Pollen allergy in peach-allergic patients: sensitization and cross-reactivity to taxonomically unrelated pollens

Phenotypes and Endotypes of Peach Allergy: What Is New?

Peach allergy is emerging as a common type of fresh-fruit allergy in Europe, especially in the Mediterranean area. The clinical manifestations of peach allergy tend to have a peculiar geographical distribution and can range from mild oral symptoms to anaphylaxis, depending on the allergic sensitization profile. The peach allergen Pru p 7, also known as peamaclein, has recently been identified as a marker of peach allergy severity and as being responsible for peculiar clinical features in areas with high exposure to cypress pollen. This review addresses the latest findings on molecular allergens for the diagnosis of peach allergy, the clinical phenotypes and endotypes of peach allergy in adults and children, and management strategies, including immunotherapy, for peach allergy.

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.

Application of phage peptide display technology for the study of food allergen epitopes

Phage peptide display technology has been used to identify IgE-binding mimotopes (mimics of natural epitopes) that mimic conformational epitopes. This approach is effective in the characterization of those epitopes that are important for eliciting IgE-mediated allergic responses by food allergens and those that are responsible for cross-reactivity among allergenic food proteins. Application of this technology will increase our understanding of the mechanisms whereby food allergens elicit allergic reactions, will facilitate the discovery of diagnostic reagents and may lead to mimotope-based immunotherapy.

Influence of age on IgE response in peanut-allergic children and adolescents from the Mediterranean area

BACKGROUND

Peanut allergens are common triggers of food allergy. Analyses of sensitization patterns, relationships with other allergens, clinical symptoms, and variation with age are needed. We studied sensitization to Ara h 2, Ara h 9, and Pru p 3 in a peanut allergic children/adolescents and the relationship with peach and pollen.

METHODS

Peanut allergic patients aged between 1 and 20 years old were classified into two groups: A) allergic to peanut only and B) allergic to peach and peanut. The IgE response was measured to Ara h 2, Ara h 9, and Pru p 3.

RESULTS

Of 964 subjects evaluated, 28% were allergic to peanut. From this group, 68% were also sensitized to pollen. Urticaria was the most frequent entity followed by anaphylaxis and OAS. Fifty-eight percent had Ara h 2- and/or Ara h 9-specific IgE. More than half reported symptoms with peanut alone (Group A) and 35% to peanut and peach (Group B). We observed significant differences in sex, age, onset of symptoms, and sensitization to Artemisia between groups. IgE response to Ara h 2 was more frequent in Group A, and Ara h 9 and Pru p 3 in Group B. We observed a decrease in sensitization to Ara h 2 and an increase to Ara h 9 and Pru p 3 with increasing age.

CONCLUSION

Peanut allergy is frequent in subjects with allergy to plant foods, with Ara h 2 and Ara h 9 being two important allergens. In younger patients, Ara h 2 predominates over Ara h 9. The reverse was observed in older patients.

Correlation of anti-Pru p 3 IgE levels with severity of peach allergy reactions in children

BACKGROUND

Peach allergy is regarded as one of the most important fresh fruit allergies. Data are available on the state-of-the-art diagnosis, including food challenges, and a component-resolved diagnosis. However, the roles played by different peach allergens with respect to symptom severity are not completely understood.

OBJECTIVE

To evaluate the role of serum specific IgE to peach and recombinant allergens in the diagnosis of peach allergies in Italian children.

METHODS

Forty-four children with peach allergy confirmed by a placebo-controlled food challenge were divided into 2 groups based on their symptom severity: patients with mild oral allergy syndrome (OAS) and patients with systemic symptoms (SS). The presence of specific IgE to peach and rPru p 1, rPru p 3, and rPru p 4 was determined.

RESULTS

The presence of specific IgE to Pru p 4 and Pru p 1 was found significantly more frequently in patients with OAS, whereas specific IgE to Pru p 3 was not found significantly more frequently in patients with SS. Only anti-rPru p 4 IgE levels were significantly higher in patients with OAS, whereas no significant differences were found in anti-rPru p 1 and anti-rPru p 3 IgE levels between patients with OAS compared with patients with SS.

CONCLUSION

In Italian children with peach allergies, the presence of specific IgE to Pru p 3 is not associated with SS, and the levels of specific IgE to Pru p 3 do not correlate with the severity of the reactions.

Identification of european allergy patterns to the allergen families PR-10, LTP, and profilin from Rosaceae fruits

High fruit intakes are associated with significant health benefits but fruit allergy sufferers may be discouraged from eating fruit due to the symptoms they experience. Knowledge about allergens involved in fruit allergy and the frequent cross-reactions to other allergens is essential to (a) design the best strategy for fruit allergy testing (b) prescribe optimal avoidance diets, and (c) design technological solutions for development of hypoallergenic fruits. The objective of this review was to investigate whether some characteristic disease entities could be identified in Europe for allergy to Rosaceae fruits. Five allergy patterns were found involving the allergen families PR-10, LTP, and profilin. In the Western Mediterranean area allergies to Rosaceae fruits are caused by monosensitization to LTP, monosensitization to profilin, or co-sensitization to both these allergens. On the contrary, monosensitization to PR-10 and, to a lesser degree, co-sensitization to profilin and PR-10 is dominant in Northern and Central Europe. LTP sensitization is present both in pollinosis and non-pollinosis patients and is associated with peach allergy in particular. The disease pattern for patients sensitized to profilin is characterized by several concomitant allergies including grass and other pollens, Rosaceae and non-Rosaceae fruits. Finally, PR-10 sensitization is primarily associated to concomitant birch pollen and apple allergy.

Pru p 3-sensitised Italian peach-allergic patients are less likely to develop severe symptoms when also presenting IgE antibodies to Pru p 1 and Pru p 4

BACKGROUND

The roles played by different peach allergens with respect to symptom severity have not been completely ascertained. We have evaluated the diagnostic efficacy of peach recombinant allergens ImmunoCAP compared to peach in the identification of subjects at an increased risk for severe reactions to peaches.

METHODS

148 peach-allergic patients were divided based on their symptom severity into 2 groups: mild oral allergy syndrome (OAS) and severe OAS. Anti-rPru p 1, 3 and 4 IgE levels were measured. Statistical analyses were carried out using parametric and non-parametric tests.

RESULTS

anti-rPru p 1 and anti-rPru p 4 IgE levels were significantly higher in patients with mild OAS than in patients with severe OAS (p = 0.0001); in contrast, anti-rPru p 3 IgE levels were significantly higher in patients with severe OAS than in patients with mild OAS (p < 0.00005). Moreover, we found that any unitary increase in anti-rPru p 1 IgE values corresponded to a 2.48% reduction in the odds of having severe OAS (p = 0.048), whereas any unitary increase in anti-rPru p 3 IgE values corresponded to a 9.02% increase in the probability of having severe OAS (p = 0.001). Unexpectedly, we found that patients positive to rPru p 3 as well as rPru p 1 and 4 demonstrated a significant reduction of the odds of developing severe symptoms than those positive to rPru p 3 alone. Anti-rPru p 3 IgE levels were a significantly better indicator than anti-peach IgE values (p = 0.016) of patients with the highest risk for severe OAS. A cutoff of 2.69 kUA/l for anti-rPru p 3 IgE values better discriminated peach-allergic patients at a higher risk for symptoms.

CONCLUSIONS

Italian patients with positive anti-rPru p 1, 4 and 3 IgE levels seemed less likely to experience the clinical effects of high anti-rPru p 3 IgE values.

Purification and structural stability of the peach allergens Pru p 1 and Pru p 3

Pru p 1 (a Bet v 1 homologue) and Pru p 3 (a nonspecific lipid transfer protein; nsLTP) are major allergenic proteins in peach fruit, but differ in their abundance and stability. Pru p 1 has low abundance and is highly labile and was purified after expression as a recombinant protein in Escherichia coli. Pru p 3 is highly abundant in peach peel and was purified by conventional methods. The identities of the proteins were confirmed by sequence analysis and their masses determined by MS analysis. The purified proteins reacted with antisera against related allergens from other species: Pru p 1 with antiserum to Bet v 1 and Pru p 3 with antiserum to Mal d 3 (from apple). The presence of secondary and tertiary structure was demonstrated by circular dichroism (CD) and high field NMR spectroscopy. CD spectroscopy also showed that the two proteins differed in their stability at pH 3 and in their ability to refold after heating to 95 degrees C. Thus, Pru p 1 was unfolded at pH 3 even at 25 degrees C but was able to refold after heating to 95 degrees C at pH 7.5. In contrast, Pru p 3 was unable to refold after heating under neutral conditions but readily refolded after heating at pH 3.

Peach ( Prunus persica L. Batsch) allergen-encoding genes are developmentally regulated and affected by fruit load and light radiation

The fruits of Rosaceae species may frequently induce allergic reactions in both adults and children, especially in the Mediterranean area. In peach, true allergens and cross-reactive proteins may cause hypersensitive reactions involving a wide diversity of symptoms. Three known classes of allergenic proteins, namely, Pru p 1, Pru p 3, and Pru p 4, have been reported to be mostly involved, but an exhaustive survey of the proteins determining the overall allergenic potential, their biological functions, and the factors affecting the expression of the related genes is still missing. In the present study, the expression profiles of some selected genes encoding peach allergen isoforms were studied during fruit growth and development and upon different fruit load and light radiation regimens. The results indicate that the majority of allergen-encoding genes are expressed at their maximum during the ripening stage, therefore representing a potential risk for peach consumers. Nevertheless, enhancing the light radiation and decreasing the fruit load achieved a reduction of the transcription rate of most genes and a possible decrease of the overall allergenic potential at harvest. According to these data, new growing practices could be set up to obtain hypoallergenic peach fruits and eventually combined with the cultivation of hypoallergenic genotypes to obtain a significant reduction of the allergenic potential.

T-cell epitopes of the major peach allergen, Pru p 3: Identification and differential T-cell response of peach-allergic and non-allergic subjects

Lipid transfer proteins (LTPs), particularly peach Pru p 3, are the most relevant plant food allergens in the South of Europe, and, therefore, their allergic properties have been extensively studied. However, neither T-cell epitopes nor their effect on the patients' T-cell response has been investigated in any member of the LTP panallergen family. The objective of the present study was to map the major T-cell epitopes of Pru p 3, as well as to evaluate their induced T-cell response in peach-allergic versus control subjects. Thus, peripheral blood mononuclear cells (PBMCs) from 18 peach-allergic patients and Pru p 3-specific T-cell lines (TCLs) from 9 of them were cultured with Pru p 3 and with a panel of 17 derived peptides (10-mer overlapping in 5 amino acids representing the full sequence of Pru p 3). Proliferation in 5-day assays was carried out via tritiated-thymidine incorporation, while IL4 and IFNgamma production was assessed via sandwich enzyme-linked immunosorbent tests (ELISA) of TCL culture supernatants. The results were compared to those obtained from 10 non-peach allergic control volunteers. Two consecutive peptides showed the highest activation capacity. About 74% of PBMCs and TCLs recognized them, forming a single T-epitope: Pru p 3(65-80). Additionally, other specific T-cell epitopes were observed. Pru p 3(25-35) was detected by more than 60% of TCLs from peach-allergic patients, and Pru p 3(45-55) only activated PBMCs from control subjects. Interestingly, TCLs from patients were associated with a Th2-type, whereas control TCLs presented a Th1-type cytokine response. The major immunogenic T-cell epitope identified in Pru p 3, Pru p 3(65-80), is a good candidate to develop new vaccines for hypersensitivity reactions associated with LTP allergens from Rosaceae fruits.

A hypoallergenic vaccine obtained by tail-to-head restructuring of timothy grass pollen profilin, Phl p 12, for the treatment of cross-sensitization to profilin

Profilins are highly cross-reactive allergens in pollens and plant food. In a paradigmatic approach, the cDNA coding for timothy grass pollen profilin, Phl p 12, was used as a template to develop a new strategy for engineering an allergy vaccine with low IgE reactivity. Non-IgE-reactive fragments of Phl p 12 were identified by synthetic peptide chemistry and restructured (rs) as a new molecule, Phl p 12-rs. It comprised the C terminus of Phl p 12 at its N terminus and the Phl p 12 N terminus at its C terminus. Phl p 12-rs was expressed in Escherichia coli and purified to homogeneity. Determination of secondary structure by circular dichroism indicated that the restructuring process had reduced the IgE-reactive alpha-helical contents of the protein but retained its beta-sheet conformation. Phl p 12-rs exhibited reduced IgE binding capacity and allergenic activity but preserved T cell reactivity in allergic patients. IgG Abs induced by immunization of mice and rabbits with Phl p 12-rs cross-reacted with pollen and food-derived profilins. Recombinant Phl p 12-rs, rPhl p 12-rs, induced less reaginic IgE to the wild-type allergen than rPhl p 12. However, the rPhl p 12-rs-induced IgGs inhibited allergic patients' IgE Ab binding to profilins to a similar degree as those induced by immunization with the wild type. Phl p 12-rs specific IgG inhibited profilin-induced basophil degranulation. In conclusion, a restructured recombinant vaccine was developed for the treatment of profilin-allergic patients. The strategy of tail-to-head reassembly of hypoallergenic allergen fragments within one molecule represents a generally applicable strategy for the generation of allergy vaccines.

Molecular and immunological characterization of cytochrome c: a potential cross-reactive allergen in fungi and grasses

BACKGROUND

Recombinant allergens are required for component-resolved diagnosis/therapy of allergic disorders. The study was aimed to express and characterize an allergenic protein from Curvularia lunata and study its cross-reactivity.

METHODS

A clone encoding a 12-kDa protein screened from the cDNA library of C. lunata was sequenced and expressed in pET22b+ vector. The purified protein was characterized by biophysical and immunological methods.

RESULTS

The sequence of gene encoding a 12-kDa protein showed homology to cytochrome c. It was expressed in Escherichia coli yielding 0.5 mg protein/l culture and designated as Cur l 3. The absorption and circular dichroism spectrum of Cur l 3 were similar to horse cytochrome c and the protein reacted with cytochrome c antibody. ELISA with different fungal-positive patients' sera showed > or = 3 times specific IgE to Cur l 3 compared with healthy controls. Mice anti-Cur l 3 reacted with tropical and temperate grass extracts. Protein also reacted with grass-positive patients' sera. In vitro stimulation of peripheral blood mononuclear cells from C. lunata, fungi or grass-positive patients with it released significant levels of Th2 cytokines. In vivo testing of this protein in allergic patients showed marked positive skin reactivity in 60% fungal and 43% grass-positive cases. Cross inhibition assays (EC(50)) demonstrated allergenic cross-reactivity of Cur l 3 with fungi and grasses.

CONCLUSIONS

Cytochrome c, a major allergen from C. lunata was cloned, sequenced and expressed. It was identified as a cross-reactive allergen among fungi and grasses and has potential for clinical application.

Description of a novel panallergen of cross-reactivity between moulds and foods

The present investigation is undertaken to demonstrate a novel cross-reactivity between aeroallergens (moulds fungi imperfecti) and allergens from foods (spinach and mushroom Agaricus bisporus). We have performed a dual study in vivo and in vitro, in a population of atopic patients. Data from in vivo tests performed with spinach and mushroom have been statistically analysed. To the in vitro assays, mushroom and spinach extracts have been obtained, and sera from moulds allergic patients analysed by means of IgE-immunoblott assays. Inhibition experiments have been also performed to study a possible relation between proteins. Statistical analysis of data showed a relation between allergenicity to moulds (Alternaria alternata, Cladosporium herbarum and/or Aspergillus fumigatus), and positive skin prick tests with mushroom and/or spinach. The immunoblotts performed showed that seven moulds allergic patients had a strong recognition of a protein with a molecular weight of about 30 kD present both in spinach and mushroom extracts, and by means of inhibition assays we could determine that these two proteins were related. This study demonstrates the existence of a new allergen responsible for cross reactivity between moulds and two frequently consumed foods, mushroom and spinach. We conclude that a novel cross-reactive allergen between aeroallergens and foods has been identified.

Antibody profiles and self-reported symptoms to pollen-related food allergens in grass pollen-allergic patients from northern Europe

BACKGROUND

Most studies on pollen-related food allergy have so far focused on the association of birch/weed pollen allergens and plant food allergy. The aim of this study was to elucidate the allergen spectrum among a group of grass pollen-allergic patients from northern Europe and to relate the results to clinical histories of pollen-related food allergy.

METHODS

Fifty-eight grass pollen-allergic patients answered a questionnaire regarding allergy to foods. Blood samples were taken to test IgE-reactivity to a large panel of pollen allergens and pollen- and nonpollen-related food allergens using crude allergen extracts and recombinant and native allergens.

RESULTS

Three different groups of grass pollen-allergic patients were identified according to their IgE antibody profile: a grass pollen group only (19%), a grass and tree pollen group (29%) and a grass, tree and compositae (pan-) pollen group (48%). No sensitization to Bet v 1 as well as almost no IgE to plant food was observed in the grass pollen group. In contrast, nearly all patients in the two tree-related groups had IgE to Bet v 1, which reflected the high frequency of adverse reactions to typical birch-related food in these groups. Only four patients belonging to the pan-pollen group displayed IgE to profilin Phl p 12/Bet v 2. Patients in the pan-pollen group reported significantly more symptoms to food allergens compared with patients in the two other groups. The most frequently reported symptom was the oral allergy syndrome.

CONCLUSIONS

Sensitization to grass pollen alone is rare among grass pollen-allergic patients from northern Europe. The majority of patients are in addition sensitized to birch (Bet v 1), which seems to be closely related to their pollen-derived food allergy. The study highlights the advantage of using well-defined allergen molecules for the diagnosis of cross-reactivity between pollen and food allergens.

Food hypersensitivity in Portuguese adults

OBJECTIVE

To describe the frequency and epidemiological features of self-reported food hypersensitivity in Portuguese adults.

DESIGN

Cross-sectional.

SETTING

Participants were selected by random digit dialing among residents of Porto.

SUBJECTS

In total, 659 individuals over 39 y were asked to recall the occurrence of food hypersensitivity, and to describe the most serious episode. The adoption of eviction diets and previous medical diagnosis of food allergy were recorded, and recent dietary intake was evaluated using a validated food frequency questionnaire.

RESULTS

Self-reported food allergy was more frequent in women than men (7.3 vs 1.9%, P<0.01) and decreased with age. Age- and sex-standardized (European population > or =40 y) prevalence of food hypersensitivity was 4.8% (95% CI 3.4-6.9%). Most subjects (67.6%) referred allergy to a single food, fresh fruits being the more frequently incriminated (25%). Approximately 90% that reported food allergy declared the adoption of eviction diets, although 53% in fact ingested the incriminated foods during the previous year.

CONCLUSIONS

The adult prevalence of food hypersensitivity in Porto is one of the lowest observed worldwide, probably reflecting specificities of the genetic make-up and dietary patterns of our population.

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.

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.

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.

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.

Clinical cross-reactivity among foods of the Rosaceae family

BACKGROUND

Foods from the Rosaceae botanical family have been increasingly reported as causes of allergic reaction. Patients frequently have positive skin tests or radioallergosorbent test results for multiple members of this botanical family.

OBJECTIVE

Our purpose was to investigate the clinical cross-reactivity assessed by double-blind, placebo-controlled food challenge (DBPCFC) of Rosaceae foods (apricot, almond, plum, strawberry, apple, peach, and pear).

METHODS

Thirty-four consecutive adult patients complaining of adverse reactions to Rosaceae were included in the study. Skin prick tests and CAP System (FEIA) were performed with Rosaceae foods in all patients. Clinical reactivity to Rosaceae was systematically evaluated by open food challenges (OFCs), unless there was a convincing history of a recent severe anaphylaxis. Positive reactions on OFCs were subsequently evaluated by DBPCFCs.

RESULTS

Twenty-six and 24 patients had positive skin prick tests and CAP FEIA with Rosaceae, respectively; from these 88% and 100% had positive tests with >/=2. No evidence of clinical reactivity was found in 66% percent of positive skin prick tests and 63% of positive specific IgE determinations to fruits. A total of 226 food challenges (including OFC and DBPCFC) were performed in the 28 patients with positive skin prick tests or CAP System FEIA. Of 182 initial OFCs carried out, 26 (14%) reactions were confirmed by DBPCFCs. Overall, 40 reactions were considered positive in 22 patients with positive skin tests or CAP FEIA. Thirty-eight reactions had been previously reported, the remaining two were detected by systematic challenges. Most reactions were caused by peach (22 patients), apple (6), and apricot (5). Ten patients (46%) were clinically allergic to peach and other Rosaceae.

CONCLUSION

Positive skin test and CAP System FEIA should not be taken as the only guide for multi-species dietary restrictions. Nevertheless, the potential clinical allergy to other Rosaceae should not be neglected. If the reported reaction is confirmed, current tolerance to other Rosaceae should be precisely established unless there has been ingestion without symptoms after the reaction.