Clinical reactivity of celery cultivars in allergic patients: Role of Api g 1.

BACKGROUND: Celery (Apium graveolens L.) is a vegetable consumed world-wide. Celery stalks and celeriac roots are often ingredients in convenient food products like spice blends and soups. OBJECTIVE: In this study, we examined the allergenicity of distinct celeriac cultivars. METHODS: Sixteen celery-allergic patients were identified using a double-blind, placebo-controlled food challenge. Ten different celeriac cultivars were used for skin prick testing in the patients. Two cultivars were further applied for oral food challenges; their protein composition was analysed by immunoblotting, and contents of major allergen Api g 1 were quantified. RESULTS: From the 10 investigated celeriac cultivars, two cultivars elicited significantly different skin reactivity ("Anita": 5.0 [2.0-12.0] mm vs "Prinz": 7.0 [3.0-9.5] mm; P = .047). Moreover, "Anita" induced fewer symptoms after a controlled oral-celeriac challenge in 14 patient (P < .001). The protein profiles on 2DE protein gels showed distinct protein patterns and higher protein amounts of Api g 1 in "Prinz" than in "Anita." CONCLUSIONS AND CLINICAL RELEVANCE: Taken together, the data from this study suggest that cultivar Anita is better tolerated in celery-allergic patients than "Prinz." Differences in the protein expression profile between the cultivars, particularly the different content of Api g 1, could cause the different allergenicity.

Detection of the food allergen celery via loop-mediated isothermal amplification technique.

Since 2005, celery and celery products have to be labeled according to Directive 2003/89/EC due to their allergenic potential. In order to provide a DNA-based, rapid and simple detection method suitable for high-throughput analysis, a loop-mediated isothermal amplification (LAMP) assay for the detection of celery (Apium graveolens) was developed. The assay was tested for specificity for celery since closely related species also hold food relevance. The limit of detection (LOD) for spiked food samples was found to be as low as 7.8 mg of dry celery powder per kilogram. An evaluation of different amplification and detection platforms was performed to show reliable detection independent from the instrument used for amplification (thermal cycler or heating block) and detection mechanisms (real-time fluorescence detection, agarose gel electrophoresis or nucleic acid staining). The analysis of 10 commercial food samples representing diverse and complex food matrices, and a false-negative rate of 0% for approximately 24 target copies or 0.08 ng celery DNA for three selected food matrices show that LAMP has the potential to be used as an alternative strategy for the detection of allergenic celery. The performance of the developed LAMP assay turned out to be equal or superior to the best available PCR assay for the detection of celery in food products.

Structure and function of the peanut panallergen Ara h 8.

The incidence of peanut allergy continues to rise in the United States and Europe. Whereas exposure to the major allergens Ara h 1, 2, 3, and 6 can cause fatal anaphylaxis, exposure to the minor allergens usually does not. Ara h 8 is a minor allergen. Importantly, it is the minor food allergens that are thought to be responsible for oral allergy syndrome (OAS), in which sensitization to airborne allergens causes a Type 2 allergic reaction to ingested foods. Furthermore, it is believed that similar protein structure rather than a similar linear sequence is the cause of OAS. Bet v 1 from birch pollen is a common sensitizing agent, and OAS results when patients consume certain fruits, vegetables, tree nuts, and peanuts. Here, we report the three-dimensional structure of Ara h 8, a Bet v 1 homolog. The overall fold is very similar to that of Bet v 1, Api g 1 (celery), Gly m 4 (soy), and Pru av 1 (cherry). Ara h 8 binds the isoflavones quercetin and apigenin as well as resveratrol avidly.

Allergenic relevance of nonspecific lipid transfer proteins 2: Identification and characterization of Api g 6 from celery tuber as representative of a novel IgE-binding protein family.

SCOPE: Apium graveolens represents a relevant food allergen source linked with severe systemic reactions. We sought to identify an IgE-binding nonspecific lipid transfer protein (nsLTP) in celery tuber. METHODS AND RESULTS: A low molecular weight protein exclusively present in celery tuber was purified and designated Api g 6. The entire protein sequence was obtained by MS and classified as member of the nsLTP2 family. Api g 6 is monomeric in solution with a molecular mass of 6936 Da. The alpha-helical disulfide bond-stabilized structure confers tremendous thermal stability (Tm > 90°C) and high resistance to gastrointestinal digestion. Endolysosomal degradation demonstrated low susceptibility and the presence of a dominant peptide cluster at the C-terminus. Thirty-eight percent of A. graveolens allergic patients demonstrated IgE reactivity to purified natural Api g 6 in ELISA and heat treatment did only partially reduce its allergenic activity. No correlation in IgE binding and limited cross-reactivity was observed with Api g 2 and Art v 3, nsLTP1 from celery stalks and mugwort pollen. CONCLUSION: Api g 6, a novel nsLTP2 from celery tuber represents the first well-characterized allergen in this protein family. Despite similar structural and physicochemical features as nsLTP1, immunological properties of Api g 6 are distinct which warrants its inclusion in molecule-based diagnosis of A. graveolens allergy.

Celery--cause of severe anaphylactic shock.

BACKGROUND: We present a case of anaphylactic shock induced by celery ingestion in a 28-year old woman with pollinosis during allergen (50% birch, 50% grass) immunotherapy. CASE REPORT: A female patient, aged 28 was admitted to the clinic due to a serious anaphylactic reaction. The event took place 15 min after ingesting fresh celery. She recovered after routine treatment with adrenaline, corticosteroids and antazoline. CONCLUSIONS: Our case shows the possibility of simultaneous occurrence of hypersensitivity to inhaled allergens and food. In such cases, it is considered part of cross-reactivity We discuss the importance of cross- reactivity associated with sensitization to pollen and vegetable foods.

Development of a standardized low-dose double-blind placebo-controlled challenge vehicle for the EuroPrevall project.

BACKGROUND: Double-blind placebo-controlled food challenge (DBPCFC) is the gold standard for diagnosing food allergy. Standardized materials and protocols are essential for comparing DBPCFC results for multicentre studies such as EuroPrevall. This required the development and piloting of a standardized vehicle and low-dose protocol for confirming food allergy and determination of minimum eliciting doses (MEDs). METHODS: A low-dose DBPCFC protocol was developed, with eight titrated protein doses from 3 µg to 1 g. This was delivered using a simple, microbiologically stable food base incorporating allergenic food ingredients manufactured at three sites and centrally distributed to clinical centres. Allergen blinding was assessed by a professional sensory testing panel using a triangle test. Homogeneity and allergen content were confirmed by ELISA and clinical efficacy was assessed in a pilot study, using celeriac and hazelnut as exemplars. RESULTS: Celeriac and hazelnut ingredients were sufficiently blinded in the dessert. The dessert meals were successfully piloted with hazelnut in allergy clinics in Spain, the Netherlands and Italy and with celeriac and hazelnut in Zurich. The challenges elicited a range of subjective and objective reactions ranging in severity from mild itching of the oral mucosa to bronchospasm. CONCLUSIONS: A standardized challenge vehicle proven to sufficiently blind processed, powdered hazelnut and celeriac ingredients and that can be reproducibly manufactured has been developed. This pilot study shows that the vehicle is promising for the confirmation of food allergy and determination of MEDs in adults and children with body weight >28.8 kg (approximately 7-11 years old).

Sensitization prevalence, antibody cross-reactivity and immunogenic peptide profile of Api g 2, the non-specific lipid transfer protein 1 of celery.

BACKGROUND: Celery (Apium graveolens) represents a relevant allergen source that can elicit severe reactions in the adult population. To investigate the sensitization prevalence and cross-reactivity of Api g 2 from celery stalks in a Mediterranean population and in a mouse model. METHODOLOGY: 786 non-randomized subjects from Italy were screened for IgE reactivity to rApi g 2, rArt v 3 (mugwort pollen LTP) and nPru p 3 (peach LTP) using an allergen microarray. Clinical data of 32 selected patients with reactivity to LTP under investigation were evaluated. Specific IgE titers and cross-inhibitions were performed in ELISA and allergen microarray. Balb/c mice were immunized with purified LTPs; IgG titers were determined in ELISA and mediator release was examined using RBL-2H3 cells. Simulated endolysosomal digestion was performed using microsomes obtained from human DCs. RESULTS: IgE testing showed a sensitization prevalence of 25.6% to Api g 2, 18.6% to Art v 3, and 28.6% to Pru p 3 and frequent co-sensitization and correlating IgE-reactivity was observed. 10/32 patients suffering from LTP-related allergy reported symptoms upon consumption of celery stalks which mainly presented as OAS. Considerable IgE cross-reactivity was observed between Api g 2, Art v 3, and Pru p 3 with varying inhibition degrees of individual patients' sera. Simulating LTP mono-sensitization in a mouse model showed development of more congruent antibody specificities between Api g 2 and Art v 3. Notably, biologically relevant murine IgE cross-reactivity was restricted to the latter and diverse from Pru p 3 epitopes. Endolysosomal processing of LTP showed generation of similar clusters, which presumably represent T-cell peptides. CONCLUSIONS: Api g 2 represents a relevant celery stalk allergen in the LTP-sensitized population. The molecule displays common B cell epitopes and endolysosomal peptides that encompass T cell epitopes with pollen and plant-food derived LTP.

Comparison of DNA extraction methods and development of duplex PCR and real-time PCR to detect tomato, carrot, and celery in food.

Traceability is of particular importance for those persons who suffer allergy or intolerance to some food component(s) and need a strict avoidance of the allergenic food. In this paper, methodologies are described to fingerprint the presence of allergenic species such as carrot, tomato, and celery by DNA detection. Three DNA extraction methods were applied on vegetables and foods containing or not containing the allergens, and the results were compared and discussed. Fast SYBR Green DNA melting curve temperature analyses and duplex PCR assays with internal control have been developed for detection of these allergenic vegetables and have been tested on commercial foods. Spiking food experiments were also performed, assessing that limits of detection (LOD) of 1 mg/kg for carrot and tomato DNA and 10 mg/kg for celery DNA have been reached.

Multiplex, quantitative, ligation-dependent probe amplification for determination of allergens in food.

Legislation requires labeling of foods containing allergenic ingredients. Here, we present a robust 10-plex quantitative and sensitive ligation-dependent probe amplification method, the allergen-multiplex ligation-dependent probe amplification (MLPA) method, for specific detection of eight allergens: sesame, soy, hazelnut, peanut, lupine, gluten, mustard, and celery. Ligated probes were amplified by polymerase chain reaction (PCR), and amplicons were detected using capillary electrophoresis. Quantitative results were obtained by comparing signals with an internal positive control. The limit of detection varied from approximately 5 to 400 gene copies, depending on the allergen. The method was tested using different foods spiked with mustard, celery, soy, or lupine flour in the 1-0.001% range. Depending on the allergen, sensitivities were similar or better than those obtained with qPCR. The allergen-MLPA method is modular and can be adapted by adding probe pairs for other allergens. The DNA-based allergen-MLPA method will constitute a complementary method to the traditional protein-based methods.

Molecular characterization of Api g 2, a novel allergenic member of the lipid-transfer protein 1 family from celery stalks.

SCOPE: Celery represents a relevant cross-reactive food allergen source in the adult population. As the currently known allergens are not typical elicitors of severe symptoms, we aimed to identify and characterize a non-specific lipid transfer protein (nsLTP). METHODS AND RESULTS: MS and cDNA cloning were applied to obtain the full-length sequence of a novel allergenic nsLTP from celery stalks. The purified natural molecule consisted of a single isoallergen designated as Api g 2.0101, which was recombinantly produced in Escherichia coli Rosetta-gami. The natural and recombinant molecules displayed equivalent physicochemical and immunological properties. Circular dichroism revealed a typical α-helical fold and high thermal stability. Moreover, Api g 2 was highly resistant to simulated gastrointestinal digestion. As assessed by ELISA, thermal denaturation did not affect the IgE binding of Api g 2. Natural and recombinant Api g 2 showed similar allergenic activity in mediator release assays. Api g 2-specific IgE antibodies cross-reacted with peach and mugwort pollen nsLTPs. CONCLUSION: Based on our results, it can be anticipated that inclusion of recombinant Api g 2 in the current panel of allergens for molecule-based diagnosis will facilitate the evaluation of the clinical relevance of nsLTP sensitization in celery allergy and help clinicians in the management of food allergic patients.

High-pressure treatment reduces the immunoreactivity of the major allergens in apple and celeriac.

SCOPE: The impact of thermal and high pressure (HP) processing on the immunoreactivity of the allergens Mal d 1, Mal d 3 and Api g 1 has been investigated in apple and celeriac tissue, respectively. METHODS AND RESULTS: The extracted proteins were assessed using SDS-PAGE and Western blot. The results showed that Mal d 1 was subject to loss of immunoreactivity as soon as the apple tissue was disrupted although it was remarkably resistant to both thermal and HP processing. This is in contrast to the Mal d 1 structural homolog from celeriac, Api g 1, that was susceptible to thermal processing. The other major allergen in apple, Mal d 3, was found to be resistant to chemical modification and thermal processing in apple, which is in contrast to behavior in solution. However, the combination of pressure and temperature significantly reduced its immunoreactivity. Pectin was found to protect Mal d 3 from thermal denaturation in solution and is a possible candidate for the protective effect of the fruit. CONCLUSION: The conclusion to be drawn from these results is that the combination of HP and thermal processing is an effective method to reduce the allergenicity of both apple and celeriac.

Identification of IgE binding to Api g 1-derived peptides.

Celery is a frequent cause of food allergy in pollen-sensitized patients and can induce severe allergic reactions. Clinical symptoms cannot be predicted by skin prick tests (SPTs) or by determining allergen-specific immunoglobulin E (IgE). Our aim was to identify specific IgE binding peptides by using an array technique. For our study, the sera of 21 patients with positive double-blind, placebo-controlled food challenge (DBPCFC) to celery, as well as the sera of 17 healthy patients were used. Additionally, all patients underwent skin tests along with determinations of specific IgE binding. The major allergen of celery Api g 1.0101 (Apium graveolens) was synthesized as an array of overlapping peptides and probed with the patients' sera. We developed an improved immunoassay protocol by investigating peptide lengths, peptide densities, incubation parameters, and readout systems, which could influence IgE binding. Sera of celery-allergic patients showed binding to three distinct regions of Api g 1.0101. The region including amino acids 100 to 126 of Api g 1.0101 is the most important region for IgE binding. This region caused a fivefold higher binding of IgE from the sera of celery-allergic patients compared to those of healthy individuals. In particular, one peptide (VLVPTADGGSIC) was recognized by all sera of celery-allergic patients. In contrast, no binding to this peptide was detected in sera of the healthy controls. Our improved assay strategy allows us to distinguish between celery-allergic and healthy individuals, but needs to be explored in a larger cohort of well-defined patients.

Assessment of component-resolved in vitro diagnosis of celeriac allergy.

BACKGROUND: Previous studies have demonstrated insufficient sensitivity of commercially available celeriac extract reagents in the diagnosis of celeriac allergy. OBJECTIVE: We sought to assess the diagnostic performance of specific IgE determination based on recombinant and purified natural celeriac allergens in comparison with an extract-based assay and to investigate interference by IgE to cross-reactive carbohydrate determinants and its biologic activity. METHODS: Twenty-four subjects with a positive double-blind, placebo-controlled food challenge result to celeriac; 20 atopic control subjects with birch pollen allergy who tolerated celeriac; and 20 nonatopic subjects were enrolled. IgE binding was investigated for celeriac allergens (rApi g 1.01, rApi g 4, and nApi g 5), extract reagents (celeriac, birch, mugwort, and timothy grass pollen), birch pollen allergens (rBet v 1 and rBet v 2), and cross-reactive carbohydrate determinants by means of ImmunoCAP analysis. Biologic activity of allergens was determined based on basophil mediator release. RESULTS: Component-resolved ImmunoCAP analysis considerably increased the sensitivity to detect celeriac-specific IgE by 20%. Sensitization to carbohydrate structures was detected in 38% of patients with celeriac allergy, and there was an excellent correlation between sensitization to the glycoprotein Api g 5 and isolated glycan. Positive results among atopic control subjects were mainly caused by protein allergens, whereas the effect of carbohydrate epitopes was marginal. The ability of allergens to induce mediator release decreased in the order Bet v 1 > Api g 1 > Api g 5, confirming the low biologic activity of IgE to carbohydrate epitopes. CONCLUSION: Component-resolved diagnosis allowed an increase in diagnostic sensitivity from 67% to 88% compared with extract-based diagnosis. Sensitization to Api g 5 was attributable to its glycan moieties but did not interfere with diagnostic specificity.

Predictive value of the sulfidoleukotriene release assay in oral allergy syndrome to celery, hazelnut, and carrot.

BACKGROUND: Patients sensitized to birch pollen frequently suffer from a food allergy to plant foods such as celery, carrots, or hazelnut. One of the main manifestations of birch pollen-related food allergy is the oral allergy syndrome. Skin tests and allergen-specific immunoglobulin (Ig) E determinations are poor predictors of such reactions when assessed by double-blind placebo-controlled food challenge (DBPCFC). OBJECTIVE: To investigate whether a cellular test based on leukotriene release from basophils, the cellular antigen stimulation test in combination with enzyme-linked immunosorbent assay (CAST-ELISA), is predictive of pollen-related food allergy. METHODS: Birch pollen-sensitized patients with positive DBPCFC to celery (n=21), hazelnut (n=15), and carrot (n=7) underwent skin tests along with determination of specific IgE and CAST-ELISA for the respective allergens. The results were compared with those of 24 birch pollen-sensitized patients with negative open food challenge to celery, hazelnut, and carrot. RESULTS: While skin prick tests had a sensitivity of 85%, 80%, and 29% for commercial extracts of celery, hazelnut, and carrot, respectively, prick testing with self-prepared extracts yielded sensitivities of 100%, 80%, and 100%, respectively. For specific IgE determinations, sensitivities were 71%, 73%, and 57%, respectively, and the respective specificities were 67%, 73%, and 60%. For CAST-ELISA with various sources and doses of allergens, the sensitivity varied from 71% to 95% for celery, 73% to 80% for hazelnut, and 43% to 86% for carrot. The respective specificities were 67% to 92%, 75% to 88%, and 77% to 91%. Analysis of the predictive value of CAST-ELISA with receiver operating characteristic curves showed that the results of the tests were more predictive of pollen-related food allergy than quantitative allergen-specific IgE determinations. CONCLUSIONS: CAST-ELISA is more specific than routine diagnostic tests for the diagnosis of pollen-related food allergy to celery, hazelnut, and carrot.

Production and characterization of an allergen panel for component-resolved diagnosis of celery allergy.

In celery a relevant food allergen source, three allergens have been identified so far: Api g 1 and Api g 4, and one glycosylated protein, Api g 5. For component-resolved food allergy diagnosis high amounts of well-defined allergens are needed. Depending on the individual celery allergen, protocols for heterologous production and purification from natural source, respectively, were established to obtain homogenous protein batches. Afterwards the purified recombinant allergens, Api g 1, Api g 4 and natural Api g 5 were characterized regarding their structural integrity and immunological activity. Therefore, several methods were applied. Proteins were identified by partial N-terminal sequencing, protein mass was verified by MS and sequence integrity by MALDI-TOF and N-terminal sequencing after tryptic digestion. Presence of isoforms in natural allergen preparations was identified by 2-DE. Secondary and tertiary structures were evaluated by circular dichroism (CD) spectroscopy and NMR analysis. Finally, IgE binding capacity was verified using selected sera from celery allergic patients in IgE immunoblots and IgE ELISA. These well-defined celery allergens will be used to prove the concept of component-resolved diagnosis and will contribute to improve food allergy diagnosis in the future.

Characterization of intrinsic and extrinsic risk factors for celery allergy in immunosenescence.

Recent studies indicated an underestimation of allergies in elderly. In our experimental food allergy model of protein feeding under acid-suppression we aimed to assess whether food allergy can be induced in immunosenescent mice. Furthermore, the impact of gastric digestion on celery allergenicity was evaluated in aged patients. Measurements of serum zinc and iron levels in senescent and adult BALB/c mice for definition of the nutritional status indicated a possible alteration of the immune response in the aged animals due to reduced zinc and iron levels. Feedings of mice with digestion-sensitive celery proteins under physiological gastric conditions induced IgG1 and IgG2a in the aged and preferentially IgG1 in the adult animals. In contrast, incomplete digestion due to acid-suppression rendered celery-specific IgE, positive skin tests and elevated IL-5 levels in both age groups. Also in aged celery allergic patients (mean age 72 years) properly digested celery showed decreased capacity to bind and crosslink IgE as evaluated by skin tests and IgE immunoblot. Thus, in the geriatric murine model, celery allergy was induced only if gastric digestion was hindered. Accordingly, gastric proteolysis decreased in vitro and in vivo IgE-reactivity against celery proteins in aged allergic patients.

Mutational epitope analysis and cross-reactivity of two isoforms of Api g 1, the major celery allergen.

For better understanding the cross-reactivity between the major birch pollen and celery allergens, Bet v 1 and Api g 1, respectively, putative epitope areas and structurally important positions for IgE-binding of the isoforms Api g 1.01 and Api g 1.02 were point mutated. The IgE binding capacities were measured in ELISA, the IgE cross-reactivity between the isoforms, mutants and Bet v 1 investigated by ELISA-inhibition experiments with serum pools from patients with confirmed celery allergy (DBPCFC). Api g 1.01 displayed a clearly higher frequency and capacity of IgE binding than Api g 1.02. In Api g 1.01, substitution of lysine against glutamic acid at amino acid position 44, a key residue of the Bet v 1 "P-loop", increased the IgE-binding properties. Structural instability due to proline insertion at position 111/112 resulted in loss of IgE binding of Api g 1.01, but not of Api g 1.02. Between Api g 1.01 and Api g 1.02 only partial cross-reactivity was seen. The data suggest that the IgE epitopes of the two isoforms are distinct and that in contrast to Api g 1.01, the "P-loop" region plays an important role for IgE binding of celery allergic subjects to Api g 1.02. Understanding and investigation of the molecular mechanisms in celery allergy is an important step to generate hypoallergenic proteins for safe and efficacious immunotherapy of food allergy.

The prevalence of positive reactions in the atopy patch test with aeroallergens and food allergens in subjects with atopic eczema: a European multicenter study.

BACKGROUND: The atopy patch test (APT) was proposed to evaluate IgE-mediated sensitizations in patients with atopic eczema (AE). OBJECTIVE: The prevalence and agreement with clinical history and specific IgE (sIgE) of positive APT reactions was investigated in six European countries using a standardized method. METHODS: A total of 314 patients with AE in remission were tested in 12 study centers on clinically uninvolved, non-abraded back skin with 200 index of reactivity (IR)/g of house dust mite Dermatophagoides pteronyssinus, cat dander, grass, and birch pollen allergen extracts with defined major allergen contents in petrolatum. Extracts of egg white, celery and wheat flour with defined protein content were also patch tested. APT values were evaluated at 24, 48, and 72 h according to the European Task Force on Atopic Dermatitis (ETFAD) guidelines. In addition, skin-prick test (SPT) and sIgE and a detailed history on allergen-induced eczema flares were obtained. RESULTS: Previous eczema flares, after contact with specific allergens, were reported in 1% (celery) to 34% (D. pteronyssinus) of patients. The frequency of clear-cut positive APT reactions ranged from 39% with D. pteronyssinus to 9% with celery. All ETFAD intensities occured after 48 and 72 h. Positive SPT (16-57%) and elevated sIgE (19-59%) results were more frequent. Clear-cut positive APT with all SPT and sIgE testing negative was seen in 7% of the patients, whereas a positive APT without SPT or sIgE for the respective allergen was seen in 17% of the patients. APT, SPT and sIgE results showed significant agreement with history for grass pollen and egg white (two-sided Pr > /Z/ < or = 0.01). In addition, SPT and sIgE showed significant agreement with history for the other aeroallergens. With regard to clinical history, the APT had a higher specificity (64-91% depending on the allergen) than SPT (50-85%) or sIgE (52-85%). Positive APT were associated with longer duration of eczema flares and showed regional differences. In 10 non-atopic controls, no positive APT reaction was seen. CONCLUSION: Aeroallergens and food allergens are able to elicit eczematous skin reactions after epicutaneous application. As no gold standard for aeroallergen provocation in AE exists, the relevance of aeroallergens for AE flares may be evaluated by APT in addition to SPT and sIgE. The data may contribute to the international standardization of the APT.

Protein quantification, sandwich ELISA, and real-time PCR used to monitor industrial cleaning procedures for contamination with peanut and celery allergens.

In the United States, peanut is one of the main sources of food allergens. Similarly, celery is a common allergenic food in Western Europe. Severe allergic reactions to both foods are common. Unexpected allergic reactions can occur after the consumption of celery- and peanut-free foods as a result of inadvertent cross-contaminations during manufacturing. Therefore, in cooperation with a flavor manufacturer, we monitored the cleaning process of slurry preparation equipment with regard to contaminations of follow-up products with celery and peanut compounds. Washing water samples taken after different cleaning steps and follow-up products were analyzed for the presence of celery and peanut traces with a celery-specific real-time polymerase chain reaction (PCR) and a peanut-specific sandwich enzyme-linked immunosorbent assay (ELISA). PCR and ELISA were compared with a nonspecific protein assay to evaluate whether the detection of protein traces can be a fast and cost-effective method for monitoring the effectiveness of wet cleaning procedures. Additionally, the allergenic potential of the celery and peanut mush, which were used as source material, were measured by a mediator release assay using a rat basophilic leukemia (RBL) cell line. In conclusion, the quantification of total protein in washing water was suitable for monitoring the cleaning process. Our study also revealed evidence that, in cases where wet cleaning is applicable, allergenic traces can be removed with high efficiency.