Sera Of Allergic Patients Research Articles

Contribution of Chemical Modifications and Structural Epitopes to IgE binding by Ara h 3

RATIONALE: Roasting peanut is likely to increase IgE binding to Ara h 3 by chemically modifying its epitopes. We compared IgE binding of roasted (Ro), structurally-intact raw (Ra) and structurally altered (SA) Ara h 3 and examined the stability & IgE binding to Ara h 3 in oligomeric form. METHODS: Western and slot blots were performed on Ara h 3 purified from Ra, Ro, and SA peanut and oligomeric Ara h 3 using sera from peanut allergic and peanut sensitized patients. Circular dichroism and fluorescence polarization analysis were utilized to assess secondary, tertiary and quaternary structure of Ara h 3. RESULTS: Majority of allergic patient sera IgE bound at a higher level to Ro than to the Ra or SA Ara h 3 (Ro > Ra > SA). While serum IgE of peanut allergic patients binds at higher levels to Ro than Ra Ara h 3, no significant differences were seen in secondary structure. The stability and IgE binding properties of oligomeric structures are higher in the Ara h 3 purified from roasted peanut. CONCLUSIONS: Recognition of chemical modifications rather than structural alterations are the major contributors to enhanced IgE binding by Ro Ara h 3. Ra Ara h 3 is bound at higher levels by IgE than SA Ara h 3, which implies that structural rather than linear epitopes are the major contributors to IgE binding. These findings may influence development of more specific diagnostic and therapeutic tools in the future.

IgE Binding Reactivity of Peptide Fragments of Bla g 4, a Major German Cockroach Allergen

Cockroaches have been recognized as a major cause of asthma. Bla g 4 is one of the most important German cockroach allergens. The aim of this study is to investigate IgE reactivity to the recombinant Bla g 4 (rBla g 4) in the sera of allergic patients and identify linear IgE binding epitope. For protein expression, full-length Bla g 4 (EF202172) was divided into 5 overlapping peptide fragments (E1: aa 1-100, E2: aa 34-77, E3: aa 74-117, E4: aa 114-156, and E5: aa 153-182). The full-length and 5 peptide fragments of Bla g 4 was generated by PCR and over-expressed in E. coli BL21 (DE3). The IgE binding reactivities of the full-length and peptide fragments were measured by ELISA using 32 serum samples of cockroach allergy. The sera of 8 patients (25%) reacted with rBla g 4. Four sera (100%) showed IgE-binding reactivity to full-length and peptide fragment 4, and 2 sera (50%) reacted with peptide fragment 2. One (20%) serum reacted with peptide fragment 3. The results of ELISA using overlapping recombinant fragments indicated that the epitope region was located at amino acid sequences 34-73 and 78-113, and major IgE epitope of Bla g 4 was located at amino acid sequences 118-152 of C-terminal. B-cell epitope analysis of German cockroach allergen Bla g 4 could contribute to the strategic development of more specific and potentially efficacious immunotherapy.

Conformational changes of Mal d 2, a thaumatin-like apple allergen, induced by food processing

Mal d 2, a thaumatin-like protein from apple was previously described to react to almost 75% of the apple allergic patient sera. Based on the molecular structure of this protein, the present study focused on the conformational stability of Mal d 2 in relation to in vitro IgE-binding under different physico-chemical conditions and proteolysis. The structural integrity of Mal d 2 was monitored using SDS–PAGE, Western blotting using polyclonal antibodies and human sera, fluorescence spectrometry and circular dichroism. Results confirmed the stability of Mal d 2. However, Mal d 2 was reactive to human serum IgEs mainly after reduction of disulphide bridges fixing the α-helical domain II. Contrary to previous assumptions, the current findings suggest that the allergenic epitopes of Mal d 2 are hidden inside the protein structure and none of the rigorous conditions applied in industrial juice processing or digestive proteolysis enhance or reduce the binding to IgE molecules.

2S Albumin Storage Proteins: What Makes them Food Allergens?

2S albumin storage proteins are becoming of increasing interest in nutritional and clinical studies as they have been reported as major food allergens in seeds of many mono- and di-cotyledonous plants. This review describes the main biochemical, structural and functional properties of these proteins thought to play a role in determining their potential allergenicity. 2S albumins are considered to sensitize directly via the gastrointestinal tract (GIT). The high stability of their intrinsic protein structure, dominated by a well-conserved skeleton of cysteine residues, to the harsh conditions present in the GIT suggests that these proteins are able to cross the gut mucosal barrier to sensitize the mucosal immune system and/or elicit an allergic response. The flexible and solvent-exposed hypervariable region of these proteins is immunodominant and has the ability to bind IgE from allergic patients´ sera. Several linear IgE-binding epitopes of 2S albumins spanning this region have been described to play a major role in allergenicity; the role of conformational epitopes of these proteins in food allergy is far from being understood and need to be investigated. Finally, the interaction of these proteins with other components of the food matrix might influence the absorption rates of immunologically reactive 2S albumins but also in their immune response.

Specific IgG antibodies (total and subclasses) against Saffron pollen: a study of their correlation with specific IgE and immediate skin reactions.

Saffron (Zaaferan), botanical name Crocus sativus, is the most expensive spice in the world. It is derived from the dried stigma and pistil of the purple saffron crocus flowers. Iran is the largest saffron producer accounting for more than 80% of the world's production. Saffron contains an aeroallergen that causes reactive respiratory allergic reactions in atopic subjects. IgG antibody to allergens in the serum of allergic patients is not routinely measured. In this study in order to find out more about mechanism of allergy against saffron pollen, specific antibodies (IgE and IgG, total and subclasses) in atopic subjects were assayed. We used an ELISA assay for measuring specific IgE and IgG against saffron pollen extract in the sera of 38 atopic subjects (test group) and 20 non allergic subjects (control group). The optical densities were compared between allergic subjects and non-allergic individuals. The prick test with saffron pollen extract was used to evaluate the cutaneous and specific antibody responses in the allergic subjects. The correlation was determined by statistical analysis. Specific saffron pollen IgE and IgG subclasses were found significantly higher in the allergic subjects than the control group. The immediate skin reaction was found positive in 70% of the test group. We report here, the existence of a positive correlation between specific IgE and skin reaction by prick test in atopic subjects (R= 0.433). A negative correlation between specific IgE and IgG4 subclass was also found (R= -0.576). These data may be useful to understand the mechanism of allergy to saffron and may help in clarifying clinical manifestations and to prevent IgE production as well as therapeutic application.

Evaluation of three human Fc(RI transfected RBL cell lines for identifying functional IgE-allergen interactions using peanut allergic patient sera

Evaluation of three human Fc(RI transfected RBL cell lines for identifying functional IgE-allergen interactions using peanut allergic patient sera

Engineered recombinant ovomucoid third domain can desensitize Balb/c mice of egg allergy

The purpose of this study was to determine the in vivo desensitization efficacy of a hypoallergenic variant of egg white ovomucoid third domain (DIII) in Balb/c mice model. We mapped the immunodominant B-cell epitopes of ovomucoid in Balb/c mice. A hypoallergenic ovomucoid third domain (GMFA) mutant isoform having ablated allergenicity against egg allergic patient's sera was used to desensitize DIII-sensitized Balb/c mice by intraperitoneal injections. Ovomucoid DIII generated high levels of plasma histamine and specific immunoglobulin (Ig)E levels, and increased Th2 type cytokine (IL-4). On the other hand, the allergic response of mice desensitized with the GMFA was found to be significantly inhibited and abrogated by prevention of anaphylaxis reactions, low histamine levels and increased Th1-type cytokine (INF-gamma). It was found that significantly higher levels of IL-10 and IL-12 were secreted in the desensitized group. Desensitization with the GMFA antigen also suppressed synthesis of DIII specific-IgE levels and enhanced specific IgG2a and IgG levels compared with the group treated with the DIII antigen. The present results indicated that hyposensitization with the GMFA can desensitize or down-regulate the allergic response in Balb/c mice and this hypoallergenic variant of ovomucoid DIII can shift an ongoing allergen-specific Th2 response towards a Th1 skewed response.

The N‐glycans of yellow jacket venom hyaluronidases and the protein sequence of its major isoform in Vespula vulgaris

Hyaluronidase (E.C. 3.2.1.35), one of the three major allergens of yellow jacket venom, is a glycoprotein of 45 kDa that is largely responsible for the cross-reactivity of wasp and bee venoms with sera of allergic patients. The asparagine-linked carbohydrate often appears to constitute the common IgE-binding determinant. Using a combination of MALDI MS and HPLC of 2-aminopyridine-labelled glycans, we found core-difucosylated paucimannosidic glycans to be the major species in the 43-45 kDa band of Vespula vulgaris and also in the corresponding bands of venoms from five other wasp species (V. germanica, V. maculifrons, V. pensylvanica, V. flavopilosa and V. squamosa). Concomitant peptide mapping of the V. vulgaris 43 kDa band identified the known hyaluronidase, Ves v 2 (SwissProt P49370), but only as a minor component. De novo sequencing by tandem MS revealed the predominating peptides to resemble a different, yet homologous, sequence. cDNA cloning retrieved a sequence with 58 and 59% homology to the previously known isoform and to the Dolichovespula maculata and Polistes annularis hyaluronidases. Close homologues of this new, putative hyaluronidase b (Ves v 2b) were also the major isoform in the other wasp venoms.

Expression and epitope analysis of the major allergenic protein Fag e 1 from buckwheat

Seeds of common buckwheat ( Fagopyrum esculentum) contain valuable nutritive substances but also allergenic proteins that cause hypersensitive reactions. Thus, the development of hypoallergenic buckwheat would make this important pseudo-cereal available to allergic people. A major allergenic protein of buckwheat is Fag e 1. We isolated the respective cDNA, coding for a 22 kDa protein, from a recently developed autogamous strain of common buckwheat and confirmed its immunoglobulin E (IgE)-binding activity using recombinant Fag e 1 and sera of allergic patients. The derived amino acid sequence from Fag e 1 cDNA was used to synthesize an overlapping peptide library on nitrocellulose membranes for the determination of the Fag e 1 epitopes. We identified eight epitopes and the critical amino acids for IgE-binding within the epitopes. This epitope analysis of a major allergenic protein of buckwheat should help therapeutic efforts and aid in the development of hypoallergenic buckwheat.

Molecular characterization of a 10‐kDa buckwheat molecule reactive to allergic patients’ IgE

Using the sera from buckwheat (BW)-allergic patients, several putative causative molecules were reported. However, few molecules were determined on the molecular structure. We demonstrated in 2000 that the major allergen with 24 kDa (BW24KD) is a legumin-like storage protein. The aim of this study was to isolate and characterize further a major allergen with 10 kDa by molecular cloning. Buckwheat allergens were identified by immunoblotting analysis using sera from 14 allergic and two nonallergic individuals. We identified a protein with 10 kDa (BW10KD) that reacted with immunoglobulin E (IgE) more strongly than with IgG and IgA in 57% of the allergic patients but not with IgE in nonallergic individuals. Analyses were performed by N-terminal amino acid sequencing and molecular cloning. Physiological significance was assessed by an immunoblotting experiment showing that the reactivity of an allergic patient's serum IgE to BW10KD was competitively inhibited by natural BW extracts. Molecular cloning experiments indicated that BW10KD as a BW allergen was a member of the 2S-albumin multigene family.

Monoclonal IgE antibodies against birch pollen allergens: Novel tools for biological characterization and standardization of allergens

Background: IgE antibodies are key players in immediate hypersensitivity reactions. Allergen characterization and standardization is usually based on the sera of allergic patients, whereas monoclonal IgE antibodies specific for clinically relevant allergens are very rare. Objective: The aim of this study was to establish IgE mAbs specific for birch pollen allergens, because these are important inhalant allergens. Methods: IgE-producing hybridomas were identified by using the highly sensitive rat basophilic leukemia cell mediator release assay with enhanced allergen stimulation by additional cross-linking with birch pollen–specific IgG antibodies. The obtained IgE mAbs were characterized by immunologic methods and by cDNA sequencing. Results: Seven IgE mAbs specific for the birch pollen allergens Bet v 1 or Bet v 6 were obtained and were all biologically active in mast cell-based assays. Mediator release experiments with mAb combinations indicated that 2 different epitope regions were recognized on Bet v 1, whereas the 2 Bet v 6-specific mAbs bound to the same epitope region. After sensitization of rat basophilic leukemia cells with IgE mAbs, different amounts of Bet v 1 or Bet v 6 were detected in commercial diagnostic allergen reagents, whereas sensitization with polyclonal IgE resulted in similar allergenic potency of all products. Conclusions: IgE mAbs represent promising novel tools for allergen characterization and component-resolved standardization of allergen extracts. (J Allergy Clin Immunol 2003; 111:1262-8.)

Increased apoptosis of peripheral blood mononuclear cells in patients with perennial allergic asthma/rhinitis: relation to serum markers of apoptosis.

BACKGROUND: The goal of our study was to examine spontaneous and stimulated apoptosis of peripheral blood MNC from allergic patients, sensitized to Der p I antigen as compared to cells from non-atopic subjects. Furthermore we aimed to investigate which populations of mononuclear cells (lymphocytes, monocytes) undergo the apoptosis and to determine relations between apoptosis and serum levels of sFas/APO-1, ICE/caspase-1 or TNF-alpha. METHODS: The study included 17 patients with perennial, allergic asthma and/or allergic rhinitis [6 male and 11 female; mean age 29,5 years; (range 15-49)]. Apoptosis was assessed by fluorescence technique and confirmed by flow-cytometric method and DNA ladder. Serum levels of sFas, ICE/caspase-1 or TNF-alpha were determined by immunoassays (ELISA). RESULTS: Apoptotic index of unfractionated mononuclear cells (MNC) and lymphocytes (but not monocytes) were significantly higher in allergic patients as compared to non-allergic subjects after 48 and 72 hours of culture (p<0.05). Incubation of cells with ConA (10 microg/ml) resulted in a significant increase in the proportion of apoptotic cells in all populations once the apoptotic index for MNC and lymphocytes (but not monocytes) was again significantly higher in allergic as compared to non-allergic subjects after 24, 48 and 72 hour of culture. In allergic patients, mean serum sFas level, was significantly lower then in non-allergic group (mean value 624.8 pg/ml +/- 25.67 versus 802.0 pg/ml +/- 31.91; p = 0.003) and in both groups sFas level correlated inversely with apoptosis of MNC. The mean ICE/caspase-1 concentration was significantly higher in sera of allergic patients as compared to non-allergic group (mean value 27.71 pg/ml +/- 3.79 vs 23.54 pg/ml respectively; p<0.01). ICE/caspase-1 levels in allergic patients correlated with apoptotic index of mononuclear cells (r = 0.57; p<0.001). CONCLUSIONS: An increased spontaneous and mitogen-induced apoptosis of MNC from peripheral blood of atopic patients as well as different serum levels of sFas and ICE/caspase-1 correlating with apoptosis, suggest different regulation of apoptotic process in peripheral blood mononuclear cells of patients with allergic asthma and/or rhinitis.

Occupational allergy to bumblebees: Allergens of Bombus terrestris

Background: With the increase in commercial vegetable production in greenhouses, occupational sensitization to bumblebee venom is becoming more common. Studies using sera from subjects thus sensitized allow evaluation of the allergenic specificity of bumblebee sensitization. Objective: The purposes of this study were to determine the degree of species group specificity of bumblebee venom allergens in sera of allergic patients and to investigate the structural basis of this specificity. Methods: Allergens were purified from bumblebee venom, studied serologically by direct binding and inhibition techniques, and characterized by enzyme analysis and amino acid sequencing. Three-dimensional models of the phospholipases were constructed and analyzed. Results:Bombus terrestris venom contains phospholipase A2, venom protease, hyaluronidase, and acid phosphatase allergens. The protease and phospholipase A2 allergens contain IgE-reactive epitopes that are different from those seen in Bombus pennsylvanicus , a North American species. Bumblebee phospholipase A2 is only 53% identical to honeybee phospholipase A2. The results of 3-dimensional modeling are consistent with the immunologic observations. Conclusions: Patients with primary bumblebee sensitization should be diagnosed and treated with venom from the appropriate species group of bumblebees. Bumblebee venom phospholipase A2 and protease are antigenically distinct from honeybee venom proteins. There are significant species group–specific epitopes on bumblebee venom proteins. (J Allergy Clin Immunol 2001;108:855-60.)

Characterisation of Horse Dander Allergen Glycoproteins Using Amino Acid and Glycan Structure Analyses

Separation of horse dander allergens using two-dimensional PAGE resulted in the identification of 16 proteins that react with allergic patient sera. A sensitive method has been developed for analysing the structures of the glycan chains of individual glycoprotein allergens transferred to blots following two-dimensional PAGE, and has allowed the structural identification of the glycan chains of the most abundant isoforms of Equ c 1, a glycosylated horse dander major allergen. The method involves separation of the allergens by two-dimensional PAGE, transfer to polyvinylidene difluoride membranes, release of the glycan chains using peptide N-glycosidase F, permethylation and mass spectrometric analysis of the derivatised glycans. The amino acid compositions of the 16 horse dander allergens separated by two-dimensional PAGE have been determined, allowing the identification of the various isoforms of Equ c 1. These results also confirmed that the two non-glycosylated major allergens, Equ c 2.0101 and Equ c 2.0102, belong to the lipocalin family, and support the idea that these two allergens are most probably isoforms of the same protein. The glycan structures identified using the mass spectrometric method are common biantennary and triantennary glycan chains. These carbohydrate moieties may have a role in the binding of IgE; however, it is more likely that the overall glycoprotein structure involving both the glycan and protein moieties, rather than the structure of the glycan chains alone, is responsible for eliciting allergic responses.

Characterization of a dodecapeptide containing a dominant epitope of Par j 1 and Par o 1, the major allergens of P. judaica and P. officinalis pollen

The pollen of Parietaria, a weed of the Urticaceae family, is a major cause of respiratory allergy in Europe, where the most common species are P. judaica and P. officinalis. Previously, we reported that a beta-galactosidase fusion protein (6a-BG) expressing a 26-bp cDNA fragment (6a cDNA) contained a dominant IgE-binding epitope (6a epitope) of the major allergens Par o 1 and Par j 1. The present study aimed to define the amino-acid sequence containing the 6a epitope. We analyzed the reactivity of anti-Par o 1 antibodies affinity purified from allergic patient sera with: 1) a panel of synthetic peptides deduced from the 6a nucleotide sequence using different reading frames 2) glutathione S-transferase (GST) fusion proteins containing selected peptides. The peptide NSARARADSCRI (p102) specifically bound anti-Par o 1 antibodies affinity purified from allergic patient sera or from rabbit anti-Par o 1 antiserum (ELISA). The related peptide NSARAGTSSCRI (p101) reacted to human but not to rabbit, anti-Par o 1 antibodies. GST fusion proteins containing p101 (GST 3.5) or p102 (GST 3.2) extensively inhibited the binding between Par o 1 and IgE or IgG antibodies from an allergic patient serum pool according to a dose-response curve. Percent inhibition of IgE antibodies binding obtained by absorbing a solution (50 microl) of affinity-purified antibodies with 5 microg of GST 3.2 or with 1.2 mg of GST 3.5 was 69% and 66%, respectively. In conclusion, the results of the present study indicate that the amino-acid sequences NSARARADSCRI (p102) and NSARAGTSSCRI (p101) contain the dominant epitope of Par o 1 and Par j 1 for human IgE and IgG antibodies indicated as 6a epitope. Moreover, the study shows that the epitope is conserved in recombinant molecules containing these peptides, irrespective of the fused polypeptide (beta-galactosidase or GST). The knowledge of the amino-acid sequence of this dominant epitope is important in therapeutic approaches to the development of allergen-derived haptens.

Production and detailed characterization of biologically active olive pollen allergen Ole e 1 secreted by the yeast Pichia pastoris.

The glycoprotein Ole e 1 is a significant aeroallergen from the olive tree (Olea europaea) pollen, with great clinical relevance in the Mediterranean area. To produce a biologically active form of recombinant Ole e 1, heterologous expression in the methylotrophic yeast Pichia pastoris was carried out. A cDNA encoding Ole e 1, fused to a Saccharomyces cerevisiae alpha-mating factor prepropeptide using the pPIC9 vector, was inserted into the yeast genome under the control of the AOX1 promoter. After induction with methanol, the protein secreted into the extracellular medium was purified by ion-exchange and size-exclusion chromatography. The structure of the isolated recombinant Ole e 1 was determined by chemical and spectroscopic techniques, and its immunological properties analysed by blotting and ELISA inhibition with Ole e 1-specific monoclonal antibodies and IgE from sera of allergic patients. The allergen was produced at a yield of 60 mg per litre of culture as a homogeneous glycosylated protein of around 18.5 kDa. Recombinant Ole e 1 appears to be properly folded, as it displays spectroscopic properties (CD and fluorescence) and immunological reactivities (IgG binding to monoclonal antibodies sensitive to denaturation and IgE from sera of allergic patients) indistinguishable from those of the natural protein. This approach gives high-yield production of homogeneous and biologically active allergen, which should be useful for scientific and clinical purposes.

Serum Fcεrii Receptor (SCD23) as an Evaluating Factor for Grass Pollen Immunotherapy

CD23 is a protein on the surface of certain hemopoietic cells and it is considered to be the low affinity receptor for immunoglobulin IgE, (FcεRll/CD23). The regulation of the expression of CD23 depends on the type of cell on which it is found. Like most of the FcR receptors, it is released in a soluble form (sCD23) in the extracellular fluid. This form is found in increased levels in the serum of allergic patients and in neoplastic diseases. We studied total IgE and sCD23 in the serum of 30 allergic patients undergoing immunotherapy, 15 allergic patients treated only symptomatically for grass pollen (GP) allergy, 15 healthy and subjects. We found that the mean values of total IgE and sCD23 after the course of hyposensitization were decreased compared to those before treatment as well as to those GP allergic patients under conventional therapy and to healthy adults. However, only the CD23 decrease was statistically significant. Therefore, we speculate that determination of sCD23 may be useful for (a) the general evaluation of allergic patients and (b) the immunological monitoring of patients under immunotherapy.

Identification of the major allergens in wheat flour responsible for baker's asthma.

Baker's asthma, a typical occupational allergic disease, is a serious problem in the food industries. In this study, purification and identification of major allergens recognized by IgEs in sera of allergic patients were performed. Major immunoreactive proteins were purified from the albumin fraction by gel filtration on a Toyopearl HW-50 column followed by reverse-phase HPLC. The N-terminal amino acid sequences and molecular masses measured by MS indicated that the major immunoreactive proteins are members of the alpha-amylase inhibitor family, 0.19 and 0.28. Significant leukotriene release by each purified protein was observed in cell-associated stimulation tests, suggesting in vivo activity of these antigens. Carbohydrate analyses of major allergens indicated that they are monoglycosylated but not N-glycosylated in spite of the presence of a potential N-glycosylation site. Recombinant 0.19 expressed in Escherichia coli showed the same reactivity with IgE as native wheat 0.19 in Western blotting and ELISA using methyl vinyl ether maleic anhydride co-polymer as an immobilizing reagent, suggesting that the allergenic epitopes are located in the peptide portions.

Complement activating agents in allergenic extracts.

Extracts of environmental allergens, moulds and plant pollens are known to consume haemolytic complement (huC) in human serum in vitro through the antibody-independent engagement of the first component C1 of the classical pathway. The present work was undertaken to establish the nature and characteristics of the complement activating agents in allergenic extracts and to probe their relationship with the IgE-binding allergens. A large series of different > 10 kDa allergenic products was investigated for their capacity to consume haemolytic complement in the sera of allergic patients with specific anti-allergen IgE antibodies, as well as in normal control sera. UV-spectroscopy was used for categorizing the non-protein components in the extracts. The experiments confirmed that huC is consumed in an antibody-independent fashion and in a qualitatively similar, but quantitatively distinct manner. The ratio of the complement activating potencies among the different allergenic preparations thereby remained constant and independent of the serum source, while an overt relationship with specific IgE-antibodies could not be established. UV-spectroscopy of the allergenic preparations revealed the presence of chemical decomposition products in nearly every extract and roughly in proportion to the complement activating potencies. The data support the idea that huC-activation by traditional allergenic extracts is mainly due to by-stander degradation products of the melanoidin (Maillard) or tannin type, which may or may not occur in physical association with the IgE-binding protein allergens.

In Vitro study of the gastrointestinal stability of celery allergens

The gastrointestinal stability of proteins and allergens from native celery roots was studied by a simple two‐step in vitro procedure. Commercial enzyme tablets that contained peptic and pancreatic enzymes were used to simulate gastric and duodenal conditions respectively. The influence on the whole protein pattern was monitored by SDS‐PAGE. The antigenicity and allergenicity of the three known important allergenic structures of celery were investigated with IgG from two rabbit antisera, IgE from sera of allergic patients with known specificity for individual allergens, and by a mediator release assay utilizing allergen‐specific polyclonal murine IgE. The following allergens were studied: (i) Api g 1, a 16‐kDa celery protein which shares high sequence identity with the major birch pollen allergen. Bet v 1, (ii) celery profilin that belongs to a group of ubiquitous ‘plant pan allergens’ and (Hi) ubiquitous carbohydrate determinants present in many glycans of plant proteins in the mass range of 35–90 kDa. SDS‐PAGE indicated degradation of many proteins under gastric conditions, but immunoblotting showed only a weak influence on the antigenicity and IgE reactivity of the allergens. The protein degradation was clearly enhanced after 45 min of pancreatic digestion. To a weaker degree, all allergens were again recognized on immunoblots. The presence of a considerable residual allergenic activity which seems to resist even duodenal conditions was confirmed by the determination of human IgE specific for the digests using an Enzyme Allergosorbent Test. In addition, competitive IgE inhibition assays and measuring the celery‐induced mediator release of permanently growing RBL‐2H3 cells that had been passively sensitized with celery‐specific murine IgE showed similar results. The generation of small IgE binding peptides (≤ 3 kDa) was tested by ultrafiltration experiments. The whole IgE binding capacity was present in the retentates even after duodenal digestion. We concluded that, like many other allergens from foods and other sources, the allergens of native celery are relatively stable under gastrointestinal conditions and that the residual allergenic activity is mainly due to undigested allergens.