risk. In the childhood, all the kinds of foods can be incriminated. In adults, FA are predominantly due to vegetal allergens, included in the following botanical families: rosaceae, umbelliferae, and exotic fruits. Bronchi are sensitized either by inhalation of food allergens or by inhalation of cross-reactive pneumoallergens, such as pollens, feathers, latex. The fact that FA might create a bronchial hyperreactivity is controversial. Bronchial challenges induce late-phase reactions and document the acquisition of an inflammatory state. The quantity of allergens gaining access to bronchi plays a major part in the triggering of asthma. It can be modulated by variations of intestinal permeability which are related to viral infections, aspirin, alcohol, etc. The chemical characteristics of proteins, such as hydrophobicity might interfere with the passage through the gut mucosa. The diagnosis is based upon skin tests and the detection of specific IgE, identifying the state of hypersensitivity. Provocation tests are mandatory to establish FA. The pharmacological approach of the treatment is less important than the eviction insofar as the specific immunotherapy is not yet currently performed.

Immune reactivity of cow-asthmatic dairy farmers to the major allergen of cow (BDA20) and to other cow-derived proteins. The use of purified BDA20 increases the performance of diagnostic tests in respiratory cow allergy

BACKGROUND

Cow dust is one of the most important inducers of occupational allergic diseases in Finland. For example, in 1991 it accounted for almost 40% of the new occupational asthma cases.

OBJECTIVE

This study compares the performance of the purified major cow allergen (BDA20) and crude bovine epithelial extract (BEA) in diagnostic tests and examines the role of milk allergy-associated bovine proteins (bovine serum albumin, alpha-lactalbumin, beta-lactoglobulin, casein) in respiratory cow allergy.

METHODS

The humoral responses of cow-asthmatic and healthy farmers to the various components of BEA were analysed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The levels of specific IgE and IgG antibodies were quantificated with enzyme-linked immunosorbent assays (ELISAs). The cellular responses were analysed with antigen-specific lymphocyte proliferation tests.

RESULTS

The specific anti-BDA20 IgE measurement was found to be best in distinguishing between the asthmatic farmers and their healthy colleagues. It proved possible to determine a cut-off value that gave the analysis a specificity and sensitivity of 100%; the distinction between the two groups was highly significant (P < 0.0001). In the lymphocyte proliferation analysis, cow asthma was more closely associated with reactivity to BDA20 than to BEA. In the measurement of anti-BDA20 and anti-BEA IgG antibody levels, considerable overlap between the groups was observed, suggesting that these antibodies are not directly involved in cow allergy. When proteins associated with milk allergy were used as test reagents, no statistically significant differences could be observed between the groups, except for anti-casein IgE antibodies the level of which, however, overlapped considerably between the farmer groups.

CONCLUSION

These findings suggest that purified BDA20 is better than BEA for diagnosing cow asthma and that proteins associated with milk allergy are of only marginal significance in this disease.