Cross-reactive and species-specific immunoglobulin E epitopes of plant profilins: an experimental and structure-based analysis

BACKGROUND: Profilins are cross-reactive plant allergens responsible for multiple pollen sensitization and pollen-associated food allergy. While it is assumed that profilins from different species are immunologically equivalent, some studies suggest partial or even lacking IgE cross-reactivity between certain profilins. OBJECTIVE: We aimed to obtain a semi-quantitative assessment of the contributions of conserved and species-specific epitopes to IgE binding of plant profilins. METHODS: We compared model structures of profilins from timothy, mugwort, celery and bell pepper with crystal structures of birch and latex profilins. We predicted potential conformational epitopes that consisted of contiguous patches of at least 20% surface-exposed residues. Celery and timothy profilins were purified from their natural sources, and profilins from birch, mugwort, bell pepper and latex were expressed in Escherichia coli. The structural integrity of all purified proteins was confirmed by circular dichroism spectroscopy. IgE ELISAs and ELISA inhibitions using sera from 22 profilin-sensitized allergic patients were carried out. RESULTS: Peptide backbone conformations of all six profilins were highly similar. Nine variable epitopes and two containing high proportions of conserved residues were predicted. IgE from all sera bound to all tested profilins and the amounts were highly correlated. However, IgE inhibition experiments revealed that up to 60% of total IgE binding was mediated by species-specific epitopes. The extent of cross-reactivity among profilins from timothy, birch, latex and celery was greater than cross-reactivity to mugwort and bell pepper profilins. This pattern was mirrored by sequence similarities among one of the predicted variable epitopes. Patients with IgE to cross-reactive epitopes displayed allergic reactions to a greater number of plant foods than patients having IgE directed to species-specific epitopes. CONCLUSION: The large extent of cross-reactivity among plant profilins justifies using a single profilin for diagnosis. However, the fine specificity of IgE directed to variable epitopes may influence the clinical manifestation of profilin sensitization.     

IgE cross-reactivity between birch pollen, mugwort pollen and celery is due to at least three distinct cross-reacting allergens: immunoblot investigation of the birch-mugwort-celery syndrome

Background Allergy to celery is often associated with sensitization to birch and/or mugwort pollen. Objective and methods In a multi-centre study, sera from 23 patients suffering from type I allergy to celery and 15 patients with positive celery RAST but wo clinical sensitization were compared. To examine whether cross-reactivity between celery and mugwort pollen iticludes cross-sensitization to birch pollen allergens, we determined cross-reacting structures in birch pollen, mugwort pollen and celery by means of immunoblotting. Inhibition studies were performed by preincubation of sera with extracts of birch pollen, mugwort pollen, and celery. Results We identified three groups of proteins—homologues of Bet v I and birch profilin (Bet v 2) as well asa group of proteins with a molecular range of 46 to 60 kD—displaying IgE-cross-reactivity, which were shared by birch pollen and celery. Two of these groups of allergens (profilin and the 46 to 60 kD proteins) were also present in mugwort pollen. In this paper we demonstrate that most cross-reacting allergens present in mugwort pollen and celery can also be detected in birch pollen extract. Conclusion Therefore we propose, from a serological point of view, to extend the mugwort-celery syndrome to the birch-mugwort-celery syndrome.     

A study of allergens in celery with cross-sensitivity to mugwort and birch pollens

Sixty-one sera with positive RAST to mugwort pollen ( Artemisiae vulgaris ) were submitted to RASTs for birch pollen ( Betula verrucosa) and celery ( Apium graveolens ). In 36 cases RAST results were positive for celery. In addition, 23 sera presented specific IgE to birch pollen. The binding of specific IgE to individual allergens in celery, mugwort pollen and birch pollen was studied by the immunoblotting technique. This involved electrophoretic separation of allergenic extracts, electrotransfer of proteins onto nitrocellulose sheets and sensitive immunoenzymatic detection. Eighteen sera had specific IgE binding to two celery components of molecular weight around 15 kD. All these sera also detected a 15 kD allergen in mugwort and two allergens in birch of 14 kD and 16 kD molecular weight. The sera that did not detect the 15 kD bands in celery failed to react with both the 15 kD mugwort component and the 14 and 16 kD birch components. Specific cross-inhibitions of the detection of these allergens on immunoblots were obtained by pre-incubation of the sera with crude extract of the three species. These results strongly suggest that such allergens display some structural identity and that they could be at the origin of some cases of crossed hypersensitivity to celery, mugwort pollen and birch pollen.     

Allergens in pepper and paprika

Mugwort and birch pollen allergy are frequently associated with IgEmediated hypersensitivity to celery and spices. We analyzed 22 sera from patients with the mugwort-birch-celery-spice syndrome for IgE binding to the spices pepper and paprika by immunoblotting. Immunoblot results revealed two major allergens of 28 and 60 kDa in pepper and a 23-kDa allergen together with allergens of higher molecular weight in paprika. In immunoblot-inhibition studies, crude mugwort, birch pollen, and celery extracts significantly reduced the IgE binding to pepper and paprika allergens. However, no inhibition was achieved with rBet v 1 and rBet v 2, suggesting that no homologs of these birch proteins act as allergens in pepper or paprika extracts, N-terminal sequence analysis of the 14- and 28-kDa pepper and 23-kDa paprika allergens revealed no homology to known allergens. The 28-kDa pepper allergen showed homology to a wheat germin protein, and the 23-kDa paprika allergen was identified as a homolog of a osmotin-like or pathogenesis-related protein in tomato. Therefore, we conclude that the IgE cross-reactivity in the mugwort-birch-celery-spice syndrome to the spices pepper and paprika is not caused by homologs of Bet v 1 and profilin, N-terminal amino acid sequence analysis of the main allergens in pepper and paprika indicate a relation to frequently occurring plant proteins.     

Allergenic cross-reactivity of olive pollen

BACKGROUND: Sera of patients allergic to olive (Olea europaea) pollen were used to analyze the IgE cross-reactivity between olive-pollen extract and other pollens obtained from phylogenetically unrelated species. METHODS: We used IgE immunostaining of pollen extracts blotted to nitrocellulose membranes after SDS-PAGE and inhibition analysis of this binding. RESULTS: A high inhibition of the IgE binding on olive-pollen extract was exhibited by birch, mugwort, pine, and cypress pollens, suggesting that these extracts contain proteins which share common epitopes and thus can be recognized by olive-allergic sera. IgE binding to Gramineae pollen extracts was not inhibited by olive-pollen extract, indicating a primary sensitization of the patients to these species. From the inhibition assays, the presence of an allergen of 45 kDa in the olive pollen, which has no homologous counterparts in other allergenic species, has been inferred. CONCLUSIONS: Olive pollen contains allergens which cross-react with pollens from unrelated species, a fact that could simplify the diagnosis and treatment of pollinosis.     

Type I allergy to elderberry (Sambucus nigra) is elicited by a 33.2 kDa allergen with significant homology to ribosomal inactivating proteins

BACKGROUND: Patients suffering from allergic rhinoconjunctivitis and dyspnoea during summer may exhibit these symptoms after contact with flowers or dietary products of the elderberry tree Sambucus nigra. OBJECTIVE: Patients with a history of summer hayfever were tested in a routine setting for sensitization to elderberry. Nine patients having allergic symptoms due to elderberry and specific sensitization were investigated in detail. We studied the responsible allergens in extracts from elderberry pollen, flowers and berries, and investigated cross-reactivity with allergens from birch, grass and mugwort. METHODS: Sera from patients were tested for IgE reactivity to elderberry proteins by one-dimensional (1D) and 2D electrophoresis/immunoblotting. Inhibition studies with defined allergens and elderberry-specific antibodies were used to evaluate cross-reactivity. The main elderberry allergen was purified by gel filtration and reversed-phase HPLC, and subjected to mass spectrometry. The in-gel-digested allergen was analysed by the MS/MS sequence analysis and peptide mapping. The N-terminal sequence of the predominant allergen was analysed. RESULTS: 0.6% of 3668 randomly tested patients showed positive skin prick test and/or RAST to elderberry. IgE in patients' sera detected a predominant allergen of 33.2 kDa in extracts from elderberry pollen, flowers and berries, with an isoelectric point at pH 7.0. Pre-incubation of sera with extracts from birch, mugwort or grass pollen rendered insignificant or no inhibition of IgE binding to blotted elderberry proteins. Specific mouse antisera reacted exclusively with proteins from elderberry. N-terminal sequence analysis, as well as MS/MS spectrometry of the purified elderberry allergen, indicated homology with ribosomal inactivating proteins (RIPs). CONCLUSION: We present evidence that the elderberry plant S. nigra harbours allergenic potency. Independent methodologies argue for a significant homology of the predominant 33.2 kDa elderberry allergen with homology to RIPs. We conclude that this protein is a candidate for a major elderberry allergen with designation Sam n 1.     

Occupational Allergy to Flowers: Immunoblot Analysis of Allergens in Freesia,Gerbera and Chrysanthemum Pollen

High exposure to pollen from ornamental flowers can induce an IgE‐mediated occupational allergy in florists and horticulture workers. We investigated IgE‐binding antigens in chrysanthemum, freesia and gerbera pollen by immunoblot analysis and analysed the cross‐reactivity of these pollen with birch, grass and mugwort pollen. In immunoblots with chrysanthemum pollen, major IgE‐binding structures were seen with a molecular weight (MW) of approximately 25, 45 and 65 kD. In the immunoblots with freesia pollen, IgE from freesia pollen was directed against two proteins with an MW of approximately 15 kD. Most sera showed IgE binding to an approximately 15 kD band in gerbera pollen; with some sera additional bands were seen in the range of 30–50 kD. IgE binding to chrysanthemum pollen was inhibited by mugwort pollen only, whereas IgE binding to freesia pollen was suppressed by birch, grass and mugwort pollen. The inhibitory activity of birch and grass pollen extract on IgE binding to gerbera pollen extract was serum dependent and ranged from no inhibition to complete inhibition. Occupational exposure to many different flowers induced IgE against all three types of pollen. Exposure in greenhouses to gerbera flowers elicited mainly IgE against gerbera pollen. Mugwort pollen extract inhibited IgE binding to pollen from all three flowers.     

Comparison of IgE and IgG antibody responses of atopic individuals with sensitization to tree and grass pollens

Sera of atopic individuals with predominant sensitization to either tree pollen (TAs) or tree and grass pollens (TGAs) as well as of nonatopic subjects (NAs) were analyzed for IgE, IgG, and IgG4 antibodies specific for grass pollen allergens. Of 600 atopic individuals with serum IgE antibodies specific for birch pollen allergens, 54% also had serum IgE antibodies specific for grass pollen. The mean titers of IgG antibodies specific for grass pollen proteins were about 10 times higher in the sera of TGAs than those in the TAs and NAs. SDS-PAGE immunoblotting analysis of grass pollen proteins using sera of TGAs, TAs, and NAs with respect to the binding of these proteins with IgE and IgG antibodies in these sera exhibited a similar pattern of variation. Quantitation by enzyme immunoassay of the antibody binding to a recombinant grass pollen allergen, rKBG8.3, further demonstrated that elevated IgG antibody levels in TGAs are mainly due to a broader range of specificities, and not to high specific binding to the individual protein. Statistically significant correlation was found between IgE and IgG4 antibodies specific for the Kentucky bluegrass (KBG) extract, but not for the isolated recombinant allergen. These results indicate that the grass pollens elicit a complex array of antibody specificities in both atopics and nonatopics, and that the profile of antibodies specific to the pollen extract and pure allergens differs, suggesting that single grass allergens may be inadequate for replacing grass pollen extracts for immunotherapy.     

Severe oral allergy syndrome and anaphylactic reactions caused by a Bet v 1- related PR-10 protein in soybean,SAM22

BACKGROUND: Anaphylactic reactions to soy products have been attributed to stable class 1 food allergens. OBJECTIVE: IgE- mediated reactions to a soy-containing dietary food product in patients allergic to birch pollen were investigated. METHODS: Detailed case histories were taken from 20 patients. Their sera were analyzed for IgE (UniCAP) specific for birch, grass, mugwort, the recombinant birch allergens rBet v 1 and rBet v2, and soy protein. Extracts from birch pollen, soy isolate, rBet v 1, and the recombinant PR-10 soy protein rSAM22 were coupled to paper disks or nitrocellulose for IgE measurements (enzyme allergosorbent test) or Western blot analysis. Enzyme allergosorbent testing, Western blot inhibition, and histamine release studies were performed with the same allergens. RESULTS: Most patients (17/20) experienced facial, oropharyngeal, and/or systemic allergic symptoms within 20 minutes after ingesting the soy product for the first time. Birch pollen allergy (16/20) was common, along with oral allergy syndrome to apple (12/20) or hazelnut (11/20). IgE levels to birch and Bet v 1 but not to other inhalants were high in 18 of 20 patients. Significant IgE binding to rSAM22 occurred in 17 of 20 patients. Blot experiments with the soy isolate revealed IgE-binding bands at 17 kd (15/20), 22 kd (1/20), and 35 to 38 kd (2/20); the former was inhibited by preincubation of the sera with rBet v 1 or rSAM22. Birch extract and soy isolate, rBet v 1, and rSAM22 induced dose-dependent histamine release in the nanomolar range. CONCLUSION: Immediate-type allergic symptoms in patients with birch pollen allergy after ingestion of soy protein-containing food items can result from cross-reactivity of Bet v 1 -specific IgE to homologous pathogenesis-related proteins, particularly the PR-10 protein SAM22.     

The allergen profile of ash (Fraxinus excelsior) pollen: cross-reactivity with allergens from various plant species

BACKGROUND: Ash, a wind-pollinated tree belonging to the family Oleaceae, is distributed world-wide and has been suggested as a potent allergen source in spring time. OBJECTIVE: The aim of this study was to determine the profile of allergen components in ash pollen in order to refine diagnosis and therapy for patients with sensitivity to ash pollen METHODS: The IgE reactivity profile of 40 ash pollen-allergic patients was determined by immunoblotting. Antibodies raised to purified pollen allergens from tree and grass pollens were used to identify cross-reactive structures in ash pollen extract. IgE immunoblot inhibition studies were performed with recombinant and natural pollen allergens to characterize ash pollen allergens and to determine the degree of cross-reactivity between pollen allergens from ash, olive, birch, grasses and weeds. RESULTS: The allergen profile of ash pollen comprises Fra e 1, a major allergen related to the major olive allergen, Ole e 1, and to group 11 grass pollen allergens, the panallergen profilin, a two EF-hand calcium-binding protein, a pectinesterase-like molecule and an allergen sharing epitopes with group 4 grass pollen allergens. Thus, the relevant allergens of ash are primarily allergens that share epitopes with pollen allergens from other tree, grass and weed species. CONCLUSIONS: Allergic symptoms to ash pollen can be the consequence of sensitization to cross-reactive allergens from other sources. The fact that ash pollen-allergic patients can be discriminated on the basis of their specific IgE reactivity profile to highly or moderately cross-reactive allergens has implications for the selection of appropriate forms of treatment.     

The major allergen of olive pollen Ole e 1 is a diagnostic marker for sensitization to Oleaceae

BACKGROUND: Trees of the family Oleaceae are important allergen sources, with a strongly varying geographic distribution. For example, olive pollen is an important allergen source in Mediterranean countries, whereas ash pollen dominates in Northern and Central Europe and North America. The aim of this study was to compare the profiles of olive and ash pollen allergens and to study the degree of cross-reactivity using populations of allergic patients selectively exposed to olive or ash pollen. METHODS: Olive and ash pollen extracts were analyzed by IgE immunoblotting using sera from Spanish patients highly exposed to olive pollen and Austrian patients without olive but ash pollen exposure. IgE cross-reactivity was studied by qualitative immunoblot inhibition assays and semiquantitative ELISA inhibitions using olive, ash, birch, mugwort, timothy grass pollen extracts and the major olive pollen allergen, Ole e 1. RESULTS: Spanish and Austrian patients exhibited an almost identical IgE-binding profile to olive and ash pollen allergens, with major reactivity directed against Ole e 1, and its homologous ash counterpart, Fra e 1. IgE inhibition experiments demonstrated extensive cross-reactivity between olive and ash pollen allergens. However, whereas cross-reactions between profilins and calcium-binding allergens also occurred between unrelated plant species, cross-reactivity to Ole e 1 was confined to plants belonging to the Oleaceae. CONCLUSIONS: Ole e 1 is a marker allergen for the diagnosis of olive and ash pollen allergy.     

Hypersensitivity to mugwort (Artemisia vulgaris) in patients with peach allergy is due to a common lipid transfer protein allergen and is often without clinical expression

BACKGROUND: The observation of mugwort-specific IgE antibodies in patients with peach allergy suggests that mugwort sensitization might play a role in sensitization to peach. OBJECTIVE: We sought to study the clinical manifestations of mugwort hypersensitivity in patients with peach allergy, identify the common allergens, and evaluate their IgE crossreactivity. METHODS: Patients with oral allergy syndrome for peach and specific IgE antibodies to mugwort were investigated for respiratory symptoms during the mugwort season. Peach and mugwort allergens were identified by means of SDS-PAGE and IgE immunoblotting. Immunoblotting inhibition experiments were done to study cross-reactivity between peach and mugwort and other pollens. RESULTS: Seventeen patients were studied, 10 with no seasonal respiratory symptoms and 7 with clear late summer respiratory symptoms. In IgE immunoblotting the 10 asymptomatic patients reacted only to a 9-kd allergen of both mugwort and peach, whereas the 7 patients with pollinosis reacted to other allergens. Ten patients with mugwort allergy, no history of allergy to peach, and negative results for peach-specific IgE antibodies were also studied. The mugwort 9-kd protein was identified as a lipid transfer protein (LTP) homologous to peach LTP. Immunoblotting inhibition showed that IgE binding to the peach 9-kd band was totally inhibited by 4 microg of peach LTP but only by 400 microg of mugwort LTP, whereas 4 microg of both mugwort and peach LTP totally inhibited the mugwort immunoblotting. The results were similar with other pollens. CONCLUSIONS: Patients sensitized only to the 9-kd LTP of mugwort do not present hay fever symptoms, and this sensitization is a consequence of the peach sensitization.     

Different IgE reactivity profiles in birch pollen-sensitive patients from six European populations revealed by recombinant allergens: an imprint of local sensitization

BACKGROUND: Sensitivity to birch pollen allergens is a common feature among European patients with seasonal pollen allergy. In this in vitro study, we examined the specific serum IgE binding profiles to individual birch pollen allergens in birch-sensitive patients from six European populations. METHODS: The study included 242 patients from Finland, Sweden, Austria, France, Switzerland and Italy. All suffered from seasonal rhinoconjunctivitis and/or asthma. Their sera were analyzed for specific IgE reactivity to individual birch pollen allergens (recombinant Bet v 1, Bet v 2 and Bet v 4) and natural birch pollen extract using Pharmacia CAP System and immunoblotting. RESULTS: Almost all Finnish, Swedish and Austrian sera contained IgE specific for Bet v 1 (>or=98%). Bet v 1-specific IgE antibodies were found in 90% of the French sera, and in 65 and 62% of the sera from Switzerland and Italy, respectively. Few Finnish (2%) and Swedish (12%) patients had IgE to Bet v 2, while Bet v 2 reactivity was more common in the other populations (20-43%). Reactivity to Bet v 4 was rare in all populations (5-11%) except for the Italian patients, in whom 3 of 11 sera were positive (27%). The immunoblot results supported the specific IgE profiles obtained with Pharmacia CAP System showing a broader IgE reactivity profile in patients from central and southern Europe as compared to northern Europe. CONCLUSION: Component-resolved allergy diagnosis with recombinant allergens reveals that the IgE reactivity profiles to individual birch pollen allergens vary between European populations. This observation may be explained by sensitization to different allergen sources and will have an impact on allergen-specific prevention and therapy strategies.     

The clinical relevance of sensitization to pollen-related fruits and vegetables in unselected pollen-sensitized adults

BACKGROUND: Previous studies have described cross-reactivity between fresh fruits, vegetables and pollen. However, no data demonstrates the clinical relevance of sensitization to pollen-related fruits and vegetables in unselected pollen-sensitized adults with and without symptoms in the pollen season. OBJECTIVE: The aim of this study was to estimate the clinical relevance of sensitization to pollen-related fruits and vegetables in unselected pollen-sensitized adults and to examine the diagnostic value of skin-prick test (SPT), histamine release and specific IgE compared with the outcome of oral challenge. METHODS: In total, 936 unselected adults (female : male 479 : 457, median age 33.7 years) were examined for pollen sensitization and clinical cross-reactivity with pollen-related fruits and vegetables by questionnaire, SPT, histamine release, specific IgE and oral challenge. RESULTS: The prevalence of pollen sensitization was 23.8% (n = 223). The probability of a clinical reaction to pollen-related foods in the respective pollen-sensitized groups was: 24% (birch), 4% (grass), 10% (mugwort), 35% (birch + grass), 8% (grass + mugwort) and 52% (birch + grass + mugwort). The odds ratio of a clinical reaction to pollen-related fruits and vegetables in symptomatic pollen-sensitized adults was as high as four times (birch + grass) the odds ratio of a clinical reaction in asymptomatic pollen-sensitized adults. CONCLUSION: This study not only demonstrates a high prevalence of clinical reactions to fruits and vegetables in pollen-sensitized adults, but also a discrepancy between the prevalence of sensitization to fruits and vegetables and the clinical relevance in different pollen-sensitized groups with symptoms in the pollen season as a significant factor.     

IgE crossreactivity between mugwort pollen (Artemisia vulgaris) and hazelnut (Abellana nux) in sera from patients with sensitivity to both extracts

Background An association between sensitization to Compositae pollens and hypersensitivity to hazelnut has been previously described. There is no previous in vitro study about crossreactivity between mugwort pollen and hazelnut. Objectives To study mugwort pollen and hazelnut allergens and to assess if there is IgE crossreactivity between mugwort pollen and hazelnut. Methods A serum pool formed by 28 individual sera with specific IgE to mugwort pollen and hazelnut was used to investigate IgE crossreactivity. RAST-inhibition, SDS-PAGE/IEF immunoblotting inhibition assays were performed by preineubation of the sera with mugwort pollen and hazelnut. Results RAST to hazelnut was inhibited up to 63% by mugwort pollen, but the mugwort pollen RAST was only inhibited up to 36% by hazelnut. In SDS-PAGE immunoblotting mugwort pollen showed nine allergens ranging from < 16 to 65kDa and hazelnut had four main allergens: 42kDa, 17kDa and < 16kDa (two bands). In the SDS-PAGE immunoblotting inhibition hazelnut partially inhibited all the mugwort pollen bands, except that with 19kDa, whereas mugwort pollen produced a nearly total inhibition of all the hazelnut allergens. In isoeleetrofocusing immunoblotting mugwort pollen had two groups of allergens: pI 7.5–8.5 and pi 3.5–5.2 and hazelnut one group of allergens: pI 5.2–5.8. In the isoeleetrofocusing immunoblotting inhibition hazelnut produced a partial inhibition of all the bands of mugwort pollen and mugwort pollen partially inhibited all the allergenic bands of hazelnut. Conclusions The RAST and SDS-PAGE/IEF immunoblotting inhibition results provide evidence of IgE cross reactivity between mugwort pollen and hazelnut allergens. The inhibition of hazelnut by mugwort pollen is higher than the inhibition of mugwort pollen by hazelnut in both RAST inhibition and SDS-PAGE immunoblotting inhibition. These results suggest that mugwort pollen allergens would behave as primary immunogens in the association between sensitivity to mugwort pollen and hazelnut.     

Sensitization to different pollens and allergic disease in 4-year-old Swedish children

BACKGROUND: Although the relationship between sensitization to different inhalant allergens in adolescents and adults has been intensively studied, information concerning sensitization in children is scarce in particular to pollens. OBJECTIVES: In 4-year-old children to elucidate the pollen immunoglobulin (IgE) antibody profile (birch only, timothy only and combinations of three pollens (birch, timothy or mugwort) and to relate the results to other inhalant and food allergens, as well as the presence of allergic diseases. METHODS: A total of 2551 4-year-old children belonging to a prospective birth cohort, which has been followed longitudinally (BAMSE), were investigated with respect to IgE antibodies to pollen and other inhalant and food allergens, and expression of allergic disease, based on questionnaire data. RESULTS: Eleven percent (n=285) of the children were sensitized to pollen. Birch was the dominating cause of pollen sensitization (birch sensitization only, n=133); followed by timothy grass pollen (n=56) and a combination of two (n=64) or three (n=30) pollens. A remarkably high proportion of the children sensitized only to birch was also sensitized to other inhalant allergens. This was not seen for children sensitized only to timothy. The highest frequencies of IgE reactivity to food were found in the group of children sensitized to the combination of birch, timothy and mugwort pollen. Children sensitized to timothy only, exhibited symptoms of allergic disease significantly less frequently compared with children sensitized to birch only. Sensitization to birch pollen was found to be closely associated with rhinitis and eczema compared with asthma. The highest frequency of asthma and/or rhinitis and/or eczema was reported in children sensitized to at least two pollens. CONCLUSION: Our results demonstrate that birch is the dominating source of pollen sensitization at the age of four in Sweden. This might associate with the pattern of sensitization to other inhalant and food allergens as well as influence on the expression of allergic disease in this particular age group.     

Primary versus secondary immunoglobulin E sensitization to soy and wheat in the Multi-Centre Allergy Study cohort

Background IgE sensitization to soy and wheat is classified as ‘primary’ when generated by food ingestion and ‘secondary’ when it as a consequence of primary sensitization to cross‐reacting pollen antigens via inhalation. The age‐specific relevance of these categories of sensitization throughout childhood is unknown. Objective To monitor the natural course of IgE sensitization against common food allergens in childhood in relation to sensitization against cross‐reactive airborne allergens. Methods The German Multi‐Centre Allergy Study with follow‐up from birth to age 13 recruited initially 1314 children. IgE antibody levels against cow's milk, hen's egg, soy, wheat, mites, cat and dog dander, birch and grass pollens were tested. Longitudinal data were analysed from the 273 children with sera obtained at age 2, 5, 7 and 10 years of age. Results The point prevalence of sensitization (>1.0 kU/L) to milk and egg allergens progressively decreased from about 4% at 2 years to <1% at 10 years. By contrast, the prevalence of IgE to wheat and soy progressively increased with age, from 2% to 7% (soy) and from 2% to 9% (wheat). At 10 years of age, IgE to grass pollen was detected in 97% and 98% of the children reacting against soy and wheat, respectively; IgE to birch pollen was observed in 86% and 82% of the children reacting against soy and wheat, respectively. Early IgE sensitization to soy or wheat preceded that to grass or birch pollen in only 4% and 8% of participants sensitized to soy and wheat, respectively. Conclusion IgE sensitization to soy and wheat is relatively uncommon and mostly primary in early infancy, more frequent and mostly secondary to pollen sensitization at school age. Clinical Implications Awareness should be raised to avoid unnecessary diet restrictions due to the high frequency of clinically irrelevant, secondary sensitization to soy and wheat in schoolchildren with pollinosis.     

Anaphylaxis to camomile: clinical features and allergen cross-reactivity

BACKGROUND: Medicinal remedies of plant origin became very popular in recent years, and allergic reactions to these are on the rise, accordingly. Camomile has been reported as a potential trigger of severe anaphylaxis. The allergens responsible for camomile allergy have not been characterized as yet. OBJECTIVE: The present study aims at reviewing the clinical symptomatology of immediate-type reactions in a series of patients sensitized to camomile and at characterizing the responsible allergens. METHODS: Fourteen patients with a history of allergy either to camomile or to spices or weeds, and a positive skin prick test/RAST to camomile were investigated for related allergic reactions to food, pollen and others. IgE-binding patterns were determined by immunoblotting, inhibition tests and deglycosylation experiments. RESULTS: Ten of 14 patients had a clinical history of immediate-type reactions to camomile, in some cases life threatening. Eleven subjects were also sensitized to mugwort in prick or RAST, eight to birch tree pollen. Using a polyclonal rabbit anti-Bet v 1 antibody, a homologue of the major birch pollen allergen Bet v 1 was detected in two camomile blots. In four cases a group of higher molecular weight allergens (23-50 kDa) showed IgE-binding to camomile. All allergens proved heat stable. Binding was inhibited in variable degrees by extracts from celery roots, anize seeds and pollen from mugwort, birch and timothy grass. Deglycosylation experiments proved the presence of carbohydrate determinants in camomile which were not responsible for IgE-binding, though. Profilins (Bet v 2) were not detected in our camomile extracts. CONCLUSION: Incidence and risk of type I allergy to camomile may be underestimated. Concurrent sensitization to mugwort and birch pollen is not infrequent. Bet v 1 and noncarbohydrate higher molecular weight proteins were found to be eliciting allergens and are responsible for cross-reactivity with other foods and pollen.     

Sensitization to grass, ragweed, mugwort pollen allergens in Japanese monkeys (Macaca fuscata): preliminary report

BACKGROUND: The natural occurrence of Japanese cedar (CJ, Cryptomeria japonica) pollinosis has been reported in Japanese monkeys (Macaca fuscata). Furthermore, most of these monkeys with CJ pollinosis have immunoglobulin (Ig) E sensitization to Japanese cypress (Chamaecyparis obtusa) pollen. However, specific IgE to other pollens has not yet been reported. OBJECTIVES: The present study was designed to investigate IgE sensitization of Japanese monkeys to grass, ragweed, and mugwort pollen. METHODS: Serum samples from 47 monkeys as a general population in one troop were collected at random. We measured specific IgE to grass, ragweed and mugwort pollen. Next, 10 monkeys with CJ pollinosis from the same troop were also examined for their IgE sensitization to grass, ragweed, and mugwort pollen. RESULTS: Of 47 monkeys, 13 (28%) had specific IgE to CJ pollen, 15 (32%) to grass pollen, five (11%) to ragweed pollen, and three (6%) to mugwort pollen. Furthermore, CJ pollinosis monkeys seemed to be sensitized to these pollen allergens with higher frequency; of 10 monkeys, 10 (100%) had specific IgE to CJ pollen, six (60%) to grass pollen, four (40%) to ragweed pollen, and two (20%) to mugwort pollen. CONCLUSION: Japanese monkeys had specific IgE to grass, ragweed, and mugwort pollen in addition to CJ pollen.