Snow crab allergy and asthma among Greenlandic workers--a pilot study.

OBJECTIVES: To study snow crab sensitization, occupational allergy and asthma in the snow crab industry in Greenland, as high rates have been found in Canada, but no reports have emerged from the same industry in Greenland. STUDY DESIGN: Pilot survey. METHODS: Twenty workers (19 of Inuit and 1 of other origin) in a snow crab (Chionoecetes opilio) and Atlantic shrimp (Pandalus borealis) processing plant in Greenland were assessed with skin prick tests (SPTs) with common aeroallergens and specific allergens from snow crab and shrimp extracts, spirometry, blood sampling for total IgE and specific IgE determination. Eighteen workers contributed a questionnaire-based medical interview. RESULTS: Positive skin prick test reactions were common to snow crab (40%) and shrimp (20%). Specific IgE to snow crab were positive in 4 workers (21%). Two workers had elevated total IgE levels. Symptoms suggestive of asthma were common (45%). Work-related symptoms of skin rash, rhinitis, and/or conjunctivitis were reported by 50%, and symptoms from the lower airways by 39%. Combining history of work-related symptoms with results from specific SPTs and/or specific IgE determination suggested that 11 and 22% of workers suffered from probable and possible occupational asthma, respectively, whereas 22% had possible occupational dermatitis or rhinitis. CONCLUSIONS: Greenlander Inuit do not appear to be protected against sensitization to snow crab or shrimp when occupationally exposed to these. This pilot study suggests that occupational allergy and asthma may be as common a problem in Greenlandic workers as in Canadian.

Identification of crab proteins that elicit IgE reactivity in snow crab-processing workers.

BACKGROUND: The expanding snow crab-processing industry has resulted in increased numbers of workers at risk of occupational allergy. OBJECTIVE: Our study is to identify relevant allergenic proteins in cooked snow crab meat (CM) and crab water (CW) used for cooking for improved remediation, diagnosis, and treatment. METHODS: Extracts were prepared from CM extracts, CW extracts, and an air-filter collection near the crab cooker. Of the 207 workers, 24 with the highest IgE antibody reactivity to CM and CW extracts, as determined by using RASTs, were tested for reactivity to nitrocellulose membranes containing CM and CW proteins separated with SDS-PAGE. A 3-serum pool was similarly incubated against nitrocellulose-bound proteins from air samples collected near the crab cooker. RESULTS: Of the 207 sera tested, 27 and 39 sera exhibited positive IgE antibody reactivity (>or=2%) to CM and CW extracts, respectively. Twenty-two of 24 sera with the highest RAST activity (>or=3.5% binding) demonstrated IgE binding to multiple proteins (13.6-50 kd). A majority of the sera reacted to 4 proteins: 79% and 71% to a 34.0-kd protein, 79% and 42% to a 25-kd protein, 67% and 71% to an 18.5-kd protein, and 75% to a 14.4-kd protein in both CM and CW extracts, respectively. The pool of IgE-positive sera blotted against the air-filter extract reacted to 14.4-, 18.5-, 34.0-, 43.2-, and 50-kd proteins present in both crab extracts. CONCLUSION: Four major IgE-reactive proteins were identified in CM extracts, CW extracts, and air-filter eluate. Analysis of any potential association of protein reactivity with disease suggested crab proteins at 34.0 and 14.4 kd might be more relevant.

New insights into seafood allergy.

PURPOSE OF REVIEW: Seafood plays an important role in human nutrition worldwide, sustained by international trade of a variety of new seafood products. Increased production and consumption have resulted in more frequent reports of adverse reactions, highlighting the need for more specific diagnosis and treatment of seafood allergy. This review discusses recent literature in this field. RECENT FINDINGS: The most recent prevalence data from Asia highlight seafood as a significant sensitizer in up to 40% of children and 33% of adults. Furthermore, the demonstration of species-specific sensitization to salt-water and fresh-water prawns and processed prawn extract should improve diagnosis. Studies on humans demonstrated for the first time that biologically active fish allergens can be detected in serum samples as early as 10 min after ingestion. These studies highlight that minute amounts of ingested seafood allergens can quickly trigger allergic symptoms; also, inhaled airborne allergens seem to induce sensitization and reactions. In the past 2 years, over 10 additional seafood allergens have been characterized. Allergen-specific detection assays in food products are available for crustacean tropomyosin; however, many specific mollusk and some fish allergens are not readily identified. SUMMARY: Although cross-reactivity between crustacean and mollusks as well as mites is demonstrated, the often poor correlation of IgE reactivity and clinical symptoms calls for more detailed investigations. The recent development of hypoallergenic parvalbumin from carp could form the basis for safer vaccination products for treatment of fish allergy. Molecular characterization of more universal marker allergens for the three major seafood groups will improve current component-resolved clinical diagnosis and have a significant impact on the management of allergic patients, on food labeling and on future immunotherapy for seafood allergy.

Utility of animal models for predicting human allergenicity.

The biochemical characterization of protein structures has led to a better understanding of allergens, their structure/function relationship, and can be very powerful in identifying protein sequences with significant structural similarity to known allergens. However, for scientists, regulators and food manufacturers there exists a need for acquiring additional data on potential allergenicity of proteins, particularly, biotechnology derived molecules in food products for which minimal or no prior human exposure information is available. Since human exposure testing, while direct, is unacceptable, understanding allergy in animals has been used to investigate the allergic response on a molecular level as well as test the potential in vivo allergenicity of food proteins. Rodents seem to be the most likely candidate for assessing allergenicity. For development of an animal test system for allergenicity characterization and testing, a number of criteria are required for qualification for a model of human allergy including acceptable immunization protocols, allergic response measurements, and for standardization and validation of materials and procedures. If an animal test system can minimally provide a basis for measuring the relative physiological response to known allergens, this should be enough to establish a model that produces a relative measure of potential allergenicity. Our article will consider development of an adequate animal model for allergenicity determination that can be validated as a tool in safety assessments.

Prevalence of IgE reactivities in mold-allergic subjects to commercially available fungal enzymes.

Fungi are important aeroallergens. However, fungal allergen sources of consistent quality for clinical testing are not readily available. Because some allergens have been identified as enzymes, we assessed the prevalence of IgE reactivity to commercially available fungal enzymes. The purpose of this study was to determine IgE antibody reactivity by radioallergosorbent assay (RAST) to commercially available fungal enzymes in mold-allergic individuals. Sera from 20 subjects with symptoms of respiratory allergies and skin test reactivity to 2 or more fungal allergens (4 conidial [imperfecti] fungi and/or 8 basidiomycetes) were selected. Controls were six atopic individuals with neither history of fungal allergy nor skin test reactivity to fungi. Seventeen commercial fungal enzymes were used as antigens to evaluate the subjects' IgE antibody reactivity by RAST. Sera from most fungus-allergic individuals showed substantial IgE antibody reactivity to enzymes; control sera showed little or no reactivity. The mean reactivity to all commercial enzymes of all subjects tested was RAST > or = 3% with only one exception. The most reactive fungal enzymes were invertase (bakers' yeast, Saccharomyces cerevisiae), cellulase (Trichoderma viride), and glucosidase (brewers yeast, S. cerevisiae) with mean binding of 14.6, 9.5, and 8.8%, respectively. Using RAST results with a combination of four enzymes from S. cerevisiae (brewers yeast glucosidase, bakers' yeast maltase, invertase, and invertase V), a sensitivity of 100% was shown for detecting mold-allergic patients. The studies suggest that fungal enzymes may be useful source materials for the identification of fungal allergens and may also provide readily available source materials to produce improved diagnostic and therapeutic reagents.

Reduced allergenic potency of VR9-1, a mutant of the major shrimp allergen Pen a 1 (tropomyosin).

The major shrimp allergen, tropomyosin, is an excellent model allergen for studying the influence of mutations within the primary structure on the allergenic potency of an allergen; Pen a 1 allows systematic evaluation and comparison of Ab-binding epitopes, because amino acid sequences of both allergenic and nonallergenic tropomyosins are known. Individually recognized IgE Ab-binding epitopes, amino acid positions, and substitutions critical for IgE Ab binding were identified by combinatorial substitution analysis, and 12 positions deemed critical were mutated in the eight major epitopes. The mutant VR9-1 was characterized with regard to allergenic potency by mediator release assays using sera from shrimp-allergic subjects and sera from BALB/c, C57BL/6J, C3H/HeJ, and CBA/J mice sensitized with shrimp extract using alum, cholera toxin, and Bordetella pertussis, as adjuvants. The secondary structure of VR9-1 was not altered; however, the allergenic potency was reduced by 90-98% measuring allergen-specific mediator release from humanized rat basophilic leukemia (RBL) cells, RBL 30/25. Reduced mediator release of RBL-2H3 cells sensitized with sera from mice that were immunized with shrimp extract indicated that mice produced IgE Abs to Pen a 1 and to the same epitopes as humans did. In conclusion, data obtained by mapping sequential epitopes were used to generate a Pen a 1 mutant with significantly reduced allergenic potency. Epitopes that are relevant for human IgE Ab binding are also major binding sites for murine IgE Abs. These results indicate that the murine model might be used to optimize the Pen a 1 mutant for future therapeutic use.

Detection of fish antigens aerosolized during fish processing using newly developed immunoassays.

BACKGROUND: Aerosolization of fish proteins during seafood processing has been identified as a potential route for allergic sensitization and occupational asthma among workers involved in high-risk activities. The aim of this study was to develop immunological assays for the quantification of aerosolized fish antigens in a fish-processing factory. METHODS: Polyclonal antibodies to the main fish species processed in the factory (anchovy and pilchard) were generated in rabbits and compared by ELISA inhibition assay and immunoblotting. These antisera were utilized to develop ELISA assays for the detection of fish antigens. The ELISA inhibition assays were evaluated by analyzing environmental air samples collected from three areas in a fish-processing factory: pilchard canning, fish meal production and lobster processing. RESULTS: By immunoblotting, the rabbit polyclonal antibodies demonstrated IgG antibody binding patterns comparable with IgE antibodies of fish-sensitized patients, particularly in regard to the major fish allergens parvalbumins. The sensitivity of the fish-specific ELISA assays developed was 0.5 microg/ml. The ELISA inhibition assays were able to differentiate between the two different fish species of interest but did not recognize a crustacean species. Notable differences in exposure levels to canned pilchard and anchovy antigens were demonstrated in the three different working areas of the factory, with assays having a detection limit as low as 105 ng/m(3). CONCLUSION: These ELISA-based assays are sensitive and specific to quantify differential exposure levels to fish antigens produced during fish processing, making it possible to investigate exposure-disease response relationships among workers in this industry.

Fish and shellfish allergy.

Fish and shellfish are important in the American diet and economy. Nearly $27 billion are spent each year in the United States on seafood products. Fish and shellfish are also important causes of food hypersensitivity. In fact, shellfish constitute the number one cause of food allergy in the American adult. During the past decade, much has been learned about allergens in fish and shellfish. The major allergens responsible for cross-reactivity among distinct species of fish and amphibians are parvalbumins. The major shellfish allergen has been identified as tropomyosin. Many new and important potential cross-reacting allergens have been identified within the fish family and between shellfish, arachnids, and insects. Extensive research is currently underway for the development of safer and more effective methods for the diagnosis and management of fish and shellfish hypersensitivity.

Genetic modification of food allergens.

OBJECTIVE: To review allergen risk evaluation for genetically modified foods and our ability to predict protein allergenicity, methods that are being used to develop foods with reduced allergenic activity, and clinical aspects relative to assessing potentially allergic patients. DATA SOURCES: Information was identified using the MEDLINE database for governmental, international, and industry organizations that have considered possible unintended health effects such as food allergy and how they can be avoided. DATA SELECTION: The author's knowledge of the field was used to select articles for inclusion in this review. RESULTS: Organizations have created a decision process that has generally been successful in avoiding development of products that cause allergic reactions. Since some proteins expressed do not have any history of human exposure, risk evaluation may be more of a challenge for them. Biotechnology has also been used to try to develop foods with reduced allergenicity, and in future years such products should yield safer foods. CONCLUSIONS: Allergy risk evaluation for known allergens and genetically modified foods appears to be reasonable and provides assurance of food safety. Allergenicity evaluation of novel proteins is a more complicated process that needs to be and will be improved as our knowledge of food allergens increases. Biotechnology can be used to produce safer and healthier foods; for example, allergenicity of some foods may be reduced through biotechnology. The role of the health care professional in assessing allergic reactions to genetically modified foods is essential and should play a greater role in the interaction of consumers, industry, and regulators.

Seafood allergy.

PURPOSE OF REVIEW: Given the importance and prevalence of seafood in our economy and diet, interest in the adverse effects of seafood-induced allergic reactions has increased both in the lay population and the scientific arena. The purpose for this review article is to provide an overview and discussion of current seafood-allergy research. RECENT FINDINGS: Current research has produced the discovery of new seafood allergens as well as a better understanding of the interactions of allergens with the host, and the relationships of IgE antibodies with specific allergens. Crossreactivity of similar molecules from seafood and nonseafood sources provides a better understanding of an allergen's role in seafood allergy and a basis to improve patient identification and treatment. SUMMARY: Findings in recent literature show potential for more precise diagnosis and safer, more effective treatment of seafood allergies.

Prevalence of crab asthma in crab plant workers in Newfoundland and Labrador.

OBJECTIVES: The aim of the study was to determine the prevalence of snow crab sensitisation and occupational asthma. STUDY DESIGN: Prevalence study of symptoms, pulmonary function testing and allergy testing to crab was conducted in four crab plants of different design in Newfoundland and Labrador, Canada. METHODS: Plants workers in four crab plants were interviewed and offered skin testing, RAST, pulmonary function testing and peak flow monitoring before and during crab processing. RESULTS: 38% (n=78) had atopy. 18% (n=39) had certain or highly probable crab asthma. The prevalence of sensitisation in different crab plants varied from 50% (n=19) to 15% (n=16) and the prevalence of certain or highly probable crab asthma varied from 50% (n=19) to 9% (n=3). CONCLUSION: Crab asthma and sensitisation to snow crab is a major health problem for snow crab plant workers in Newfoundland and Labrador.

New approaches for treatment of peanut allergy: chances for a cure.

Food allergy is a major cause of life-threatening hypersensitive reactions. Food-induced anaphylaxis is the most common reason for a person to present to the emergency department for treatment of the anaphylactic reaction. Avoiding the allergenic food is the only currently available method for sensitized patients to prevent further reactions. Strict avoidance of specific foods is accepted treatment of food-induced allergic reactions but is often an unrealistic therapeutic strategy for the treatment and prevention of food-induced hypersensivity reactions for the many reasons. Desirable therapeutic strategies for the treatment and prevention of the food allergies must be safe, relatively inexpensive, and easily administered. Recent advances in the understanding of the immunological mechanisms underlying allergic disease and better characterization of food allergens have greatly expanded the potential therapeutic option for future use. Several different forms of immunodulatory therapies are currently under investigation: peptide immunotherapy, mutated protein immunotherapy, allergen DNA immunization, vaccination with immunostimulatory DNA sequences, and anti-immunoglobulin E-therapy.

Molecular basis of arthropod cross-reactivity: IgE-binding cross-reactive epitopes of shrimp, house dust mite and cockroach tropomyosins.

BACKGROUND: Shrimp may cross-react with other crustaceans and mollusks and nonedible arthropods such as insects (cockroach and chironomids), arachnids (house dust mites) and even nematodes. Since the muscle protein tropomyosin has been implicated as a possible cross-reacting allergen, this study characterized the IgE-binding epitopes in shrimp tropomyosin, Pen a 1, that cross-react with other allergenic invertebrate tropomyosins in house dust mites (Der p 10, Der f 10) and cockroaches (Per a 7). Pen a 1-reactive sera from shrimp-allergic subjects were used to evaluate the effect on IgE binding of different amino acid substitutions in Pen a 1 epitopes based on homologous sequences in Per a 7 and Der p 10/Der f 10. METHODS: Peptides were synthesized spanning the length of Pen a 1 IgE-binding epitopes and amino acid substitutions were performed based on homologous amino acid sequences from Per a 7 and Der p 10/Der f 10. RESULTS: 7/8 individually recognized Pen a 1 epitopes (2, 3a, 3b, 4, 5a, 5b and 5c) had an identical amino acid sequence with lobster allergen, Hom a 1, 4/8 (3a, 3b, 4 and 5a) with Der p 10 and Der f 10, and 5/8 (2, 3a, 3b, 4 and 5a) with Per a 7. In addition, even homologous regions of other arthropod tropomyosins that differ in one or more amino acids from the sequences of Pen a 1 epitopes are still recognized by shrimp-allergic IgE antibodies. In total, shrimp-allergic sera recognize 6/8 peptides homologous to Pen a 1 epitopes in Per a 7, 7/8 in Der p 10/Der f 10, and 7/8 epitopes in Hom a 1. CONCLUSIONS: The IgE recognition by shrimp-allergic individuals of identified and/or similar amino acid sequences homologous to Pen a 1 epitopes in mite, cockroach and lobster tropomyosins are the basis of the in vitro cross-reactivity among invertebrate species. Based on amino acid sequence similarity and epitope reactivity, lobster tropomyosin has the strongest and cockroach the least cross-reactivity with shrimp. The clinical relevance of these cross-reactivities in developing allergic reactions to different arthropods needs to be determined.

Current understanding of food allergens.

Food allergies are IgE-mediated immunological reactions; this distinguishes them from other adverse reactions to foods. Most (>90%) of the recognized food allergies are generally thought to be caused by eight foods or food groups. A number of factors can affect food allergy development, including diet and culture, route of exposure, processing, cooking, and digestion. In addition, it is thought that the properties of certain food proteins render them more likely to be allergenic than other proteins. Most food allergens are major proteins, polyvalent molecules with at least two or more IgE-binding sites, and are recognized as foreign molecules (hence immunogenic). A number of major food allergens have been recently characterized, and amino acid sequences determined. Tropomyosin is the only major allergen of shrimp. A number of IgE-binding epitopes have been identified in this molecule, though they may vary from one shrimp-allergic individual to another. Single amino acid substitutions within epitopes based on that of homologous, nonreactive tropomyosins can substantially enhance or abolish IgE antibody binding. Using the accumulated knowledge of food allergen protein structure, the allergenicity of novel proteins to which there has been no prior human exposure has been assessed. This has been based primarily on the lability or resistance of a protein to enzymatic degradation. Clearly, further criteria must be developed to refine this process. In this regard, the development of animal models that have been sufficiently validated as surrogates of human IgE antibody responses is needed for more precise assessment of the allergenic potential of proteins.

Occupational reactions to foods.

The spectrum of occupational diseases most commonly seen in the food industry includes occupational asthma, rhinitis, conjunctivitis, dermatitis, and hypersensitivity pneumonitis. Occupational asthma represents between 3% and 20% of all asthma cases and is the most common form of occupational lung disease. Occupational skin diseases may represent between 10% and 15% of all occupational diseases, and they have significant economic impact. Hypersensitivity pneumonitis affects the food industry, with farmer's lung representing a common form of the disease. Each of these diseases may have serious and potentially irreversible effects on the health of a farmer, food processor, or food preparer, even after removal of the offending exposure.

Microarrayed allergen molecules: diagnostic gatekeepers for allergy treatment.

Type I allergy is an immunoglobulin E (IgE)-mediated hypersensitivity disease affecting more than 25% of the population. Currently, diagnosis of allergy is performed by provocation testing and IgE serology using allergen extracts. This process defines allergen-containing sources but cannot identify the disease-eliciting allergenic molecules. We have applied microarray technology to develop a miniaturized allergy test containing 94 purified allergen molecules that represent the most common allergen sources. The allergen microarray allows the determination and monitoring of allergic patients' IgE reactivity profiles to large numbers of disease-causing allergens by using single measurements and minute amounts of serum. This method may change established practice in allergy diagnosis, prevention, and therapy. In addition, microarrayed antigens may be applied to the diagnosis of autoimmune and infectious diseases.