Co-sensitization to the three non-homologous major cashew allergens Ana o 1, Ana o 2 and Ana o 3 is caused by IgE cross-reactivity.

BACKGROUND: Cashew nuts often cause strong allergic reactions, even exceeding those of peanuts. Ana o 1 (vicilin), Ana o 2 (legumin) and Ana o 3 (2S albumin) are major cashew allergens. Co-sensitization to all three non-homologous cashew nut allergens has been observed. We hypothesize that this might be due to IgE cross-reactivity. METHODS: IgE cross-inhibitions were performed with Ana o 1-3 using sera from cashew nut allergic patients. Related hazelnut allergens Cor a 11, 9 and 14 were used as controls. For comparison, IgE cross-reactivity between the hazelnut allergens was investigated using sera from hazelnut allergic patients. RESULTS: Median percentages of cross-inhibitions between Ana o 1-3 were 84-99%. In comparison, medians of cross-inhibitions between hazelnut allergens were 33-62%. The IC50 values revealed the highest IgE affinity to Ana o 3 and Cor a 14. Hazelnut legumin Cor a 9 inhibited IgE-binding to Ana o 1, 2, and 3 with median percentages of 75%, 56%, and 48%, respectively. No cross-reactivity was observed between allergenic vicilins or between 2S albumins from cashew and hazelnut. In silico identified potentially cross-reactive peptides of Ana o 3 overlapped with previously reported IgE epitopes of all three allergens. CONCLUSIONS: IgE with high affinity to Ana o 3 that cross-reacts with the other two major non-homologous cashew nut allergens might be responsible for the high allergenic potency of cashew nut. These cross-reactive IgE comprises the major fraction of specific IgE in cashew allergic patients, and might be responsible for cross-reactivity between unrelated tree nuts.

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.

The lipid interaction capacity of Sin a 2 and Ara h 1, major mustard and peanut allergens of the cupin superfamily, endorses allergenicity.

BACKGROUND: Sin a 2 (11S globulin) and Ara h 1 (7S globulin) are major allergens from yellow mustard seeds and peanut, respectively. The ability of these two allergens to interact with lipid components remains unknown. OBJECTIVE: To study the capacity of Sin a 2 and Ara h 1 to interact with lipid components and the potential effects of such interaction in their allergenic capacity. METHODS: Spectroscopic and SDS-PAGE binding assays of Sin a 2 and Ara h 1 with different phospholipid vesicles and gastrointestinal and endolysosomal digestions in the presence or absence of lipids were performed. The capacity of human monocyte-derived dendritic cells (hmoDCs) to capture food allergens in the presence or absence of lipids, the induced cytokine signature, and the effect of allergens and lipids to regulate TLR2-L-induced NF-kB/AP-1 activation in THP1 cells were analyzed. RESULTS: Sin a 2 and Ara h 1 bind phosphatidylglycerol (PG) acid but not phosphatidylcholine (PC) vesicles in a pH-dependent manner. The interaction of these two allergens with lipid components confers resistance to gastrointestinal digestion, reduces their uptake by hmoDCs, and enhances their stability to microsomal degradation. Mustard and peanut lipids favor a proinflammatory environment by increasing the IL-4/IL-10 ratio and IL-1ß production by hmoDCs. The presence of mustard lipids and PG vesicles inhibits TLR2-L-induced NF-kB/AP-1 activation in THP1 cells. CONCLUSION: Sin a 2 and Ara h 1 interact with lipid components, which might well contribute to explain the potent allergenic capacity of these two clinically relevant allergens belonging to the cupin superfamily.

IgE, IgG4 and IgA specific to Bet v 1-related food allergens do not predict oral allergy syndrome.

BACKGROUND: Birch pollen-associated plant food allergy is caused by Bet v 1-specific IgE, but presence of cross-reactive IgE to related allergens does not predict food allergy. The role of other immunoglobulin isotypes in the birch pollen-plant food syndrome has not been investigated in detail. METHODS: Bet v 1-sensitized birch pollen-allergic patients (n = 35) were diagnosed for food allergy by standardized interviews, skin prick tests, prick-to-prick tests and ImmunoCAP. Concentrations of allergen-specific IgE, IgG1, IgG4 and IgA to seven Bet v 1-related food allergens were determined by ELISA. RESULTS: Bet v 1, Cor a 1, Mal d 1 and Pru p 1 bound IgE from all and IgG4 and IgA from the majority of sera. Immunoglobulins to Gly m 4, Vig r 1 and Api g 1.01 were detected in <65% of the sera. No significant correlation was observed between plant food allergy and increased or reduced levels of IgE, IgG1, IgG4 or IgA specific to most Bet v 1-related allergens. Api g 1-specific IgE was significantly (P = 0.01) elevated in celeriac-allergic compared with celeriac-tolerant patients. Likewise, frequencies of IgE (71% vs 15%; P = 0.01) and IgA (86% vs 38%; P = 0.04) binding to Api g 1.01 were increased. CONCLUSION: Measurements of allergen-specific immunoglobulins are not suitable for diagnosing Bet v 1-mediated plant food allergy to hazelnut and Rosaceae fruits. In contrast, IgE and IgA to the distantly related allergen Api g 1 correlate with allergy to celeriac.

Update of the WHO/IUIS Allergen Nomenclature Database based on analysis of allergen sequences.

The IUIS Allergen Nomenclature Sub-Committee, under the auspices of the World Health Organization and the International Union of Immunological Societies, maintains the systematic nomenclature of allergenic proteins and publishes a database of approved allergen names on its Web site, www.allergen.org. In this paper, we summarize updates of allergen names approved at the meetings of the committee in 2011 through 2013. These changes reflect recent progress in identification, cloning, and sequencing of allergens. The goals of this update were to increase consistency in the classification of allergens, isoallergens, and variants and in the incorporation of the evolutionary classification of proteins into allergen nomenclature, while keeping changes of established names to a minimum in the interest of continuity. Allergens for which names have been updated include respiratory allergens from birch and ragweed pollen, midge larvae, and horse dander; food allergens from peanut, cow's milk, and tomato; and cereal grain allergens. The IUIS Allergen Nomenclature Sub-Committee encourages researchers to use these updated allergen names in future publications.

¹H, ¹³C and ¹5N resonance assignments and second structure information of Gad m 1: a ß-parvalbumin allergen from Atlantic cod (Gadus morhua).

Gad m 1 is the major allergen from Atlantic cod. It belongs to ß-parvalbumin protein family and is characterized by the presence of two calcium-binding sites so called EF-hand motifs. ß-Parvalbumins such as Gad m 1 are the most important fish allergens and their high cross-reactivity is the cause of the observed polysensitization to various fish species in allergic patients. Despite extensive efforts, the complete elucidation of ß-parvalbumin-IgE complexes has not been achieved yet. Allergen structural studies are essential for the development of novel immunotherapy strategies, including vaccination with hypoallergenic derivatives and chimeric molecules. Here, we report for the first time the NMR study of a ß-parvalbumin: Gad m 1. This report includes: (1)H, (13)C and (15)N resonance assignments of Gad m 1 as well as the second structure information based on the (13)C chemical shifts.

Kiwifruit Act d 11 is the first member of the ripening-related protein family identified as an allergen.

BACKGROUND: Kiwifruit is an important cause of food allergy. A high amount of a protein with a molecular mass compatible with that of Bet v 1 was observed in the kiwifruit extract. OBJECTIVE: To identify and characterize kirola, the 17-kDa protein of green kiwifruit (Act d 11). METHODS: Act d 11 was purified from green kiwifruit. Its primary structure was obtained by direct protein sequencing. The IgE binding was investigated by skin testing, immunoblotting, inhibition tests, and detection by the ISAC microarray in an Italian cohort and in selected Bet v 1-sensitized Austrian patients. A clinical evaluation of kiwi allergy was carried out. RESULTS: Act d 11 was identified as a member of the major latex protein/ripening-related protein (MLP/RRP) family. IgE binding to Act d 11 was shown by all the applied testing. Patients tested positive for Act d 11 and reporting symptoms on kiwifruit exposure were found within the Bet v 1-positive subset rather than within the population selected for highly reliable history of allergic reactions to kiwifruit. Epidemiology of Act d 11 IgE reactivity was documented in the two cohorts. IgE co-recognition of Act d 11 within the Bet v 1-like molecules is documented using the microarray IgE inhibition assay. CONCLUSIONS: Act d 11 is the first member of the MLP/RRP protein family to be described as an allergen. It displays IgE co-recognition with allergens belonging to the PR-10 family, including Bet v 1.

The performance of a component-based allergen microarray for the diagnosis of kiwifruit allergy.

BACKGROUND: Allergy to kiwifruit is increasingly reported across Europe. Currently, the reliability of its diagnosis by the measurement of allergen-specific IgE with extracts or by skin testing with fresh fruits is unsatisfying. OBJECTIVE: To evaluate the usefulness of a component-based allergen microarray for the diagnosis of kiwifruit allergy in a large group of patients. METHODS: With an allergen microarray, we measured specific IgE and IgG4 levels to a panel of nine kiwifruit allergens in sera of 237 individuals with kiwifruit allergy. Sera from 198 allergic patients without kiwifruit allergy served as controls. Furthermore, we determined the extent of sensitization to latex. RESULTS: The panel of kiwifruit allergens showed a diagnostic sensitivity of 66%, a specificity of 56% and a positive predictive value of 73%. Sera from kiwifruit-allergic patients contained significantly more frequently Act d 1-specific IgE than sera from control patients. Furthermore, 51% of the positive sera contained IgE directed to a single allergen, namely Act d 1 (45%), Act d 9 (27%) or Act d 7 (13%). Within the control group, 36% sera recognized a single allergen. Out of those, 48% were positive to the cross-reactive glycoallergen Act d 7, 43% to the profilin Act d 9 and only 5% to Act d 1. Allergen-specific IgG4 levels did not differ between kiwifruit-allergic and -tolerant patients. Kiwifruit- and latex-allergic patients contained Hev b 11-specific IgE significantly more frequently than latex-allergic patients without kiwifruit allergy. CONCLUSIONS: Act d 1 can be considered a marker allergen for genuine sensitization to kiwifruit. We demonstrated that a component-based kiwifruit allergen microarray would improve the prognostic value of in vitro diagnostic tests.

Bet v 1 and its homologous food allergen Api g 1 stimulate dendritic cells from birch pollen-allergic individuals to induce different Th-cell polarization.

BACKGROUND: Bet v 1 is the most relevant sensitizing protein for birch pollen (BP)-allergic individuals. Its homologues from plant foods are mainly involved in allergic reactions caused by IgE cross reactivity. We aimed to evaluate the polarizing effect of dendritic cells (DCs) pulsed with Bet v 1, Mal d 1, Api g 1 or Dau c 1 on Th-cell responses. METHODS: Immature DCs were generated from peripheral blood monocytes of BP-allergic and healthy donors by culture with GM-CSF and IL-4 and subsequently pulsed with allergens in combination with maturation factors. Cell surface markers were analysed by FACS. Mature DCs were co-cultured with autologous Th cells and T-cell proliferation and cytokine profiles were determined. RESULTS: In co-culture, mature allergen-pulsed DCs induced autologous Th cells of BP-allergic donors to proliferate significantly more than those of healthy individuals. Exposure of DCs from BP-allergic donors to Bet v 1 resulted in a robust Th2 skewing with significantly higher quantities of IL-5 and elevated IL-13 compared to maturation factors. In contrast, Api g 1-primed DCs from BP allergics significantly enhanced the production of the Th1 cytokine IFN-γ and significantly down-regulated IL-13 compared to maturation factors. In healthy donors, no significant cytokine production could be detected. CONCLUSION: Bet v 1 in contrast to homologous food allergens seems to possess distinct molecular features that enable it to condition DCs from BP-allergic donors to induce allergen-specific T-cell proliferation and Th2 polarization.

Expression levels of parvalbumins determine allergenicity of fish species.

BACKGROUND: Parvalbumins are the most important fish allergens. Polysensitization to various fish species is frequently reported and linked to the cross-reactivity of their parvalbumins. Studies on cross-reactivity and its association to the allergenicity of purified natural parvalbumins from different fish species are still lacking. In addition, some studies indicate that dark muscled fish such as tuna are less allergenic. METHODS: Total protein extracts and purified parvalbumins from cod, whiff, and swordfish, all eaten frequently in Spain, were tested for their IgE-binding properties with 16 fish allergic patients' sera from Madrid. The extent of cross-reactivity of these parvalbumins was investigated by IgE ELISA inhibition assays. Additionally, the cDNA sequences of whiff and swordfish parvalbumins were determined. RESULTS: Extractable amounts of parvalbumins from cod were 20 times and from whiff 30 times higher than from swordfish. Parvalbumins were recognized by 94% of the patients in extracts of cod and whiff, but only by 60% in swordfish extracts. Nevertheless, a high cross-reactivity was determined for all purified parvalbumins by IgE inhibition. The amino acid sequence identities of the three parvalbumins were in a range of 62-74%. CONCLUSIONS: The parvalbumins of cod, whiff and swordfish are highly cross-reactive. The high amino acid sequence identity among cod, whiff and swordfish parvalbumins results in the observed IgE cross-reactivity. The low allergenicity of swordfish is due to the low expression levels of its parvalbumin.

Factors influencing the incidence and prevalence of food allergy.

Food allergy is an increasing problem in Europe and elsewhere and severe reactions to food are also becoming more common. As food allergy is usually associated with other forms of allergic sensitisation it is likely that many risk factors are common to all forms of allergy. However the potential severity of the disease and the specific public heath measures required for food allergy make it important to identify the specific risk factors for this condition. Food allergy is unusual in that it often manifests itself very early in life and commonly remits with the development of tolerance. Hypotheses that explain the distribution of food allergy include specific genetic polymorphisms, the nature of the allergens involved and the unique exposure to large quantities of allergen through the gut. Progress has been made in developing more specific and testable hypotheses but the evidence for any of these is still only preliminary. Further collaborative research is required to develop an appropriate public health response to this growing problem.

Generation of allergen-enriched protein fractions of Hevea brasiliensis latex for in vitro and in vivo diagnosis.

BACKGROUND: The latex of Hevea brasiliensis trees contains a complex proteome that includes a range of allergenic proteins. Current latex extracts that are used for the diagnosis of latex allergy still lack important allergens. We aimed to devise a production process for an improved reagent that would ideally contain the complete latex allergome. METHODS: Latex C-serum was fractionated by ammonium sulfate precipitation, and B- and C-serum proteins were then separated by anion exchange chromatography. Proteins eluting within defined salt concentration ranges were pooled into six final fractions. Fractions were evaluated by two-dimensional electrophoresis and subsequent IgE immunoblot for their spectrum of allergens. The presence of the most important latex allergens in the fractions was checked by Western blot analyses. Each fraction was further evaluated by skin prick test (SPT). RESULTS: Reproducibility of the preparation method was demonstrated with two batches of latex. Comparison of latex B- and C-serum to the six fractions showed a remarkable increase in the number of detectable allergens in the fractions. The presence of the latex allergens Hev b 1-8 and Hev b 13 in the fractions was demonstrated. In SPTs, the fractions produced wheal-and-flare reactions comparable to commercial latex extracts. CONCLUSIONS: This method provides reproducible latex protein fractions of high allergen content for the diagnosis of latex allergy.

A recombinant allergen chimer as novel mucosal vaccine candidate for prevention of multi-sensitivities.

BACKGROUND: As conventional immunotherapy is less efficacious in patients with allergic multi-sensitivities compared with mono-sensitized subjects, new intervention strategies are needed. Therefore, an allergen chimer was genetically engineered for treatment of multi-sensitization with birch and grass pollen on the basis of mucosal tolerance induction. METHODS: The major birch pollen allergen Bet v 1 served as a scaffold for N- and C-terminal linkage of the immunodominant peptides of the grass pollen allergens Phl p 1 and Phl p 5 and this new construct was cloned and expressed in Escherichia coli. After purification, physicochemical and immunological characterization the chimer was used for intranasal tolerance induction prior to poly-sensitization with Bet v 1, Phl p 1 and Phl p 5. RESULTS: The immunological characterization revealed that the conformation of Bet v 1 within the chimer was comparable to that of natural as well as recombinant Bet v 1. The chimer was immunogenic in mice for T and B cell responses to the three allergens. Intranasal application of the chimer prior to poly-sensitization significantly suppressed humoral and cellular allergen-specific Th2 responses and prevented development of airway inflammation upon allergen challenge. Moreover, local allergen-specific IgA antibodies were induced by the chimer. The mechanisms of poly-tolerance induction seemed to be mediated by regulatory cytokines, since TGF-beta and IL-10 mRNA in splenocytes were upregulated and tolerance was transferable with these cells. CONCLUSION: The data indicate that such allergen chimers harboring several unrelated allergens or allergen peptides could serve as mucosal polyvalent vaccines for prevention of multi-sensitivities.

Allergen concentration in natural rubber latex.

BACKGROUND: Hevea brasiliensis latex serum is commonly used as the in vivo and in vitro reference antigen for latex allergy diagnosis as it contains the full complement of latex allergens. OBJECTIVE: This study quantifies the concentrations of the significant allergens in latex serum and examines its suitability as an antigen source in latex allergy diagnosis and immunotherapy. METHODS: The serum phase was extracted from centrifuged latex that was repeatedly freeze-thawed or glycerinated. Quantitation of latex allergens was performed by two-site immunoenzymetric assays. The abundance of RNA transcripts of the latex allergens was estimated from the number of their clones in an Expressed Sequence Tags library. RESULTS: The latex allergens, Hev b 1, 2, 3, 4, 5, 6, 7 and 13, were detected in freeze-thawed and glycerinated latex serum at levels ranging from 75 (Hev b 6) to 0.06 nmol/mg total proteins (Hev b 4). Hev b 6 content in the latex was up to a thousand times higher than the other seven latex allergens, depending on source and/or preparation procedure. Allergen concentration was reflected in the abundance of mRNA transcripts. When used as the antigen, latex serum may bias the outcome of latex allergy diagnostic tests towards sensitization to Hev b 6. Tests that make use of latex serum may fail to detect latex-specific IgE reactivity in subjects who are sensitized only to allergens that are present at low concentrations. CONCLUSION: Latex allergy diagnostics and immunotherapy that use whole latex serum as the antigen source may not be optimal because of the marked imbalance of its constituent allergens.

Characterization of recombinant Mal d 4 and its application for component-resolved diagnosis of apple allergy.

BACKGROUND: Profilins are ubiquitous panallergens that have been extensively characterized; yet, their clinical relevance is still unclear. OBJECTIVE: The aim of the present study was to produce recombinant apple profilin (rMal d 4) and to evaluate its allergenic activity and its potency for component-resolved allergy diagnosis. METHODS: Complementary DNA-derived Mal d 4 was cloned, expressed in Escherichia coli and subsequently purified via poly (l-proline) sepharose. A total of 28 sera from apple-allergic patients were used for IgE-ELISA, immunoblot, RAST and basophil histamine release (BHR) test. In addition, skin prick tests (SPTs) were performed in five patients. RESULTS: Four different complementary DNA coding for apple profilin, Mal d 4, each with an open reading frame of 393 nucleotides, were identified. One isoform Mal d 4.0101 was expressed in Escherichia coli and subsequently purified. Mass spectroscopy revealed the expected mass of 13.826 for rMal d 4.0101, and circular dichroism analysis data were typical for a folded protein and small-angle X-ray scattering measurement identified the protein as a monomer. All the serum samples displayed IgE binding to rMal d 4.0101 in IgE ELISA, immunoblot and RAST. In immunoblotting, IgE binding to natural Mal d 4 was partially/completely inhibited by preincubation with rMal d 4.0101, and RAST values to apple extract were significantly reduced upon serum pretreatment with rMal d 4.0101. SPTs and BHR assays using purified rMal d 4.0101 were positive. Purified rMal d 4.0101 was destroyed within seconds when subjected to pepsin digestion. CONCLUSIONS: Apple profilin complementary DNAs were identified. The physicochemical and allergenic properties of purified recombinant Mal d 4.0101 were evaluated showing that the recombinant protein was equal to the natural protein as shown by inhibition assays. Thus, Mal d 4 represents another example suitable for component-resolved diagnosis of food allergy.

Allergenicity assessment of apple cultivars: hurdles in quantifying labile fruit allergens.

BACKGROUND: Assessment of allergenicity of foods is important for allergic consumers and regulators. Immunoassays to measure major food allergens are widely applied, often giving variable results. Using the major apple allergen Mal d 1 as a model, we aimed to establish at the molecular level why different immunoassays for assessing allergenicity of apple cultivars produce conflicting outcomes. METHODS: Mal d 1 was measured in 53 cultivars from Italy and 35 from The Netherlands, using four different immunoassays. Purified Mal d 1 standards were molecularly characterized by size-exclusion chromatography (SEC) and mass spectrometry (MS). RESULTS: Three immunoassays using an identical standard gave similar results. Minor differences in sample preparation already resulted in significant loss of allergenicity. The fourth assay, using a different Mal d 1 standard, gave 10- to 100-fold lower outcomes. By SEC, this standard was shown to be almost fully aggregated. This aggregation was accompanied by a decrease of the mass of the Mal d 1 molecule by approximately 1 kDa as analyzed by MS. The deviating immunoassay was shown to selectively recognize this aggregated form of Mal d 1, whereas the other three assays, including the one based on IgE antibody recognition, preferentially bound non-aggregated allergen. CONCLUSIONS: Variable and poorly controllable major allergen modification in both extracts and standards hamper accurate allergenicity assessments of fruits.

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.