Characterization of Ras k 1 a novel major allergen in Indian mackerel and identification of parvalbumin as the major fish allergen in 33 Asia-Pacific fish species.

BACKGROUND: Fish is a well-recognized cause of food allergy and anaphylaxis. The evolutionary and taxonomic diversity of the various consumed fish species pose a challenge in the identification and characterization of the major fish allergens critical for reliable diagnostics. Globally, fish is a rising cause of food allergy complicated by a large under-investigated variety of species as well as increasing global tourism and trade. This is the first comprehensive study on allergen profiles of heat-processed fish from Vietnam. OBJECTIVE: The aim of this study was to identify the major heat-stable allergens from frequently exported Asia-Pacific freshwater and marine fish and to characterize the major allergen parvalbumin (PV) from one of the most consumed and exported fish species from Asia, the Indian mackerel (Rastrelliger kanagurta). METHODS: Heated protein extracts from 33 fish species were separated by gel electrophoresis. PV isoforms were identified by immunoblotting utilizing 3 different PV-specific monoclonal and polyclonal antibodies and further characterized by mass spectrometry. IgE reactivity was investigated using sera from 21 patients with confirmed fish allergy. RESULTS: Heat-stable IgE-reactive PVs, with up to 5 isoforms per species, were identified in all 33 analysed fish species. In the Indian mackerel, 7 PV isoforms were identified by 2D-gel electrophoresis combined with mass spectrometric analyses. The amino acid sequence deduced from cDNA of the most expressed isoform showed a high identity (>90%) to PVs from 2 other mackerel species. CONCLUSIONS AND CLINICAL RELEVANCE: Different PVs were identified as the major heat-stable allergens in all 33 analysed freshwater and marine fish species from Vietnam, many of which are exported world-wide and 21 species that have never been investigated before. The Indian mackerel PV represents a novel fish allergen, now officially registered as Ras k 1. Improved diagnostics for fish allergy against Asia-Pacific species should be developed with focus on PV.

Allergenicity of bony and cartilaginous fish - molecular and immunological properties.

Allergy to bony fish is common and probably increasing world-wide. The major heat-stable pan-fish allergen, parvalbumin (PV), has been identified and characterized for numerous fish species. In contrast, there are very few reports of allergic reactions to cartilaginous fish despite widespread consumption. The molecular basis for this seemingly low clinical cross-reactivity between these two fish groups has not been elucidated. PV consists of two distinct protein lineages, α and ß. The α-lineage of this protein is predominant in muscle tissue of cartilaginous fish (Chondrichthyes), while ß-PV is abundant in muscle tissue of bony fish (Osteichthyes). The low incidence of allergic reactions to ingested rays and sharks is likely due to the lack of molecular similarity, resulting in reduced immunological cross-reactivity between the two PV lineages. Structurally and physiologically, both protein lineages are very similar; however, the amino acid homology is very low with 47-54%. Furthermore, PV from ancient fish species such as the coelacanth demonstrates 62% sequence homology to leopard shark α-PV and 70% to carp ß-PV. This indicates the extent of conservation of the PV isoforms lineages across millennia. This review highlights prevalence data on fish allergy and sensitization to fish, and details the molecular diversity of the two protein lineages of the major fish allergen PV among different fish groups, emphasizing the immunological and clinical differences in allergenicity.

EAACI Molecular Allergology User's Guide.

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

Characterizing the inhibitory action of zinc oxide nanoparticles on allergic-type mast cell activation.

The development of nanoparticles (NPs) for commercial products is undergoing a dramatic expansion. Many sunscreens and cosmetics now use zinc oxide (ZnO) or titania (TiO2) NPs, which are effective ultraviolet (UV) filters. Zinc oxide topical creams are also used in mild anti-inflammatory treatments. In this study we evaluated the effect of size and dispersion state of ZnO and TiO2 NPs, compared to "bulk" ZnO, on mast cell degranulation and viability. ZnO and TiO2 NPs were characterized using dynamic light scattering and disc centrifugation. Rat basophilic leukaemia (RBL-2H3) cells and primary mouse bone marrow-derived mast cells (BMMCs) were exposed to ZnO and TiO2 NPs of different sizes (25-200 nm) and surface coatings at concentrations from 1 to 200 µg/mL. The effect of NPs on immunoglobulin E (IgE)-dependent mast cell degranulation was assessed by measuring release of both ß-hexosaminidase and histamine via colorimetric and ELISA assays. The intracellular level of Zn(2+) and Ca(2+) ions were measured using zinquin ethyl ester and Fluo-4 AM fluorescence probes, respectively. Cellular viability was determined using the soluble tetrazolium-based MTS colorimetric assay. Exposure of RBL-2H3 and primary mouse BMMC to ZnO NPs markedly inhibited both histamine and ß-hexosaminidase release. This effect was both particle size and dispersion dependent. In contrast, TiO2 NPs did not inhibit the allergic response. These effects were independent of cytotoxicity, which was observed only at high concentrations of ZnO NPs, and was not observed for TiO2 NPs. The inhibitory effects of ZnO NPs on mast cells were inversely proportional to particle size and dispersion status, and thus these NPs may have greater potential than "bulk" zinc in the inhibition of allergic responses.

Shellfish allergy.

Seafood plays an important role in human nutrition and health. The growing international trade in seafood species and products has added to the popularity and frequency of consumption of a variety of seafood products across many countries. This increased production and consumption of seafood has been accompanied by more frequent reports of adverse health problems among consumers as well as processors of seafood. Adverse reactions to seafood are often generated by contaminants but can also be mediated by the immune system and cause allergies. These reactions can result from exposure to the seafood itself or various non-seafood components in the product. Non-immunological reactions to seafood can be triggered by contaminants such as parasites, bacteria, viruses, marine toxins and biogenic amines. Ingredients added during processing and canning of seafood can also cause adverse reactions. Importantly all these substances are able to trigger symptoms which are similar to true allergic reactions, which are mediated by antibodies produced by the immune system against specific allergens. Allergic reactions to 'shellfish', which comprises the groups of crustaceans and molluscs, can generate clinical symptoms ranging from mild urticaria and oral allergy syndrome to life-threatening anaphylactic reactions. The prevalence of crustacean allergy seems to vary largely between geographical locations, most probably as a result of the availability of seafood. The major shellfish allergen is tropomyosin, although other allergens may play an important part in allergenicity such as arginine kinase and myosin light chain. Current observations regard tropomyosin to be the major allergen responsible for molecular and clinical cross-reactivity between crustaceans and molluscs, but also to other inhaled invertebrates such as house dust mites and insects. Future research on the molecular structure of tropomyosins with a focus on the immunological and particularly clinical cross-reactivity will improve diagnosis and management of this potentially life-threatening allergy and is essential for future immunotherapy.

Determinants of asthma phenotypes in supermarket bakery workers.

While baker's asthma has been well described, various asthma phenotypes in bakery workers have yet to be characterised. Our study aims to describe the asthma phenotypes in supermarket bakery workers in relation to host risk factors and self-reported exposure to flour dust. A cross-sectional study of 517 supermarket bakery workers in 31 bakeries used a questionnaire, skin prick tests, and specific immunoglobulin E to wheat, rye and fungal alpha-amylase and methacholine challenge testing. The prevalence of probable occupational asthma (OA, 13%) was higher than atopic (6%), nonatopic (6%) and work-aggravated asthma (WAA, 3%) phenotypes. Previous episodes of high exposure to dusts, fumes and vapours causing asthma symptoms were more strongly associated with WAA (OR 5.8, 95% CI 1.7-19.2) than OA (2.8, 1.4-5.5). Work-related ocular-nasal symptoms were significantly associated with WAA (4.3, 1.3-13.8) and OA (3.1, 1.8-5.5). Bakers with OA had an increased odds ratio of reporting adverse reactions to ingested grain products (6.4, 2.0-19.8). OA is the most common phenotype among supermarket bakery workers. Analysis of risk factors contributes to defining clinical phenotypes, which will guide ongoing medical surveillance and clinical management of bakery workers.

Differential requirements for interleukin (IL)-4 and IL-13 in protein contact dermatitis induced by Anisakis.

BACKGROUND: Exposure to antigens of the fish parasite Anisakis is associated with the development of protein contact dermatitis in seafood-processing workers. Understanding the basic mechanisms controlling allergic sensitization through the skin is critical for designing therapies that will prevent the progression of allergic disease. OBJECTIVE: To investigate the roles of interleukin (IL)-4, IL-13 and the IL-4Ralpha in both local skin pathology and systemic sensitization following epicutaneous exposure to Anisakis proteins. METHODS: BALB/c wild-type (WT) mice and mice deficient in IL-4, IL-13 or IL-4 and IL-13, as well as mice with cell-specific impairment of IL-4Ralpha expression, were sensitized to Anisakis antigen by repeated epicutaneous application of Anisakis extract. Following this sensitization, skin pathology was recorded and systemic responses were investigated. Intravenous challenge with Anisakis extract was performed to test for the development of biologically relevant systemic sensitization. RESULTS: In WT mice, epicutaneous sensitization with Anisakis larval antigens induced localized inflammation, epidermal hyperplasia, production of T(H)2 cytokines, antigen-specific IgE and IgG1. Intravenous challenge of sensitized mice resulted in anaphylactic shock. Interestingly, IL-13 deficient mice failed to develop epidermal hyperplasia and inflammation, whilst anaphylaxis was reduced only in strains deficient either in IL-4 only, or deficient in IL-4 and IL-13 concurrently, as well as in mice deficient in IL-4Ralpha or with impaired IL-4Ralpha expression on CD4(+) T cells. CONCLUSIONS: Interleukin-13 plays a central role in protein contact dermatitis associated with repeated epicutaneous exposure to Anisakis extract, whereas IL-4 drives systemic sensitization and resultant anaphylactic shock.

Risk factors for allergy due to the two-spotted spider mite (Tetranychus urticae) among table grape farm workers.

BACKGROUND: Recent studies have reported an increased prevalence of respiratory symptoms among farm workers. The aim of this study was to identify risk factors associated with spider mite allergy among table grape farm workers. METHODS: A cross-sectional study of 207 workers in table grape farms was conducted. Skin prick tests used extracts of 8 common aeroallergens, grape mould (Botrytis cinerea) and Tetranychus urticae. Specific IgE to T. urticae was quantified using ImmunoCAP (Phadia). Erythrocyte cholinesterase levels were determined using the Test-mate ChE Cholinesterase Test System (model 460). RESULTS: The average duration of employment of workers was 10 years and 12% were pesticide crop sprayers. Work-related wheeze (26%), ocular-nasal (24%) and urticaria/skin symptoms (14%) were more prevalent in the orchards. The prevalence of sensitization (skin prick test) was highest to T. urticae (22%) followed by house dust mite (16%), with 25% being atopic. The prevalence of allergy to T. urticae (skin reactivity and work-related symptoms) was 9.5%, with respiratory allergy (6%) more common than skin allergy (3%). Work-related ocular-nasal (OR = 4.9) and skin (OR = 3.7) symptoms were more commonly reported by pesticide crop sprayers. Workers with T. urticae-allergic rhino-conjunctivitis and probable asthma were more likely to be atopic, spray pesticides and have low (<30 U/g hemoglobin) erythrocyte cholinesterase levels. CONCLUSIONS: This study demonstrated that spider mite, T. urticae, is an important outdoor allergen among table grape farm workers. The increased risk of spider mite allergy appears to be related to high pesticide exposure among crop sprayers.

Environmental exposure characterization of fish processing workers.

BACKGROUND: Aerosolization of seafood and subsequent inhalation, during processing is a potential high-risk activity for allergic respiratory disease. OBJECTIVES: To quantify total thoracic particulate, protein concentration and specific fish (pilchard, anchovy) antigen concentrations in fish processing plants; to determine the correlation between these exposure metrics; and to identify the major determinants of variability and the optimal grouping strategies for establishing dose-response relationships for fish antigen exposures. METHODS: Exposure assessments were conducted on randomly selected individuals within each of the identified 'exposure groups' (EGs) in two fish processing factories. Personal time-integrated sampling was conducted with a thoracic fraction sampler and analysed for particulate mass, total protein and specific fish antigens. Exposure metrics were developed on the basis of individually measured exposures and average levels of these personal samples within EGs. The main components of the exposure variability were determined using ANOVA techniques. RESULTS: A total of 198 full-shift personal aerosol samples were collected and analysed. Twenty-two percent of the samples were below the limit of detection (LOD) for pilchard and 23% for anchovy assays. Personal sampling revealed wide variations across EGs in arithmetic mean concentrations of thoracic particulate 0.61 mg m(-3) (range: LOD-11.3), total protein 0.89 microg m(-3) (LOD-11.5), pilchard antigen 150 ng m(-3) (LOD-15 973) and anchovy antigen 552 ng m(-3) (LOD-75 748) levels. The fishmeal loading and bagging sections of both plants showed consistently high thoracic particulate mass (0.811-2.714 mg m(-3)), total protein (0.185-1.855 microg m(-3)), pilchard antigen (538-3288 ng m(-3)) and anchovy antigen (1708-15 431 ng m(-3)). The a priori strategy that grouped workers according to EGs produced reasonably satisfactory summary exposure metric statistics. An alternative grouping strategy based on department revealed comparable elasticity (exposure contrast). While the correlation between the log-transformed thoracic particulate mass and fish antigen concentrations were generally modest (Pearson's r = 0.32-0.35, P < 0.001), a high correlation was found between pilchard and anchovy antigen concentrations (Pearson's r = 0.71, P < 0.001). Models using factory and department grouping strategies accounted for a significant portion of the variability (adjusted r(2) = 0.18, P = 0.043) in pilchard antigen levels. Grouping strategies using a combination of factory and department yielded the highest degree of elasticity for thoracic particulate (0.38) and pilchard antigen (0.42) levels. CONCLUSIONS: Workers involved in bony fish processing are at risk of inhaling aerosols containing pilchard and anchovy fish antigens. Antigen exposures are highest during fishmeal production and bagging. Grouping strategies based on department and factory may provide a more efficient approach than a priori classification of EGs for evaluating fish antigen exposures.

Occupational allergy in laboratory workers caused by the African migratory grasshopper Locusta migratoria.

BACKGROUND: Recent reports of fatal asthma cases associated with swarms of locusts affecting African countries have highlighted the importance of this insect in causing asthma morbidity and mortality. However, only limited information is available about the allergic health outcomes such as asthma and its determinants in exposed individuals. In this study, workers exposed to the African migratory locust Locusta migratoria were evaluated for allergic health outcomes as well as the nature of the offending allergens. METHODS: Ten scientists and technicians exposed to locusts in a laboratory were investigated for locust-related allergy using questionnaires and immunological tests. The presence of allergy was determined by quantification of specific IgE and IgG to L. migratoria using the UniCAP system and via skin-prick testing (SPT). The allergens were characterized by Western blot and ImmunoCAP inhibition assays. RESULTS: Six of the 10 workers experienced symptoms ranging from urticaria and rhinoconjuctivitis to asthma. Seven individuals demonstrated sensitivity on SPT and five had specific IgE antibodies to L. migratoria. Significant cross-reactivity was demonstrated for allergens in the locust faeces, body and wings but not to cockroach allergens. Novel allergens with molecular weights of approximately 70 kDa were identified in locust wings, which are distinctly different from other known allergen sources from locusts. CONCLUSION: Exposure to L. migratoria allergens is a potential sensitizer in exposed individuals. Raised levels of locust-specific IgE can be readily quantified. The wings of this insect species have been identified as a novel allergen source.

Immunohistochemical localization of CYP1A, vitellogenin and Zona radiata proteins in the liver of swordfish (Xiphias gladius L.) taken from the Mediterranean Sea, South Atlantic, South Western Indian and Central North Pacific Oceans.

Cytochrome P4501A (CYP1A) monoxygenase, vitellogenin (Vtg) and Zona radiata proteins (Zrp) are frequently used as biomarkers of fish exposure to organic contaminants. In this work, swordfish liver sections obtained from the Mediterranean Sea, the South African coasts (South Atlantic and South Western Indian Oceans) and the Central North Pacific Ocean were immunostained with antisera against CYP1A, Zrp, and Vtg. CYP1A induction was found in hepatocytes, epithelium of the biliary ductus and the endothelium of large blood vessels of fish from the Mediterranean Sea and South African waters, but not from the Pacific Ocean. Zrp and Vtg were immunolocalized in hepatocytes of male swordfish from the Mediterranean Sea and from South African waters. Plasma Dot-Blot analysis, performed in Mediterranean and Pacific specimens, revealed the presence of Zrp and Vtg in males from Mediterranean but not from Pacific. These results confirm previous findings about the potential exposure of Mediterranean swordfish to endocrine, disrupting chemicals and raise questions concerning the possible presence of xenobiotic contaminants off the Southern coasts of South Africa in both the South Atlantic and South Western Indian Oceans.

Occupational allergies in the seafood industry--a comparative study of Australian and South African workplaces.

Although seafood allergy due to ingestion is commonly observed in clinical practice, the incidence of seafood allergies in general and more specifically in the occupational setting in Australia is largely unknown. The work practices, occupational health services and allergic health problems in 140 seafood processing workplaces in Australia were examined and compared to previous studies in South Africa. A cross-sectional employer-based survey design was used to conduct the study in both countries. In the South African study a response rate of 60% (n = 41) was obtained, compared to a response rate of 18% (n = 140) in Australia. The most common seafood processed by workplaces in South Africa was finfish (76%) and rock lobster (34%). Similarly in Australia, finfish (34%) was the most frequently handled seafood. However, processing of prawns (24%) and oysters (21%) was more common in Australia. Common work processes in South Africa involved freezing (71%), cutting/filleting (63%) and degutting (58%) procedures. Similar processes were followed in Australian industries with the exception of shucking of oysters, particularly common in the aquaculture industries. About half of the workplaces in both countries provided an occupational health service and medical surveillance of workers. However, none of the workplaces in South Africa and only 9% of the workplaces in Australia had industrial hygiene programs for seafood aerosols in place. In both countries positive trends were observed between the size of the workforce and the provision of occupational health services (p<0.005). Similarly, skin rash accounted for highest of all reported health problems (78-81%) followed by asthmatic symptoms (7-10%) and other non-specific allergic symptoms (9-15%) in both countries. Most workplaces reported the annual prevalence of work-related symptoms to be less than 5%. In Australia 7% of respondents in workplaces reported workers having left their workplace due to work-related allergic problems. Despite a low response rate of contacted companies in Australia, there were great similarities between the two countries suggesting that there is a significantly elevated prevalence of work related allergic symptoms in both countries. Unexpectedly, mollusc processing was more common in Australia although the occupational health related effects among exposed workers has previously not been investigated in detail and merits further study. It is recommended that further epidemiological studies focus on seafood exposure in Australia and identify specific risk factors for sensitisation.

Occupational seafood allergy: a review.

BACKGROUND: Recent years have seen increased levels of production and consumption of seafood, leading to more frequent reporting of allergic reactions in occupational and domestic settings. This review focuses on occupational allergy in the fishing and seafood processing industry. REVIEW: Workers involved in either manual or automated processing of crabs, prawns, mussels, fish, and fishmeal production are commonly exposed to various constituents of seafood. Aerosolisation of seafood and cooking fluid during processing are potential occupational situations that could result in sensitisation through inhalation. There is great variability of aerosol exposure within and among various jobs with reported allergen concentrations ranging from 0.001 to 5.061(microg/m(3)). Occupational dermal exposure occurs as a result of unprotected handling of seafood and its byproducts. Occupational allergies have been reported in workers exposed to arthropods (crustaceans), molluscs, pisces (bony fish) and other agents derived from seafood. The prevalence of occupational asthma ranges from 7% to 36%, and for occupational protein contact dermatitis, from 3% to 11%. These health outcomes are mainly due to high molecular weight proteins in seafood causing an IgE mediated response. Cross reactivity between various species within a major seafood grouping also occurs. Limited evidence from dose-response relations indicate that development of symptoms is related to duration or intensity of exposure. The evidence for atopy as a risk factor for occupational sensitisation and asthma is supportive, whereas evidence for cigarette smoking is limited. Disruption of the intact skin barrier seems to be an important added risk factor for occupational protein contact dermatitis. CONCLUSION: The range of allergic disease associated with occupational exposure to crab is well characterised, whereas for other seafood agents the evidence is somewhat limited. There is a need for further epidemiological studies to better characterise this risk. More detailed characterisation of specific protein antigens in aerosols and associated establishment of dose-response relations for acute and chronic exposure to seafood; the respective roles of skin contact and inhalational exposure in allergic sensitisation and cross reactivity; and the contribution of host associated factors in the development of occupational seafood allergies are important areas for future research.

Seafood processing in South Africa: a study of working practices, occupational health services and allergic health problems in the industry.

The work practices, occupational health services and allergic health problems among workplaces which process seafood in Western Cape province of South Africa were examined. A cross-sectional study was conducted among 68 workplaces that were sent a self-administered postal survey questionnaire. Workplaces reporting a high prevalence of work-related symptoms associated with seafood exposure were also inspected. Forty-one (60%) workplaces responded to the questionnaire. The workforce consisted mainly of women (62%) and 31% were seasonal workers. Common seafoods processed were bony fish (76%) and rock lobster (34%). Major work processes involved freezing (71%), cutting (63%) and degutting (58%). Only 45% of workplaces provided an on-site occupational health service and 58% of workplaces conducted medical surveillance. Positive trends were observed between workplace size and activities such as occupational health service provision (P = 0.002), medical surveillance programmes (P = 0.055) and reporting work-related symptoms (P = 0.016). None of the workplaces had industrial hygiene surveillance programmes to evaluate the effects of exposure to seafood. Common work-related symptoms included skin rashes (78%), asthma (7%) and other non-specific allergies (15%). The annual prevalence of work-related skin symptoms reported per workplace was substantially higher for skin (0-100%) than for asthmatic (0-5%) symptoms. The relatively low prevalence of employer-reported asthmatic symptoms, when compared to epidemiological studies using direct investigator assessment of individual health status, suggests likely under-detection. This can be attributed to under-provision and under-development of occupational health surveillance programmes in workplaces with less than 200 workers. This is compounded further by the lack of specific statutory guidelines for the evaluation and control of bio-aerosols in South African workplaces.

Characteristics of hypersensitivity reactions and identification of a unique 49 kd IgE-binding protein (Hal-m-1) in abalone (Haliotis midae).

BACKGROUND: There is a paucity of published data on the clinical presentation and the nature of the allergens involved in hypersensitivity to mollusks. This study reports the clinical and immunologic findings in 38 patients with reported immediate and delayed adverse reactions to abalone (Haliotis midae, Class Gastropoda). METHODS: Patients were recruited as part of a South African seafood allergy survey. Allergic symptoms were assessed by a self-administered questionnaire. A total of 38 patients with abalone sensitivity were recruited. Specific IgE responses to abalone and other mollusks were studied by using RAST and inhibition ELISAs. Skin prick tests and lymphocyte proliferation assays were also performed on several of the subjects. Allergenic components of Haliotis midae were identified with Western blotting. RESULTS: Twenty five of the 38 patients in the study were first seen with immediate symptoms, and 13 had delayed reactions. Seventeen of the sera tested were RAST positive. Skin prick tests responses with abalone extract were positive in all subjects with positive RAST responses (n = 8) and in 6 of 13 subjects with negative RAST responses. Five of the subjects with positive RAST responses had positive results on Western blotting and demonstrated binding to two major allergens with molecular weights of 38 and 49 kd. The 49 kd IgE-binding protein has been designated as Hal-m-1. CONCLUSIONS: Abalone allergens are heat-stable proteins with molecular weights of 38 and 49 kd, later designated as Hal-m-1 according to International Union of Immunological Societies allergen nomenclature regulation. Our studies indicate a clear clinical and immunologic heterogeneity in patients reactive to abalone.