A Clinical and Immunological Study of Allergy to Hen's Egg White

The occurrence of proteins cross-reacting with allergens in hen's egg white was studied in turkey, duck, goose and seagull egg whites, in hen egg yolk, and in hen and chicken sera and flesh. The study was based upon quantitative immunoelectrophoretic techniques. The different egg whites were all found to contain proteins cross-reacting with most of the allergens in hen's egg white, but the degree of cross-reactivity varied considerably among the various egg whites. All egg whites contained proteins able to bind human IgE-antibody in the sera of patients with allergy to hen's egg white. Several proteins cross-reacting with allergens in hen's egg white were also detected in egg yolk and in hen and chicken sera and flesh. Clinical implications of the results are discussed.     

Egg white proteins as inhalant allergens associated with baker's asthma

BACKGROUND: Bakery workers may develop IgE-mediated allergy to liquid and aerosolized hen's egg proteins that are commonly used in the baking and confectionery industries. METHODS: We studied four bakery workers who had work-related allergic respiratory symptoms upon exposure to egg aerosols. The causative role of egg proteins in their respiratory symptoms was investigated by immunologic and specific inhalation challenge (SIC) tests. RESULTS: Skin prick tests to egg white extract and to lysozyme gave positives responses in all the subjects, to ovalbumin in two, to ovomucoid in one and to egg yolk in two subjects. They were also sensitized to wheat, rye and barley flours. Specific IgE determinations to egg white were positive in all patients, to lysozyme in two, to ovalbumin in three, to ovomucoid in two and to egg yolk in two of them. Methacholine inhalation tests revealed bronchial hyperresponsiveness in all workers (PC20 < 16 mg/ml). SICs were performed with aqueous extracts of lysozyme (n = 4), ovalbumin (n = 2) and ovomucoid (n = 1), which elicited isolated early asthmatic reactions in all subjects. Double-blind, placebo-controlled, oral challenge tests with raw egg white were positive in three subjects. CONCLUSIONS: These bakery workers had developed IgE-mediated occupational asthma to hen's egg white proteins.     

Molecular and immunological analysis of hen’s egg yolk allergens with a focus on YGP42 (Gal d 6)

Allergy to hen’s (Gallus domesticus) egg white is one of the most common forms of food allergy. Allergy to hen’s yolk also exists however, to a lesser extent when compared to egg white allergy. Two minor allergens from the hen’s egg yolk known as α-livetin (Gal d 5) and YGP42 (Gal d 6) were discovered recently. In this study, we investigated whether sensitization to egg white is associated with reactivity to egg yolk as well. Sera obtained from 25 patients with allergy to egg white were tested for specific IgE binding for egg yolk proteins through western immunoblotting. 36% of patients were found with true IgE-sensitization against egg yolk proteins. It was found that most of the IgE reactive yolk proteins were fragments of major precursor proteins of hen; vitellogenin-1 (VTG-1), vitellogenin-2 (VTG-2) and apolipoprotein B (Apo B). The egg yolk allergen Gal d 6 is the C-terminal part of VTG-1 and was found to be allergenic in significant percentage of egg white allergy patients. These results highlight the significance of Gal d 6 as an important allergen of egg yolk. Therefore, the secondary aim of this study involved developing a recombinant version of YGP42 in an Escherichia coli expression system. Recombinant Gal d 6 (rGal d6) was expressed as a fusion peptide with a 6 × His tag and purified using metal chelating resin. The inhibition ELISA results showed that rYGP42 was IgE reactive and was able to inhibit IgE binding to crude egg yolk (CEY) by up to 30%. Traditionally, it was thought that allergy to egg yolk occurred independently from sensitization to egg white. This study underlies the importance of concomitant sensitization to egg yolk proteins in patients allergic to egg white. Evidence reported in this study strongly suggests that egg yolk has potentially undiscovered allergens and therefore warrants further investigation. Furthermore, IgE reactive Gal d 6 presented in this study has the potential to be used in diagnosis and immunotherapy to treat egg allergy.     

Allergens in the white and yolk of hen's egg. A study of IgE binding by egg proteins

The radioallergosorbent test (RAST) was used to compare the IgE binding of egg white and yolk, and allergenic proteins were detected by immunoelectrotransfer ('Western blotting'). The main allergens were found in egg white, but for a large proportion of the egg-sensitive patients, yolk contained specific IgE-binding constituents. For blood sera from 36 patients, there was a positive correlation between the results of RAST for egg white and for yolk. Lysozyme was found to be an allergen for some patients. The effect of heating on the allergenicity of egg white was examined and the allergenicity of hen egg white was compared with that of a duck egg. The allergens in yolk were associated with each of the three yolk fractions, and several of the proteins in the low-density lipoprotein fraction bound IgE.     

Specific serum IgE in the diagnosis of egg and milk allergy in adults

Levels of specific serum IgE to cow's milk, whole hen's egg, egg white, and egg yolk were compared to the outcome of double-blind, placebo-controlled food challenge 'DBPCFC) with fresh egg and/or milk in 21 adults with a case history of immediate hypersensitivity to egg and/or milk. Specific serum IgE was measured by four different commercially available tests and by an inhouse Maxisorp RAST using freshly prepared food extracts. Sensitivities and negative predictive accuracies were generally high with egg white and milk, but low with egg yolk. Specificities and positive predictive accuracies were low for all allergens and tests. Changing the cutoff levels did not improve the ability of the tests to predict clinical allergy. Among commercially available test allergens, egg white gave the most consistent results in levels and class scores, and the highest degree of concordance with DBPCFC, whereas egg yolk and milk varied more. Applying freshly prepared food extracts in Maxisorp RAST did not improve diagnostic value. Measuring specific serum IgE levels in control subjects tolerant to egg/milk showed that false positive reactions occurred frequently among patients with another food allergy and atopic dermatitis, whereas most tests were likely to be negative in pollen-allergic and nonallergic volunteers. In conclusion, specific IgE measurements with egg white and milk were useful for exclusion of symptomatic hypersensitivity to egg and milk in patients with a positive history, whereas DBPCFC is still mandatory in patients with positive history and positive test. Measuring egg-yolk-specific IgE or using freshly prepared food extracts for specific IgE measurements added no further diagnostic information. The rate of clinically insignificant positive test results seems to be influenced by the prevalence of other food allergies and/or atopic dermatitis in the population under study.     

Specific T cell lines for ovalbumin, ovomucoid, lysozyme and two OA synthetic epitopes, generated from egg allergic patients' PBMC

Background Proteitis of hen egg white are common ingredients of food and difficult to eliminate. Allergens of egg while induce allergic symptoms among relatively high numbers of palients suffering from food allergy. B cell epitopes to hen egg white tnajor allergens have been reported. Considering that IgE antibody formation is mostly T cell dependent, the study of T cell epitopes is essential for both T cell dependent and independent IgE response. Objectives Little information on T cell epitopes recognizing food allergens has been reported. T cell responses to hen egg white allergens and two synthetic OA peptides located at amino acid residues No. 105–122 and 323–339 were investigated. Methods Peripheral blood mononuclear cells from hen egg allergic patients were investigated. Various allergens of hen egg white were used for stimulation. Primary proliferation responses were detected followed by the generation of long-term cultures which were examined for their specificity, phenotype, cytokine profile and IgE production. The allergen specific T cell lines were mapped using a panel of 13 synthetic peptides of ovalbumin. Results Human T cells recognizing ovomucoid, lysozyme and ovalbumin epitope 105–122 are reported for the first time. The cell lines were enriched CD4⁺/CD8⁺ T cells (CD2⁺ 95%). Ovomucoid and ovalbumin induced IgE synthesis by a small fraction of B cells (1%) present in the ovalbumin and ovomucoid specific T cell lines. Conclusions Human T cells recognized several egg white allergens and epitopes within the ovalbumin molecule. Specific IgE was produced in cultures stimulated with ovalbumin and ovomucoid. OA peptides 105–122 and 323–339 have no affinity to the specific IgE of the two patients; an observation which could be of particular interest regarding the mechanisms of peptide-based immunotherapy.     

Common allergens in avian meats.

BACKGROUND: Reports of allergy to bird meats are uncommon, and most have been in patients with "bird-egg syndrome." OBJECTIVE: We sought to evaluate 3 patients who reported allergic reactions to several avian meats, but who denied allergic reactions to eating eggs. The patients required yellow fever vaccine for entry into the military. METHODS: Patients were skin tested with commercial extracts of chicken, turkey, and egg, as well as with crude extracts made from dove and quail meat, and with yellow fever vaccine. Immunoblots for IgE antibody were performed by using the same materials used for skin testing plus extracts of duck and goose meat. RESULTS: Skin tests were positive in all 3 patients to chicken, turkey, dove, quail, and yellow fever vaccine and negative to egg. This included some positive skin test responses to bird meats the patients denied ever having eaten. The vaccine was administered in graded doses. Immunoblots revealed IgE binding to several proteins of similar molecular weights in all of the avian meats but not to egg or yellow fever vaccine. Again, this included IgE antibody to some bird meats the patients denied ever having eaten. CONCLUSION: Patients allergic to one bird meat may be allergic to others, including game birds, probably because of cross-reacting allergens. Such patients may have to exercise caution even when eating bird meats they have not previously ingested. The relationship of this allergy to yellow fever vaccine, if any, remains to be determined.     

New allergens from hen's egg white and egg yolk. In vitro study of ovomucin, apovitellenin I and VI, and phosvitin

Three hen egg yolk proteins, apovitellenins I and VI and phosvitin, and one egg white protein, ovomucin, were purified and tested for their ability to bind IgE in the sera of patients hypersensitive to egg. All of the proteins bound IgE from the sera of egg-allergic individuals in the radioallergosorbent test, and they also inhibited binding of IgE to the parent fractions-either egg yolk (apovitellenins I and VI and phosvitin) or egg white (ovomucin). It appears that apovitellenins I and VI are major allergens for some of the individuals tested. This is the first report of the in vitro allergenicity of these proteins.     

Specificity of IgE antibodies to sequential epitopes of hen's egg ovomucoid as a marker for persistence of egg allergy

BACKGROUND: Approximately two-thirds of egg-allergic infants become tolerant within the first 5 years of life. OBJECTIVE: We sought (1) to compare the recognition of sequential (linear) and conformational binding sites of ovomucoid, ovalbumin and ovotransferrin, by IgE antibodies of children with persistent and transient egg allergy, (2) to identify immunodominant IgE-and IgG-binding epitopes of ovomucoid, and (3) to compare epitope-specificity of IgE antibodies between patients with differing natural histories of egg allergy. METHODS: Using immunodot-blots or ImmunoCAPs, IgE-antibodies against conformational (native) and sequential (reduced and alkylated) egg proteins were determined at the time of clinical reactivity in patients who retained their allergy and in those who developed clinical tolerance. IgE- and IgG-binding epitopes were mapped for ovomucoid using overlapping decapeptides on SPOTs membranes. Recognition of the major IgE-binding epitopes were compared between patients with differing natural histories of egg allergy. RESULTS: The patients with long-lasting egg allergy had a higher concentrations of IgE antibodies against sequential and native ovomucoid and ovalbumin than the children who subsequently gained tolerance (P < 0.01). Four major IgE-binding epitopes were identified in ovomucoid at amino acid 1-10, 9-20, 47-56, and 113-124. IgE antibodies of all seven patients with persistent egg allergy recognized these epitopes whereas none of the 11 children who outgrew their egg allergy did so. CONCLUSIONS: Patients with persistent egg allergy develop IgE antibodies against more sequential and conformational epitopes of ovomucoid and ovalbumin. The presence of serum IgE antibodies to specific sequential epitopes of ovomucoid may be used as a screening instrument for persistent egg allergy.     

Special consideration is required for the component-resolved diagnosis of egg allergy in infants

BackgroundThere are few reports regarding differences in reactivity to the major egg allergens according to children's age, although component-resolved diagnosis is gradually being used.ObjectiveTo investigate differences in reactivity to major egg allergens among various age groups of children with egg allergy.MethodsTwenty-seven patients diagnosed with egg allergy were included. Egg allergy was defined as a convincing history of reproducible symptoms within 2 hours of egg consumption and an egg white–specific IgE level of at least 0.35 kU_A/L. Patients were divided into 3 age groups: younger than 12 months (group A, 7 subjects), 12 to 23 months (group B, 8 subjects), and at least 24 months (group C, 12 subjects). Immunoblotting and enzyme-linked immunosorbent assay investigated IgE reactivity toward ovalbumin, ovomucoid, and ovotransferrin in eggs.ResultsImmunoblotting analysis showed that all patients in group A reacted to ovalbumin, whereas reactions to other proteins were not detected. All patients in group B displayed a reaction to ovalbumin and ovomucoid. IgE binding to ovotransferrin was shown in 3 patients in group B. All patients in group C displayed reactivity to ovalbumin, 5 patients showed a reaction to ovomucoid, and 8 patients displayed a reaction to ovotransferrin. As a patient's age increased, specific IgE binding to ovalbumin and ovotransferrin increased (P = .011 and .004).ConclusionIgE reactivity to egg allergens differs according to children's ages.     

Modulation of egg white protein allergenicity under physical and chemical treatments

Hen eggs are one of the most common causes of food allergic reactions. Egg white, which is generally considered more allergenic than egg yolk, has four major allergenic proteins namely, ovomucoid, ovalbumin, ovotransferrin and lysozyme which are defined as immunodominant egg white proteins (EWP). The objectives of the present work were first to evaluate sensitivity to EWP of the population in the region of Fez-Meknes in Morocco, and then to study the effect of acid treatment and heating on the allergenicity of EWP. A cross-sectional study was carried out at the University Hospital in Fez and at analytical laboratories in Meknes in which 446 adults were recruited to establish a serum bank. Sera bank was used to evaluate specific IgE reactivity to EWP and the reactivity of this IgE to native and to heat- and acid-treated EWP. Immunoblots were also carried out to characterise the allergenic components. The results showed that 9.5% of the patients reported allergy to food. Among these patients, 4.2% reported allergy to eggs, 2.5% to peanuts and 0.4% to wheat flour. The study of the effect of temperature and acidity on the allergenicity of EWP showed that more than 50% of sera showed a decrease superior to 30% under heating or acid treatment. With a combination of these treatments, 75% of the sera showed a reduction of more than 30%. By means of immunoblot, we have shown that ovotransferrin and lysozyme are the major allergens for the population studied.     

Feature of food allergy developed during infancy (2)--acquisition of tolerance against hen's egg, cow's milk, wheat, and soybean up to 3 years old]

BACKGROUND: Once food elimination is introduced, it is important to know for doctors when patients generally develop oral tolerance against eliminated food. To clarify the point, following study was conducted. METHODS: We analyzed 304 patient profiles with food allergy in our division between 1994 and 2001. The diagnosis of oral tolerance was determined by the results of food challenges or the accidental episodes of ingestion. RESULTS: By the age of 3 years old, 78% of food allergy patients with soybean, 63% of those with wheat, 60% of those with cow's milk, 51% of those with egg yolk, and 31% of those with egg white developed oral tolerance, respectively. IgE CAP RAST scores against cow's milk, egg yolk, and egg white in the patients without tolerance were significantly higher than those in the patients with tolerance. CONCLUSION: Patients developed oral tolerance firstly against soybean followed by wheat, cow's milk, egg yolk and egg white during the first 3 years of life. The specific IgE antibody levels against egg and cow's milk are important for the diagnosis of tolerance.     

Cracking the egg: An insight into egg hypersensitivity

Hypersensitivity to the chicken egg is a widespread disorder mainly affecting 1–2% of children worldwide. It is the second most common food allergy in children, next to cow's milk allergy. Egg allergy is mainly caused by hypersensitivity to four allergens found in the egg white; ovomucoid, ovalbumin, ovotransferrin and lysozyme. However, some research suggests the involvement of allergens exclusively found in the egg yolk such as chicken serum albumin and YGP42, which may play a crucial role in the overall reaction. In egg allergic individuals, these allergens cause conditions such as itching, atopic dermatitis, bronchial asthma, vomiting, rhinitis, conjunctivitis, laryngeal oedema and chronic urticaria, and anaphylaxis. Currently there is no permanent cure for egg allergy. Upon positive diagnosis for egg allergy, strict dietary avoidance of eggs and products containing traces of eggs is the most effective way of avoiding future hypersensitivity reactions. However, it is difficult to fully avoid eggs since they are found in a range of processed food products. An understanding of the mechanisms of allergic reactions, egg allergens and their prevalence, egg allergy diagnosis and current treatment strategies are important for future studies. This review addresses these topics and discusses both egg white and egg yolk allergy as a whole.     

Egg protein sensitization in patients with bird feather allergy

We have studied the hypersensitivity lo hens egg protein and chicken meal in 25 adults with a previous diagnosis of bronchial asthma and rhinoconjunctivitis due to bird feather sensitization. Seventeen of the 25 reported good tolerance to the ingestion of egg and chicken meat. The skin tests were negative to both antigens in 15 of them, and positive for egg in two. All 17 patients had negative RAST to chicken meat and egg protein. The remaining eight patients had intolerance to egg, and three of them also to chicken meat ingestion; in seven of the eight eases allergic to egg, the alimentary intolerance began after the clinical symptoms of bird feather sensitization. In all eight cases the skin tests were positive to egg yolk, and in live of them also to egg white and chicken meal. These patients evidenced specific serum IgE antibodies to egg yolk, four of them to egg while, and seven to chicken meat. These results demonstrate (he high frequency (32%) of the association of sensitization lo egg proteins, particularly egg yolk, in a selected population of patients with known allergy to bird feathers, thus suggesting that in some patients feather sensitization could trigger or somehow facilitate the later sensitization to egg yolk proteins.     

Utility of diagnostic tests in the follow-up of egg-allergic children

Background Better knowledge of the accuracy of a skin prick test (SPT) and specific IgE (sIgE) levels to egg allergens would help to identify persistent egg‐allergic children, avoiding unnecessary risky challenges. This study was designed to assess the accuracy of a SPT and sIgE levels to egg allergens in order to determine persistent egg allergy in IgE‐mediated allergic children after an egg‐free diet. Methods Children below 16 years were prospectively and consecutively recruited. Inclusion criteria were: allergy to egg proteins (children with a positive clinical case of IgE‐mediated egg allergy and a positive SPT to egg allergens and/or positive sIgE levels), and strict egg avoidance diet followed for at least 6 months. Clinical histories were recorded and all patients underwent SPTs, sIgE levels to egg allergens and the gold standard ‐a double‐blind placebo‐controlled egg challenge (DBPCFG). DBPCFG was interpreted without knowledge of the results of the other tests and vice‐versa. A SPT and sIgE levels' ROC curves analysis was performed to compare the diagnostic performance of the different tests. Results Finally, 157 children were included in the study. One hundred out of these 157 children (63.7%) had a positive oral challenge. Ninety‐six were male (61%), and the median age was 2.5 years. One hundred and three (66.9%) had atopic dermatitis. A 7 mm egg white prick test had a positive likelihood ratio (+LR) of 6.7, and a level of 1.3 KU/L egg white‐sIgE had a +LR of 5.1. A 7 mm egg white SPT had a positive predictive value of 92.3% (95% CI 85.1–99.5), and for a 9 mm egg white SPT this value was 95.6% (95% CI 87.3–100.0). For egg white‐sIgE, 1.5 KU/L had a positive predictive value of 90.4% (95% CI 82.4–98.4) and for 25 KU/L it was 100.0% (95% CI 100.0–100.0). SPTs with ovotransferrin and lysozyme showed the lowest accuracy, followed by yolk and ovalbumin SPTs. Conclusion This study is the first to evaluate both tests (SPT and sIgE levels) and all egg allergens to determine the persistence of egg allergy in IgE‐mediated allergic children. Measuring the SPT and sIgE levels is useful to predict persistent allergy in these children, especially with the egg white complete extract. An oral challenge should not be performed in egg allergic paediatric patients with either an egg white prick test above 7 mm or a white egg‐sIgE determination above 1.3 KU/L, because there is a 90% probability of remaining allergic.     

Contact urticaria to giraffe hair

BACKGROUND: Immediate-type hypersensitivity to animal proteins is a common problem in people occupationally exposed to animals. METHODS: A 19-year-old female working as a voluntary zookeeper in her off-time suffered from hives on her forearms following contact to the fur of a giraffe. For diagnostic evaluation, skin prick tests, assessment of specific serum IgE antibodies, and basophil activation tests were performed. RESULTS: Skin prick tests with a standard series of common aeroallergens were positive for various pollens. Prick testing with native materials was positive for extracts of hair from two different giraffe subspecies in the patient, but not in control subjects. By CAP-FEIA, no specific serum IgE antibodies to dander of a large variety of animals were found in the patient. In the basophil activation test, expression of the activation marker CD63 was induced by extract of giraffe hair on the cells from the patient, but not on those from unaffected controls. CONCLUSIONS: This patient suffers from an 'exotic' immediate-type contact allergy to giraffe hair.     

Validity of specific IgE antibodies in children with egg allergy

BACKGROUND: The demonstration of specific IgE antibodies to egg supports the existence of allergy to this food, but a correct diagnosis can only be obtained after a challenge test. Several studies have assessed different cut-off points in the level of these antibodies as predictors of clinical reactivity. OBJECTIVE: Validation of the specific IgE antibodies measured by the CAP System Fluorescence enzyme immunoassay (FEIA) technique in the diagnosis of egg allergy in children under 2 years of age. METHODS: A prospective study of 81 children with suspected egg allergy was performed. Specific IgE antibodies was quantified for egg white, egg yolk, ovoalbumin and ovomucoid. The diagnostic challenge test was carried out following the previously established criteria. The validity of the specific IgE antibodies was analysed using children with a negative diagnostic challenge test as control group. RESULTS: The prevalence of egg allergy in the group studied was 79% and egg white was the allergen that showed the greatest diagnostic efficacy. The sensitivity and positive predictive value of the prick test and of the CAP to egg white were excellent and the specificity and the negative predictive value had lower values. A level of > or = 0.35 KU(A)/L for specific IgE antibodies to egg white predicted the existence of reaction in 94% of the cases. CONCLUSIONS: Quantification of the specific IgE antibodies to egg white is useful in the diagnosis of egg allergy. In children under 2 years of age with a background of immediate hypersensitivity after egg ingestion and presence of specific IgE antibodies to egg white of > or = 0.35 KU(A)/L, diagnostic challenge test is not necessary to establish the diagnosis of allergy to this food.     

Allergy to goat and sheep cheese with good tolerance to cow cheese

BACKGROUND: We report on a patient who experienced allergic reactions after eating goat cheese and after touching goat and sheep cheese, but not after consuming cow's milk dairy products. OBJECTIVE: To assess the allergenicity and IgE-binding capacity of the caseins from the three different species. METHODS: Skin prick tests were carried out using whole milk and caseins from three different species (goat, sheep and cow), and whey fractions of cow's milk. Total serum IgE and specific IgE to cow's milk proteins were measured by CAP system and specific IgE against caseins and whole milk were determined by ELISA technique. To evaluate allergenic cross-reactivity, inhibition of the IgE ELISA activity to goat's milk and goat casein was tested for the three caseins. SDS-PAGE and immunoblotting was used to determine IgE binding bands in caseins. RESULTS: Skin tests were positive to sheep and goat's milk, sheep and goat casein, as well as to sheep and goat cheese. Total serum IgE was 66 kU/L and IgE determinations by CAP were negative. IgE ELISA against the caseins from goat and sheep was strongly positive, whereas it was negative to cow casein. ELISA inhibition assays revealed a high degree of cross-reactivity between goat casein and sheep casein. Immunoblotting showed three IgE-binding bands in goat casein at 31, 27 and 22 kDa, which may correspond to alpha-, beta- and gamma-caseins. A band at about 31 kDa was observed in sheep casein and another band at 34 kDa was recognized in cow casein. CONCLUSION: This patient developed allergy to goat and sheep cheese with good tolerance to cow's milk. We identified goat casein as the main allergen causing sensitization in this patient as demonstrated by in vivo and in vitro tests. A high degree of cross-reactivity between goat and sheep casein was observed.     

Antibodies against hen's egg proteins in pigeon breeder's disease

The serum of patients with pigeon breeder's lung (PBL) contains IgG-class antibodies against pigeon serum proteins. These antibodies cross-react strongly with the sera of other avian species. Cross-reactivity, as demonstrated by precipitation, complement fixation, haemagglutination and microELISA, is also exhibited with the water-soluble proteins in hen's egg yolk and egg white. The phenomenon appears to be due to the presence of hen serum proteins in the eggs, which occur particularly concentrated among the water-soluble proteins in the yolk (‘livetins’). It is proposed that anti-egg antibodies may explain the frequent serological finding of‘false-positive’asymptomatic pigeon breeders.     

Chicken serum albumin (Gal d 5*) is a partially heat-labile inhalant and food allergen implicated in the bird-egg syndrome

BACKGROUND: Chicken serum albumin (alpha-livetin) has been implicated as the causative allergen of the bird-egg syndrome. However, the clinical relevance of sensitization to this allergen has not been confirmed by specific challenge tests and environmental sampling. We investigated whether chicken albumin can be detected in air samples collected in a home with birds, and whether sensitization to this protein may cause respiratory and food allergy symptoms. The heat resistance of chicken albumin and the possible cross-reactivity with conalbumin were also investigated. METHODS: We studied eight patients with food allergy to egg yolk who also suffered from respiratory symptoms (rhinitis and/or asthma) caused by exposure to birds. Sensitization to egg yolk and bird antigens was investigated by skin and serologic tests. Hypersensitivity to chicken albumin was confirmed by specific bronchial, conjunctival, and oral provocation tests. RESULTS: All patients had positive skin tests and serum IgE against egg yolk, chicken serum, chicken meat, bird feathers, and chicken albumin. The presence of airborne chicken albumin in the domestic environment was confirmed. Specific bronchial challenge to chicken albumin elicited early asthmatic responses in six patients with asthma. An oral challenge with chicken albumin provoked digestive and systemic allergic symptoms in the two patients challenged. IgE reactivity to chicken albumin was reduced by 88% after heating at 90 degrees C for 30 min. ELISA inhibition demonstrated only partial cross-reactivity between chicken albumin and conalbumin. CONCLUSION: Chicken albumin (Gal d 5) is a partially heat-labile allergen that may cause both respiratory and food-allergy symptoms in patients with the bird-egg syndrome.