|Year : 2015 | Volume
| Issue : 1 | Page : 24-27
Sensitization to plant food allergens in patients with asthma
Mozhgan Moghtaderi1, Shirin Farjadian1, Irma Reihani2
1 Department of Immunology, Allergy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
2 Devision of Allergy, Allergy Clinic of Shooshtari, Shiraz University of Medical Sciences, Shiraz, Iran
|Date of Web Publication||17-Aug-2015|
Department of Immunology, Allergy Research Center, Shiraz University of Medical Sciences, Shiraz
Source of Support: None, Conflict of Interest: None
Purpose: Hypersensitivity to fruits and vegetables is assumed to play a role in the etiology and deteriorating of asthma symptoms in some patients, little is known about allergy to some fruits and vegetables in patients with asthma. The purpose of this study was to identify probable sensitization to eggplant, Shiraz grape, melon, and mango in patients with asthma. Materials and Methods: The study included 50 patients with moderate to severe persistent asthma and 50 healthy individuals with no history of asthma and atopic diseases. Skin tests were performed in both patient and control group with fresh eggplant, Shiraz grape, melon, and mango as well as the commercial extracts of mango and melon. Results: Among patients with asthma, the most frequent positive skin tests were to eggplant (48%), fresh melon (30%) and extracts of melon and mango (18% for each) which all were significantly different from the control group. Skin sensitization to Shiraz grape and fresh mango showed no difference to control group. Skin tests of 21 patients (42%) were negative to the all tested allergens. Conclusion: Forty percent of our patients had clinical symptoms to eggplant and more than half of those revealed positive skin tests to a fresh extract of this plant.
Keywords: Asthma, eggplants, grape, mango, melon, skin test
|How to cite this article:|
Moghtaderi M, Farjadian S, Reihani I. Sensitization to plant food allergens in patients with asthma. Indian J Allergy Asthma Immunol 2015;29:24-7
|How to cite this URL:|
Moghtaderi M, Farjadian S, Reihani I. Sensitization to plant food allergens in patients with asthma. Indian J Allergy Asthma Immunol [serial online] 2015 [cited 2020 Jan 27];29:24-7. Available from: http://www.ijaai.in/text.asp?2015/29/1/24/162975
| Introduction|| |
Asthma is an inflammatory condition in response to inhaled or ingested allergens. There are controversies about the role of diet on incidence or worsening the clinical symptoms in these patients. ,
Eggplant (Solanum melongena) is widely used in Asian countries. Clinical allergic symptoms to eggplant are reported as anaphylaxis, urticaria, and oral allergy syndrome. Allergic reaction to eggplant is attributed to cross-reactivity with tomato and grass pollen. ,,
Shiraz grape (Vitis vinifera) is a dark-skinned grape that historically cultivated around Shiraz, Iran. Today, Shiraz grape is grown throughout the world. Patients with grape allergy present life-threatening anaphylaxis, oral allergy syndrome or asthma. Allergy to the grape is reported to be associated with allergy to pollen, other fruits, and latex. ,
Melon (Cucumis melo) is one of the most common fruits leads to allergic reactions. It is originated from Asia or Africa.  Patients with melon allergy experienced oral and extraoral symptoms. There is a high frequency of cross-reactivity between melon and some weeds or pollens. 
Mango (Mangifera indica) is usually eaten as fresh fruit. The immediate reactions to mango may present as anaphylaxis, angioedema, urticaria, wheezing, and dyspnea. Mango antigens have cross-reactivity with pollen, banana, tomato, celery, and nuts. ,,
The primary test for the diagnosis of IgE-mediated food allergy is a skin prick test (SPT) in which a drop of the certain food commercial extract is introduced into the dermis. Due to enzymatic degradation of food proteins through isolation, fresh food extracts are preferentially used in skin testing that is called prick-prick test (PPT).
A great number of patients with asthma describe clinical allergic symptoms after ingestion of some vegetables and fruits. This study was designed to investigate how much eggplant, Shiraz grape, melon, and mango may elicit positive skin test and allergic symptoms in patients with asthma.
| Materials and methods|| |
During a 6 months period, from June to November 2012, this cross-sectional study was performed on 50 adult patients with asthma who were referred to an allergy clinic at Shooshtari Hospital affiliated to Shiraz University of Medical Sciences, Iran. All the patients were diagnosed with moderate to severe persistent asthma according to the Expert Panel Report 3.  Patients who were under treatment with systemic corticosteroids, angiotensin-converting-enzyme inhibitor or beta-blocker agents were excluded from the study. Fifty unrelated healthy individuals with no personal or family history of asthma and other atopic diseases were selected by simple random sampling as a control group of the same ethnicity and from the same geographic region. After approval of the study, protocol by Ethics Committee of Shiraz University of Medical Sciences, informed consent was obtained from each participant in both groups.
Allergic reactions including oral allergy syndrome, respiratory symptoms and rhinitis following the ingestion of eggplant, Shiraz grape, melon, and mango were asked from patients by a questionnaire. Tingling and burning sensation in the mouth with or without swelling within a few minutes after ingestion was considered oral allergy syndrome. Cough, dyspnea, and wheeze were considered respiratory symptoms and sneezing and rhinorrhea were considered allergic rhinitis.
SPT were performed on the forearms using standard commercial extracts of melon and mango (Stallergenes, Antony, France). Sensitization to fresh extracts of melon, mango, raw eggplant and Shiraz grape was also evaluated by PPTs in which the culprits were pricked with a sterile lancet and then pricked into the skin with the same lancet. Histamine (10 mg/mL) and saline were used as positive and negative controls, respectively. The results of the skin tests were examined after 15 min and considered positive when the wheal was 3 mm greater in diameter than the negative control. Topical corticosteroids were stopped 1-day before the skin test.
Statistical analysis was carried out with the Chi-square or Fisher exact tests by Epi Info version 6 (Chicago, USA) and P < 0.05 were considered statistically significant.
| Results|| |
Fifty patients with moderate to severe persistent asthma (39 women, 11 men), aged 12-62 years (mean age 32 ± 11.8) and fifty healthy individuals (38 women, 12 men), aged 16-70 years (mean age 35 ± 11.4) were included in the study. The results of positive SPT to eggplant, Shiraz grape, melon and mongo in comparison with control group are shown in [Table 1]. Twenty-one patients (42%) with asthma were negative for all of the six tested allergens.
Based on questionnaire evaluation, 34 patients (68%) pointed to clinical allergy symptoms to eggplant. The most frequent symptoms were nasal irritation in 30 patients (60%), an oral allergy syndrome in 23 patients (46%) and respiratory manifestations in 19 patients (38%). In 59% of these patients, allergy to eggplant was confirmed by positive PPT. Four patients with positive skin test to eggplant reported no history of clinical symptoms to this plant.
Twenty-one patients (42%) stated a history of clinical symptoms to Shiraz grape, but only three of them showed positive skin test to fresh grape whereas, two patients with positive skin test to grape who had no history of clinical symptoms. The most frequent symptoms to grape were nasal irritation in 20 (40%), an oral allergy syndrome in 14 (28%) and respiratory manifestations in 13 (26%).
|Table 1: The number of patients with asthma and healthy controls with positive SPTs|
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Clinical reactivity to melon was explained by 40 patients (80%) while 14 of them showed a positive reaction to fresh melon and nine of them had positive skin tests to a commercial extract of melon. All patients with a positive reaction to commercial extract showed a positive reaction to fresh melon also. Only one patient with positive skin test to melon had no history of clinical symptom. The most frequent symptoms to melon were nasal irritation in 34 (68%), an oral allergy syndrome in 26 (52%) and respiratory manifestations in 23 (46%).
Eighteen patients (36%) had a history of clinical symptom after ingestion of mango while only seven of those showed positive skin test to fresh mango and eight of them had a positive reaction to a commercial extract of mango. Two patients with positive PPTs and one with positive SPT to mango had no history of clinical symptom to this fruit. The most common symptoms were nasal irritation (30%) oral allergy syndrome (30%) and respiratory symptoms (24%).
| Discussion|| |
The role of fruits and vegetables in developing asthma is still doubtful. In our study, we found positive skin sensitization accompanied with allergic symptoms to eggplant in 40% of our patients with asthma which might be due to the high contents of histamine and serotonin in eggplant.  Among our patients with clinical symptoms to eggplant, just 59% showed positive PPT. False-negative skin tests might be caused by the low potency of the prepared extract, weak puncture, concurrent parasitic infections, reduced reactivity of skin in elderly patients, and nonIgE-mediated mechanisms.  Evaluation of serum specific IgE levels against eggplant allergens can be practical to clear true IgE-mediated responses to this plant. Four of our patients showed positive PPT to eggplant with no history of clinical symptom to that. The false positive test can be induced by nonspecific mast cell secretagogues or irritants in the eggplant or after infection with the respiratory syncytial virus.  A positive skin test is not enough to confirm the presence of allergic disease, however; it shows allergic sensitization which may predict the subsequent onset of allergic symptoms.  Seven individuals in the control group showed a positive reaction to eggplant. They reported no history of clinical symptom to this plant. The amount of histamine in eggplant accounted to be enough to provoke positive skin test even in few nonatopic persons. 
Immediate hypersensitivity reaction to eggplant appeared in our patients as nasal irritation, respiratory manifestations, and oral allergy syndrome. Specific IgE cross-linking by eggplant allergens leads to mast cell degranulation and releasing of histamine and other mediators which is followed by bronchoconstriction, vasodilation in the nose and oral allergy symptoms. 
The results of this study showed no remarkable correlation between positive PPT to Shiraz grape in patients with asthma. Two patients with positive skin tests to grape had no history of clinical symptoms. Cross-reactivity with other allergens may elicit positive skin test in individuals with no clinical symptoms. 
Among the plants studied here, clinical symptoms to melon were frequent by history (80%). The comparison of PPT and SPT results to melon showed more positivity to PPT. Enzymatic degradation of proteins during the extraction of food allergens should also be considered  and because of this fault, PPT is preferred. Along with 40 patients with a history of clinical symptoms to melon, 14 patients showed positive PPT. This figure is almost similar to that reported from Mashhad (Eastern Iran). 
Mango is not originally cultivated in Iran and just distributed in some part of the country. The results of PPT showed no significant difference between patients and controls. We did not observe any positive skin reaction to the commercial extract of mango in the control group whereas 18% of the patients had positive PPT. It appears that enzymatic degradation of proteins in mango extract is lower than other food extracts.
| Conclusion|| |
Forty percent of the patients with asthma had clinical symptoms to eggplant which in more than half of them an allergic reaction to eggplant was confirmed by PPT.
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Conflicts of interest
There are no conflicts of interest.
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