Randomized, double-blind, crossover challenge study in 53 subjects reporting adverse reactions to melon (Cucumis melo)

Clinical Relevance of Cross-Reactivity in Food Allergy

The diagnosis and management of food allergy is complicated by an abundance of homologous, cross-reactive proteins in edible foods and aeroallergens. This results in patients having allergic sensitization (positive tests) to many biologically related foods. However, many are sensitized to foods without exhibiting clinical reactivity. Although molecular diagnostics have improved our ability to identify clinically relevant cross-reactivity, the optimal approach to patients requires an understanding of the epidemiology of clinically relevant cross-reactivity, as well as the food-specific (degree of homology, protein stability, abundance) and patient-specific factors (immune response, augmentation factors) that determine clinical relevance. Examples of food families with high rates of cross-reactivity include mammalian milks, eggs, fish, and shellfish. Low rates are noted for grains (wheat, barley, rye), and rates of cross-reactivity are variable for most other foods. This review discusses clinically relevant cross-reactivity related to the aforementioned food groups as well as seeds, legumes (including peanut, soy, chickpea, lentil, and others), tree nuts, meats, fruits and vegetables (including the lipid transfer protein syndrome), and latex. The complicating factor of addressing co-allergy, for example, the risks of allergy to both peanut and tree nuts among atopic patients, is also discussed. Considerations for an approach to individual patient care are highlighted.

Extranasal Manifestations of Allergy in the Head and Neck

PURPOSE OF REVIEW

Allergic rhinitis and allergic asthma are well-described disease entities with broad exposure in clinical and research allergy forums. Associations between allergic inflammation and upper airway diseases of chronic laryngitis, otitis media, obstructive sleep apnea, and oral allergy syndrome are less well understood and described in the literature.

RECENT FINDINGS

This review discusses the relationship between atopy and diseases of the upper airway, oral cavity, larynx, and ear. The similar respiratory mucosal lining the upper aerodigestive tract, with sensitized mast cells and inflammatory mediators in the submucosa, results in a variety of extranasal manifestations of allergic diseases in the head and neck which are less well characterized. Associations between allergic inflammation and upper airway diseases of chronic laryngitis, otitis media, obstructive sleep apnea, and oral allergy syndrome are less well understood and described in the literature. This review will summarize the relevant pathophysiology and symptomology, association with allergic sensitization, and clinical considerations of these disorders.

Oral allergy syndrome

OBJECTIVES

To review oral allergy syndrome (OAS).

METHODS

We searched several medical literature data bases with the following key words: "oral allergy syndrome," "OAS," "pollen-food allergy syndrome," "PFAS," "allergy," "diagnosis," "treatment."

RESULTS

Oral allergy syndrome (OAS), also called "pollen-food allergy syndrome," is a type of food allergy brought about by flavors, nuts, raw fruit, and vegetables. The most well-known symptoms are mouth and throat itching, which starts rapidly after a food is placed in the mouth, and that, as a rule, continues for just a couple of minutes after the food has been swallowed. The frequency of OAS with pollen allergy has been reported as 5-8%; 1-2% of patients with OAS with pollen allergy show extreme responses, e.g., anaphylaxis. Birch tree pollen, ragweed pollen, and grass pollen hypersensitivity cause the symptoms. The diagnosis of OAS is confirmed by a positive history and positive skin-prick test result triggered by the food's fresh extract. Oral challenge result is normally positive with the raw food and negative with the similar cooked food.

CONCLUSION

Patients with grass allergy may have a response to peaches, oranges, celery, tomatoes, and melons. Patients with ragweed allergy may show OAS symptoms with melon, cucumber, banana, and zucchini. Physicians should be aware of OAS and know the appropriate treatment.

Pollen-food allergy syndrome is a common allergic comorbidity in adults with eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is associated with atopic diseases including asthma, allergic rhinitis, and atopic dermatitis; however, limited data exist on the correlation between pollen-food allergy syndrome (PFAS) and EoE. We analyzed 346 adults with EoE treated at a single center between 2002 and 2016. Demographic and EoE-specific data including clinical features and measures of EoE disease severity and treatments were collected. The presence of other atopic diseases, family history, prevalence of peripheral eosinophilia and elevated IgE, and details of PFAS triggers were collected. Twenty six percent of the 346 subjects in our cohort had both EoE and PFAS (EoE-PFAS). Compared to subjects with EoE alone, subjects with EoE-PFAS had an increased frequency of allergic rhinitis (86.7% vs. 64.2%, P < 0.001) and family history of allergies (71.1% vs. 53.3%, P = 0.003), and comprised a higher proportion of EoE diagnoses made in the spring (Χ2 < 0.001). 43.3% of subjects with concurrent EoE and PFAS opted for treatment with elimination diet, and these measures failed to induce remission in 46.2% of cases. In most cases, elimination diet failed despite strict avoidance of PFAS trigger foods in addition to common EoE triggers including dairy, wheat, and eggs. EoE-PFAS was also associated with higher serum IgE at the time of EoE diagnosis (460.6 vs. 289.9, P < 0.019). Allergic rhinitis and a family history of food allergy were independently associated with having EoE-PFAS. The most common triggers of PFAS in adults with EoE are apples (21.1%), carrots (15.5%), and peaches (15.5%). Along with asthma, allergic rhinitis and atopic dermatitis, PFAS is a common allergic comorbidity that is highly associated with EoE. Further studies aimed at understanding mechanistic similarities and differences of PFAS and EoE may shed light on the pathogenesis of these closely related food allergy syndromes.

Food Allergy: What We Know Now

Food allergy is an adverse immune reaction that occurs reproducibly on exposure to a given food. Prevalence rates of food allergy continue to increase worldwide, sparking continual research efforts in finding a suitable and safe cure. Food avoidance, the current standard of care, can be difficult to achieve. This review aims to provide a broad overview of immunoglobulin E-mediated food allergy, highlighting its epidemiology, masqueraders, immunopathophysiology, clinical presentation, diagnostic work-up and available preventative and treatment strategies. This review also discusses novel, investigative therapies that offer promising therapeutic options, yet require continued research efforts to determine safety effects. Inducing tolerance, whether by immunotherapy or by the administration of monoclonal antibodies, allows us to move toward a cure for food allergy, which could vastly change this field of allergic diseases in the coming decades.

Position paper of the EAACI: food allergy due to immunological cross-reactions with common inhalant allergens

In older children, adolescents, and adults, a substantial part of all IgE-mediated food allergies is caused by cross-reacting allergenic structures shared by inhalants and foods. IgE stimulated by a cross-reactive inhalant allergen can result in diverse patterns of allergic reactions to various foods. Local, mild, or severe systemic reactions may occur already after the first consumption of a food containing a cross-reactive allergen. In clinical practice, clinically relevant sensitizations are elucidated by skin prick testing or by the determination of specific IgE in vitro. Component-resolved diagnosis may help to reach a diagnosis and may predict the risk of a systemic reaction. Allergy needs to be confirmed in cases of unclear history by oral challenge tests. The therapeutic potential of allergen immunotherapy with inhalant allergens in pollen-related food allergy is not clear, and more placebo-controlled studies are needed. As we are facing an increasing incidence of pollen allergies, a shift in sensitization patterns and changes in nutritional habits, and the occurrence of new, so far unknown allergies due to cross-reactions are expected.

Food allergies resulting from immunological cross-reactivity with inhalant allergens: Guidelines from the German Society for Allergology and Clinical Immunology (DGAKI), the German Dermatology Society (DDG), the Association of German Allergologists (AeDA) and the Society for Pediatric Allergology and Environmental Medicine (GPA)

A large proportion of immunoglobulin E (IgE)-mediated food allergies in older children, adolescents and adults are caused by cross-reactive allergenic structures. Primary sensitization is most commonly to inhalant allergens (e.g. Bet v 1, the major birch pollen allergen). IgE can be activated by various cross-reactive allergens and lead to a variety of clinical manifestations. In general, local and mild — in rare cases also severe and systemic — reactions occur directly after consumption of the food containing the cross-reactive allergen (e. g. plant-derived foods containing proteins of the Bet v 1 family). In clinical practice, sensitization to the primary responsible inhalant and/or food allergen can be detected by skin prick tests and/or in vitro detection of specific IgE. Component-based diagnostic methods can support clinical diagnosis. For individual allergens, these methods may be helpful to estimate the risk of systemic reactions. Confirmation of sensitization by oral provocation testing is important particulary in the case of unclear case history. New, as yet unrecognized allergens can also cause cross-reactions.

The therapeutic potential of specific immunotherapy (SIT) with inhalant allergens and their effect on pollen-associated food allergies is currently unclear: results vary and placebo-controlled trials will be necessary in the future. Pollen allergies are very common. Altogether allergic sensitization to pollen and cross-reactive food allergens are very common in our latitudes. The actual relevance has to be assessed on an individual basis using the clinical information.

Cite this as Worm M, Jappe U, Kleine-Tebbe J, Schäfer C, Reese I, Saloga J, Treudler R, Zuberbier T, Wassmann A, Fuchs T, Dölle S, Raithel M, Ballmer-Weber B, Niggemann B, Werfel T. Food allergies resulting from immunological cross-reactivity with inhalant allergens. Allergo J Int 2014; 23: 1–16 DOI 10.1007/s40629-014-0004-6

Anaphylaxis after accidental ingestion of kiwi fruit

Numerous cases of anaphylaxis after ingestion of kiwi fruit, after the skin tests and during oral immunotherapy were described. The article describes the case of severe anaphylactic reaction that occurred in a 55-year-old patient after accidental ingestion of kiwi. Allergy to kiwi fruit was confirmed by a native test with fresh kiwi fruit. After the test, the patient experienced generalized organ response in the form of headache, general weakness and rashes on the neck and breast, and dyspnea. The patient had significantly elevated levels of total IgE and IgE specific to kiwi fruit.

Release of mast cell tryptase into saliva: a tool to diagnose food allergy by a mucosal challenge test?

BACKGROUND

Our aim was to examine whether measurement of the saliva mast cell tryptase (MCT) concentrations before and after a mucosal challenge test with the offending food would be helpful in diagnosing food allergy.

METHODS

We performed a retrospective analysis of 44 food challenge tests performed in 38 patients between 2006 and 2009. Patients with a suspected history of food allergy chewed the food until they developed symptoms or until the amount of time known from the patients' history to usually be required for the provocation of symptoms had passed. In 5 patients, saliva samples for the measurement of MCT were collected at minutes 0, 1, 4, 8, 11, and 16 after the first onset of symptoms. The remainder of the patients only had samples taken before chewing and 4 min after the end of the test period.

RESULTS

During repeated measurements, MCT peaked about 4 min after the onset of symptoms (p = 0.028). During 33 of the 44 tests (75.0%), we observed oral symptoms during testing; after 25 of the 33 (75.8%) tests evoking symptoms, the saliva MCT concentration increased. The MCT increase was negative in all other tests where no oral symptoms could be provoked.

CONCLUSIONS

The measurement of saliva MCT 4 min after the onset of symptoms may be helpful to diagnose food allergy. Because of numerous confounding variables, however, a negative saliva MCT increase does not exclude food allergy.

Oral allergy syndrome: a clinical, diagnostic, and therapeutic challenge

OBJECTIVES

To provide a review of the literature and discuss the clinical, pathophysiologic, diagnostic, and therapeutic challenges of oral allergy syndrome (OAS).

DATA SOURCES

English-language publications on OAS (and pollen-food allergy syndrome) were identified through MEDLINE and through the reference lists of each identified article and review.

STUDY SELECTION

Articles pertaining to OAS with respect to its varied clinical presentation, underlying pathophysiology, available and investigational diagnostic testing, and evidence-based treatment options were selected.

RESULTS

OAS occurs in patients with a prior cross-reactive aeroallergen sensitization and clinically presents with initial oralpharyngeal symptoms after ingestion of a triggering fruit or vegetable. Although controversial, these symptoms may progress to systemic symptoms outside the gastrointestinal tract in 8.7% of patients and anaphylactic shock in 1.7%. OAS's underlying pathophysiology may play a role in clinical presentation and outcome, depending on whether the cross-reactive protein is a heat-labile PR-10 protein, a partially labile profilin, or a relatively heat-stable lipid transfer protein. Diagnostic testing is variable based on the underlying food tested, but fresh food skin prick test typically has the highest sensitivity. Treatment centers on avoidance and the consideration of self-injectable epinephrine. Because of its relationship with a cross-reactive aeroallergen sensitization, subcutaneous immunotherapy and sublingual immunotherapy have also been therapeutically tried with mixed results.

CONCLUSION

OAS is a challenging diagnosis to the practicing allergist because of its many clinical, diagnostic, and therapeutic considerations. Understanding these challenges and their underlying mechanisms can facilitate a knowledgeable approach to treating an oral allergy patient.

Food allergy overview in children

Food allergies have increased significantly in the past decade. An accurate history is crucial in approaching the management. At the outset, food intolerance must be distinguished from food allergies and, furthermore, these allergies should be classified into either an IgE, Non-IgE, or a mixed response. The clinical features vary from life-threatening anaphylaxis to milder IgE-mediated responses, atopic dermatitis, and gastrointestinal symptoms. The severity of the reaction and the potential risk for anaphylaxis on reexposure should be assessed. Milk, soy, egg, wheat, and peanut allergies are common in children, whereas peanut, tree nut, fish, shell fish allergies, and allergies to fruits and vegetables are common in adults. Structural proteins are important determinants of the severity of the reactions and may often predict the natural history and cross reactivity. Diagnostic work up must be guided by the clinical history. Skin testing and food-specific IgE done by standard methods are very useful, whereas oral challenges may be indicated in some situations. Majority of the patients outgrow their allergies to milk, soy, egg, and wheat, and some to peanut also, therefore, patients should be periodically reassessed. Novel diagnostic techniques which detect specific allergenic epitopes have been developed. Several newer therapies are promising.

An experimental and modeling-based approach to locate IgE epitopes of plant profilin allergens

BACKGROUND

Plant profilins are actin-binding proteins that form a well-known panallergen family responsible for cross-sensitization between plant foods and pollens. Melon profilin, Cuc m 2, is the major allergen of this fruit.

OBJECTIVE

We sought to map IgE epitopes on the 3-dimensional structure of Cuc m 2.

METHODS

IgE binding to synthetic peptides spanning the full Cuc m 2 amino acid sequence was assayed by using a serum pool and individual sera from 10 patients with melon allergy with significant specific IgE levels to this allergen. Three-dimensional modeling and potential epitope location were based on analysis of both solvent exposure and electrostatic properties of the Cuc m 2 surface.

RESULTS

Residues included in synthetic peptides that exerted the strongest IgE-binding capacity defined 2 major epitopes (E1, consisting of residues 66-75 and 81-93, and E2, consisting of residues 95-99 and 122-131) that partially overlapped with the actin-binding site of Cuc m 2. Two additional epitopes (E3, including residues 2-10, and E4, including residues 35-45) that should show weaker putative antigen-antibody associations and shared most residues with synthetic peptides with low IgE-binding capacity were predicted on theoretical grounds.

CONCLUSIONS

Strong and weak IgE epitopes have been uncovered in melon profilin, Cuc m 2.

CLINICAL IMPLICATIONS

The different types of IgE epitopes located in the 3-dimensional structure of melon profilin can constitute the molecular basis to explain the sensitization and cross-reactivity exhibited by this panallergen family.

Detection of Some Safe Plant-Derived Foods for LTP-Allergic Patients

BACKGROUND

Lipid transfer protein (LTP) is a widely cross-reacting plant pan-allergen. Adverse reactions to Rosaceae, tree nuts, peanut, beer, maize, mustard, asparagus, grapes, mulberry, cabbage, dates, orange, fig, kiwi, lupine, fennel, celery, tomato, eggplant, lettuce, chestnut and pineapple have been recorded.

OBJECTIVE

To detect vegetable foods to be regarded as safe for LTP-allergic patients.

METHODS

Tolerance/intolerance to a large spectrum of vegetable foods other than Rosaceae, tree nuts and peanut was assessed by interview in 49 subjects monosensitized to LTP and in three distinct groups of controls monosensitized to Bet v 1 (n = 24) or Bet v 2 (n = 18), or sensitized to both LTP and birch pollen (n = 16), all with a history of vegetable food allergy. Patients and controls underwent skin prick test (SPT) with a large spectrum of vegetable foods. The absence of IgE reactivity to foods that were negative in both clinical history and SPT was confirmed by immunoblot analysis and their clinical tolerance was finally assessed by open oral challenge (50 g per food).

RESULTS

All patients reported tolerance and showed negative SPT to carrot, potato, banana and melon; these foods scored positive in SPT and elicited clinical symptoms in a significant proportion of patients from all three control groups. All patients tolerated these four foods on oral challenge. Immunoblot analysis confirmed the lack of IgE reactivity to these foods by LTP-allergic patients.

CONCLUSION

Carrot, potato, banana and melon seem safe for LTP-allergic patients. This finding may be helpful for a better management of allergy to LTP.

Allergenic reactivity of the melon profilin Cuc m 2 and its identification as major allergen

BACKGROUND

Melon allergy is commonly associated with oral allergy syndrome (OAS) and with hypersensitivity to pollens and other plant foods. No melon allergen responsible for these clinical characteristics has yet been isolated, although profilin has been proposed as a potential target.

OBJECTIVE

To isolate natural and recombinant melon profilin, to evaluate its in vivo and in vitro reactivity, and to analyse its behaviour in simulated gastric fluid (SGF) and heat treatments.

METHODS

A pool or individual sera from 23 patients, and an additional group of 10 patients, all of them with melon allergy, were analysed by in vitro and in vivo tests, respectively. Natural melon profilin (nCuc m 2) and its recombinant counterpart (rCuc m 2) were isolated by poly-l-proline affinity chromatography, and characterized by N-terminal amino acid sequencing, matrix-assisted laser desorption/ionization analysis, DNA sequencing of cDNAs encoding rCuc m 2, and immunodetection with anti-profilin antibodies. In vitro analysis included IgE immunodetection, specific IgE determination, ELISA-inhibition assays, and histamine release (HR) tests. In vivo activity of nCuc m 2 was established by skin prick testing (SPT). The effect of SGF and heat treatment on rCuc m 2 was followed by immunodetection, ELISA inhibition, and HR assays.

RESULTS

Both purified forms of melon profilin were recognized by rabbit anti-profilin antibodies and IgE of sera from allergic patients, and showed molecular sizes typical of the profilin family. nCuc m 2 had a blocked N-terminus, whereas rCuc m 2 rendered the expected N-terminal amino acid sequence, its full protein sequence being highly similar (98--71% identity) to those of profilins from plant foods and pollens. The natural allergen displayed a slightly higher IgE-binding capacity than its recombinant counterpart. Specific IgE to nCuc m 2 and rCuc m 2 was found in 100% and 78% of the 23 individual sera analysed, respectively. nCuc m 2 evoked positive SPT responses in all (10/10) patients tested, and rCuc m 2 induced HR in two out of three sera assayed. SGF treatment readily inactivated rCuc m 2, as shown by its loss of recognition by anti-profilin antibodies, lack of IgE binding, and inability to induce HR. In contrast, heat treatment did not affect the IgE-binding capacity of rCuc m 2.

CONCLUSIONS

Profilin is highly prevalent in melon-allergic patients, and promptly inactivated by SGF, as expected for an allergen mainly linked to OAS.

Evaluation of food-pollen cross-reactivity by nose-mouth cross-challenge in pollinosis with oral allergy syndrome

BACKGROUND

Oral allergy syndrome (OAS) is often associated with pollen-induced rhinitis, and there are preferential associations between causative substances. If OAS and rhinitis are both immunoglobulin (Ig)E-mediated and there are cross-reacting proteins, it is expected that similar reactions can be elicited in the nose and mouth. In order to test this hypothesis we performed a series of 'cross-challenges' with foods and pollens in both the nose and the mouth.

METHODS

Nine patients with ascertained OAS due to vegetables and rhinitis due to pollens were studied. On the first day a nasal challenge with pollen extracts and an oral challenge with fresh food was carried out. After a week, washout nasal challenge with food and an oral challenge with pollens were performed. Immediate symptoms, mucosal tryptase and soluble eosinophil cationic protein (ECP) were assessed after each challenge.

RESULTS

The administration of pollen into the nose and food into the mouth elicited symptoms as expected, but the cross-challenge had no clinical effect. In parallel, tryptase and ECP increased after nasal challenge with pollens, whereas foods did not elicit a measurable response.

CONCLUSION

The cross-reactivity between foods and pollens, when evaluated at the shock organ, was not clinically evident. This data can be explained with a low concentration of cross-reagent epitopes in pollen extracts and food homogenized because of degradation. The different behaviour upon challenge suggests that different immunological mechanisms may act in the nose and mouth.

Food hypersensitivity in patients with seasonal rhinitis in Ankara

BACKGROUND

Food hypersensitivity (FH) affects 1-2 % of the adult population and is more common in atopic individuals. The aim of this study was to determine the frequency of FH and risk factors for its development in patients with seasonal rhinitis (SR) in our allergy clinic.

METHODS

We performed a retrospective study based on the medical records of 774 patients out of 955 patients diagnosed with SR in an adult allergy clinic between 1 January 1991 and 31 December 2003.

RESULTS

The mean age of the patients was 29.1 +/- 9.29 and 62.7 % were females. The most common major complaints were due to nasal symptoms in 82.3 %. The mean duration of SR was 6.8 +/- 6.8 years. Patients were symptomatic for a mean of 3.5 +/- 1.7 months per year. Skin prick tests (SPT) with common aeroallergens were positive in 685 patients (90.3 %), and the most common sensitivity was against timothy (85.1 %). The most common accompanying allergic disease was FH in 14 %. FH according to history and the results of SPT performed with food allergens were discordant. The most common clinical manifestations of FH were oral allergy (49.1 %) and cutaneous symptoms (38.9 %). Risk factors for the development of FH in patients with SR were dermatological symptoms, rhinitis duration > 5 years, symptom duration > 3 months per year, SPT reactivity to Artemisia vulgaris, tree pollen allergens (Corylus avellena, Betula verrucosa), and bee allergy.

CONCLUSION

FH was the most common (14 %) accompanying allergic disease in patients with SR. SPT with food allergens have limited diagnostic value for food allergy and/or intolerance. Risk factors for developing FH in patients with SR in Turkey were dermatological symptoms, duration of rhinitis > 5 years, duration of rhinitis symptoms > 3 months per year, and SPT reactivity to Corylus avellena.

Mustard allergy confirmed by double-blind placebo-controlled food challenges: clinical features and cross-reactivity with mugwort pollen and plant-derived foods

BACKGROUND

Mustard IgE-mediated allergy is supposed to be a rare cause of food allergy, and its clinical features and cross-reactivities have not been fully elucidated.

METHODS

A prospective study was carried out, recruiting mustard allergic patients, and paired control subjects. A clinical questionnaire was administered, and skin-prick tests (SPT) with panels of aeroallergens and foods, serum extraction for in vitro tests and double-blind placebo-controlled food challenges (DBPCFC) were performed.

RESULTS

Thirty-eight mainly adult patients, with 10.5% reporting systemic anaphylaxis, were included in the study [age (mean +/- SD): 21.9 +/- 8.6 years]. DBPCFC were performed in 24 patients, being positive in 14 cases (58.3%). Patients with positive outcome showed significantly greater mustard SPT than those with negative outcome (8.2 +/- 3.7 vs 5.3 +/- 2.4 mm, P <0.05), and the receiver-operating characteristic (ROC) curve analysis yielded a cut-off value for mustard commercial SPT of 8 mm, with a specificity of 90% (95% CI, 55.5-98.3), and a sensitivity of 50% (95% CI, 23.1-76.9). A significant association between mustard hypersensitivity and mugwort pollen sensitization was found (97.4% of patients), with partial cross-reactivity demonstrated by UniCAP System inhibition assays. All patients showed sensitization to other members of Brassicaceae family, and cross-reactivity among them was also confirmed. Moreover, significant associations with nut (97.4%), leguminous (94.7%), corn (78.9%), and Rosaceae fruit (89.5%) sensitizations were also shown. Around 40% of these food sensitizations were symptomatic, including food-dependent exercise-induced anaphylaxis in six patients.

CONCLUSIONS

Mustard allergy is a not-uncommon disorder that can induce severe reactions. Significant associations with mugwort pollinosis and several plant-derived food allergies are demonstrated, suggesting a new mustard-mugwort allergy syndrome. A relationship between this syndrome and food-dependent exercise-induced anaphylaxis is also reported.

Diagnosis and therapy of food allergy

According to the recently revised nomenclature for allergy the term "Food Hypersensitivity" is proposed to define a reaction on food exposure causing objectively reproducible symptoms or signs at a dose tolerated by normal subjects. Those reactions to food in which immunologic mechanisms are demonstrated comprise the term "Food Allergy". Immunologic reactions to food in which an immunoglobulin E (IgE)-mediated mechanism is established are defined as IgE-mediated food allergy. This review focuses on IgE-mediated allergic reactions to foods.

Allergy to kiwi

BACKGROUND

Allergy to kiwi fruit is being increasingly reported, but it has never been evaluated by means of a double-blind, placebo-controlled food challenge (DBPCFC) study.

OBJECTIVE

We sought to assess kiwi allergy on the basis of a DBPCFC and identify the patterns of allergen recognition in sensitized patients from a birch-free area.

METHODS

Forty-three patients with allergy symptoms who were sensitized to kiwi were evaluated by means of clinical history, skin tests, IgE determinations, and DBPCFCs. The pattern of allergen recognition was assessed by means of IgE immunoblotting. Sequence analysis of IgE-binding bands was performed by using Edman degradation.

RESULTS

DBPCFCs were performed in 33 patients; 4 patients had experienced severe anaphylaxis, and 6 patients declined informed consent. DBPCFC results were positive in 23 patients and negative in 10 patients. The most frequent clinical manifestation was oral allergy syndrome. Twenty-one percent of the patients were not allergic to pollen. Forty-six percent of patients experienced systemic symptoms, and this happened with higher frequency in patients not allergic to pollen (100%). Twenty-eight percent of the patients were sensitized to latex. The IgE-binding bands in kiwi extract more frequently recognized by patient sera were those of 30, 24, 66, and 12 kd, and they could not be associated with any pattern of kiwi-induced allergic reactions.

CONCLUSION

The results provide evidence that kiwi allergy is not a homogeneous disorder because several clinical subgroups can be established. No definite allergen-recognition pattern was associated with the type of allergic reactions to kiwi. One of 5 patients with kiwi allergy was not allergic to pollen, and these patients had the highest risk of systemic reactions to kiwi.

Kiwi fruit allergy: a review

Allergy to kiwi fruit was first described in 1981, and there have since been reports of the allergy presenting with a wide range of symptoms from localized oral allergy syndrome (OAS) to life-threatening anaphylaxis. The article reviews the available information concerning the clinical features of kiwi fruit allergy and the role of clinical investigations for diagnosis. Work identifying the major allergens in kiwi fruit has resulted in conflicting results, the possible reasons for which are discussed. The clinical associations of kiwi fruit allergy with allergies to pollens or latex are reviewed.

Clinical characteristics of melon (Cucumis melo) allergy

BACKGROUND

Although melon is a frequent allergy-eliciting fruit, allergic reactions to melon have rarely been reported.

OBJECTIVE

To evaluate and describe the clinical characteristics of melon allergy in melon-allergic patients.

MATERIALS AND METHODS

We evaluated patients allergic to melon and a control group of patients allergic to pollen. The diagnosis of melon allergy was based on a convincing clinical history, positive skin test results (prick-by-prick test), and positive results on oral challenge tests to melon.

RESULTS

A total of 161 patients were included in the study: 66 in the melon allergy group and 95 in the pollen control group. The melon allergy group included 35 female and 31 male patients with a mean age of 26.6 +/- 2.7 years (range, 5-61 years). Although all patients had oral symptoms, 13 (19.7%) of the patients had extraoral symptoms and none experienced generalized urticaria or anaphylaxis. Excluding other Cucurbitaceae fruits, peach, fig, and kiwi most frequently elicited positive skin test results and symptoms. Up to 23% of melon-allergic patients had a concomitant latex sensitization. Melon allergy was especially linked to pollen allergy, since all the melon-allergic patients were also allergic to pollen. Some differential features with respect to the pollen allergy control group were a higher prevalence of asthma (odds ratio [OR], 2.13; P < 0.05) and a statistical increase in the frequency of sensitization to several tree and weed pollens, including Ulmus (OR, 42.8) and Ambrosia (OR, 22.4).

CONCLUSION

The most important conditions linked to melon allergy are pollen allergy (100%), allergy to other nonrelated fruits, mainly peach (up to 62%), and latex sensitivity (up to 23%). Some differential features of the pollinosis in melon allergy were a higher prevalence of asthma and a higher frequency of sensitization to several weed and tree pollens.

Detection of clinical markers of sensitization to profilin in patients allergic to plant-derived foods

BACKGROUND

A proper classification of patients allergic to plant-derived foods is of pivotal importance because the clinical features of allergic reactions to fruits and vegetables depend on the nature and characteristics of proteins responsible for sensitization. However, in normal clinical settings this is presently impossible.

OBJECTIVE

We sought to detect clinical markers of sensitization to profilin.

METHODS

Seventy-one patients allergic to fruits and vegetables but not sensitized to lipid transfer protein or natural rubber latex were studied. Food allergy was ascertained on the basis of clinical history and positive skin prick test responses with fresh foods, commercial extracts, or both. Allergies to foods that had caused less than 2 adverse reactions were confirmed by means of open oral challenge. IgE reactivity to rBet v 1/rBet v 2 and to natural Phleum species profilin were detected. Moreover, IgE to the 30- to 40-kd and 60- to 90-kd birch pollen-enriched fractions, which also can be involved in cross-reactivity phenomena, were measured in sera from 52 patients by means of ELISA.

RESULTS

On the basis of in vitro tests, 24, 18, and 25 patients turned out to be sensitized to Bet v 1, Bet v 2, or both, respectively. Four patients had negative test results for both allergens. Hypersensitivity to Bet v 2 was strongly associated with clinical allergy to citrus fruits (39% in patients monosensitized to Bet v 2 vs 4% in patients monosensitized to Bet v 1, P <.025), melon or watermelon (67% vs 0%, P <.001), banana (66% vs 8%, P <.001), and tomato (33% vs 0%, P <.05), whereas Bet v 1 sensitivity was associated with clinical allergy to apple (100% vs 39%, P <.001) and hazelnut (56% vs 0%, P <.001). The sensitivity of a history of allergy to gourd fruits, citrus fruits, tomato, banana, or a combination thereof as a means to detect profilin-hypersensitive patients was 85% (41/48). The specificity of an allergy to any of these fruits exceeded 85%, with positive predictive values ranging between 68% and 91%.

CONCLUSION

In clinical settings in which laboratory investigations are not easily accessible, allergy to melon, watermelon, citrus fruits, tomato, and banana can be used as a marker of profilin hypersensitivity once a sensitization to natural rubber latex and lipid transfer protein is ruled out.

Occupational asthma due to freeze-dried raspberry

OBJECTIVE

To investigate the possibility that inhalation of raspberry powder at work can cause occupational asthma.

METHODS

We report the case of a 35-year-old, nonsmoking woman who complained of hay fever symptoms, wheezing, and shortness of breath two or three times a month exclusively in association with coating chewing gum with raspberry powder. Prick test extracts with the five types of fruit powder were produced. Peak expiratory flow rate monitoring five times daily was performed for an 8-week period while the patient was at work. Specific IgE and histamine release tests for raspberry powder were performed. Breathing zone dust measurements were taken.

RESULTS

Baseline lung function and histamine provocation test results were normal. During the 8-week monitoring period, 5 episodes of reduced peak expiratory flow rate were demonstrated. Each period was directly related to working with raspberry powder. A 9-mm prick test result positive for raspberry powder was seen (histamine control, 9 mm). In addition, the result of a radioallergosorbent test for raspberry was positive (0.84 kUA/L). The result of a histamine release test with raspberry powder from work was negative. Breathing zone total dust measurement was 5.9 mg/m3.

CONCLUSIONS

To our knowledge, this is the first description of occupational asthma due to the inhalation of raspberry powder. The symptoms of the patient described herein disappeared after she was moved to another part of the factory. Hygienic improvements were performed at the workplace to reduce the sensitization risk of other workers.

Profilin is a relevant melon allergen susceptible to pepsin digestion in patients with oral allergy syndrome

BACKGROUND

Melon allergy has been documented by means of double-blind, placebo-controlled food challenges. The most common clinical feature associated with melon allergy is oral allergy syndrome (OAS). However, no relevant allergens of melon have been identified to date.

OBJECTIVE

We sought to identify melon allergens and analyze their digestibility in human saliva and simulated gastric fluid (SGF) to provide a rationale for the OAS.

METHODS

Melon, zucchini, cucumber, and watermelon allergens were identified by means of IgE immunoblotting of sera from 21 patients with OAS after melon ingestion confirmed by means of double-blind, placebo-controlled food challenge. Further characterization was performed with rabbit antisera against sunflower pollen profilin and anticomplex glycans. Lability of allergens was assayed by incubation of melon extract in human saliva and SGF.

RESULTS

Several IgE-binding components between 15 and 60 kd and a main reactive band of 13 kd were detected in melon extract with the pooled sera from patients with melon allergy. As in melon, 13-kd components of zucchini, cucumber, and watermelon extracts were strongly recognized by the IgE antibodies of the patients with melon allergy and were identified as profilins. Putative cross-reacting carbohydrate determinants were also detected. Sera from 71% of patients recognized the melon profilin, and therefore profilin is considered a major allergen. Melon allergens were unaffected by crude human saliva. In contrast, most melon proteins, predominantly the 13-kd component (profilin), were quickly digested in the SGF.

CONCLUSION

In patients with OAS, a 13-kd protein identified as a profilin is a major melon allergen highly susceptible to pepsin digestion.

Reactivity to potential cross-reactive foods in fruit-allergic patients: implications for prescribing food avoidance

BACKGROUND

Prescribing therapeutic elimination diets in patients with fruit allergy should include recommendations on which other foods of the same family or group may be safely consumed. Evidence-based data on the management of fruit allergy are lacking; therefore, advice may vary from just avoiding the offending fruit, to overly restrictive diets of the entire botanical family. The aims of this investigation were to assess clinical reactivity to potential cross-reactive foods in fruit-allergic patients, and the implications for prescribing specific therapeutic elimination diets.

METHODS

Sixty-five adults diagnosed with clinical allergy to one or more fruits were evaluated for IgE-mediated allergy to other related foods, which might share cross-reactive antigens. Those with actual allergy to some Rosaceae fruit (including peach, apple, apricot, plum, and almond) underwent skin prick testing (SPT), food-specific IgE assessment by the Pharmacia CAP-FEIA system, and oral challenges with the entire group. For those with allergy to other fruits (chestnut, melon, banana, kiwi, or avocado) immunologic and clinical reactivity to all five were evaluated. Since a number of people in the study also had proven clinically allergy to some nut or legume (peanut, sunflower seed, walnut, pistachio, or hazelnut), the reactivity to the entire set was investigated.

RESULTS

Thirty-four of those tested (52%) were found to be clinically allergic to more than one fruit, so 125 allergic reactions occurred in the 65 patients. Peach, melon, kiwi, apple, and banana accounted for 72% of allergic reactions. Forty-two (65%) had sensitization to pollens, causing seasonal allergic rhinitis and/or asthma, and 18 (28%) were sensitized to latex. The 65 with IgE-mediated fruit allergy underwent 351 additional SPT and food-specific IgE determinations with potential cross-reactive foods considered in this study; 223 (64%) of these results were positive. The routine challenges with potential cross-reactive foods uncovered 18 further reactions in 14 (22%) out of 65 (to avocado in seven; apricot in three; plum in one; almond and peanut in one; banana and hazelnut in one; avocado, banana and kiwi in one). Only 8% (18/223) of positive results for SPT, or food-specific IgE levels of greater than 0.35 kU(A)/l to potential cross-reactive foods investigated in this study, were clinically relevant.

CONCLUSION

Elimination diets that rely on total group avoidance, or only on the results of allergy testing, might have resulted in unnecessary restriction of 205 foods in the 65 people studied. The lack of routine oral challenges with related fruits--before prescribing dietary restriction--may have allowed 18 food reactions in one-fifth (14/65) of patients to be overlooked.

Clinical features of cross-reactivity of food allergy caused by fruits

Fruits are increasingly recognized as a cause of food allergy. The wide cross-reactivity among these foods has been extensively studied. In this review we will focus on studies addressing the clinical relevance of cross-reactivity among fruits, the diagnostic management of patients complaining of reactions to multiple fruits, and adequate dietary recommendations.

Clinical implications of cross-reactive food allergens

As a consequence of the general increase in allergic sensitization, the prevalence of hypersensitivity reactions to multiple foods that share homologous proteins has become a significant clinical problem. A variety of these allergens conserved among plants (eg, profilin and lipid transfer proteins) and animals (eg, tropomyosin and caseins) have been characterized. Although studies with molecular biologic techniques have elucidated the nature of these ubiquitous allergens, clinical studies have lagged behind. The physician is called on to determine the risk of reaction to related foods among legumes, tree nuts, fish, shellfish, cereal grains, mammalian and avian food products, and a variety of other plant-derived foods that may share proteins with pollens, latex, and each other. Clinical evaluations require a careful history, laboratory evaluation, and in some cases oral food challenges. The pitfalls in the evaluation of food allergy-unreliable histories and limitations in laboratory assessment primarily caused by false-positive skin prick test responses/RAST results are magnified when dealing with cross-reactive proteins. This review focuses on the clinical data regarding cross-reacting food allergens with the goal of providing a background for improved risk assessment and a framework on which to approach these difficult clinical questions.