A PROSPECTIVE STUDY OF MUSTARDALLERGY IN ALLERGIC RHINITIS CASES
DM Tripathi, Suman Kumar**, Ashok Gupta***, Neena Mehta***
*Hon. Allergologist, Bombay Hospital Institute of Medical Sciences, Mumbai - 20. **ENT Surgeon, ENT and Allergy Centre, Panchkula, Haryana. ***Head, Pharmacy Dept. Govt. Polytechnic for women, Chandigarh. ****Dept. of Biochemistry, Post Graduate Institute for Medical Sciences, Chandigarh.
Seventy eight consecutive patients suffering from allergic rhinitis enrolled in this study. Modified skin prick test for different aeroallergens along with food allergens were carried out. Majority of patients showed strongly positive skin reaction to mustard (74%). Among other aeroallergens 73% patients were sensitive to house dust followed by house dust mite Dermatophagoides farnae. Cutaneous sensitivity to Parthenium hysterophorus allergen was as high as 70%. However, seventy eight per cent patients showed strong sensitivity to pollen extract of Brassica species.
Patients who showed positive reaction to mustard were selected for avoidance measures. Complete avoidance of mustard in diet in allergic rhinitis cases having positive medical history and cutaneous sensitivity to mustard allergen extract showed considerable symptomatic relief in approximately 60% patients.
Prevalence of food allergy occurs in approximately 8-10% of the general population. It varies with dietary pattern of the people. A true food allergy is a disorder in which ingestion of a small amount of food elicit an abnormal immunologically mediated clinical response. Food may cause allergic reaction by several mechanisms. The classic type IgE mediated reaction is the most thoroughly studied and potentially important in view of the risk of the life threatening reactions in some people.
A carefully taken history is the first step in identifying the presence of food allergy. Although, patients may indicate history of food allergy, it is important to recognize that very often food allergy is unsuspected, and manifestations of the patients complaints may masquerade as those of another disorder. It is therefore imperative that the clinician maintain a high index of suspicion of food allergy particularly when any of the shock organs are involved. 
In India, the consumption of mustard in one or the other form is very high, particularly in northern parts of the country. Mustard plant belongs to the family Brassicaceae and two species e.g. Brassica nigra and Brassica juncea are extensively cultivated. Mustard powder is used as spice and mustard oil is used for cooking purposes.
This study was aimed to assess the clinical significance of mustard allergy and its correlation with allergy due to pollen of mustard plant in allergic rhinitis.
MATERIAL AND METHODS
The diagnosis and treatment of immediate hypersensitivity reactions to foods is directed towards the identification and removal of offending foods. The use of immediate hypersensitivity skin testing as a diagnostic tool in clinical allergy dates to the study on hay fever by Blacley in the 1960ís. Since that time it has become the standard clinical method for demonstrating the presence of allergen specific antibodies in sensitive individuals. 
From December, 1998 to December, 2000 78 consecutive patients with positive history of allergic rhinitis were included in this study. Responders were interviewed and a questionnaire was administered to determine the presence or absence of a personal or immediate family history to atopic disease. Based on the results of this questionnaire skin test was performed using modified prick test method.  Allergen extract used for skin prick testing were standardized on protein nitrogen units and biological activity units based on histamine equivalent prick test. Apart from food allergens, other inhalant allergens such as pollen, dust, dust mite and mould allergens were also tested to observe the cross reactivity.
Fresh extracts of mustard seed powder of Brassica nigra and Brassica juncea were subjected to skin prick testing as suggested by Bindeslev-Jensen.  A drop of liquid food was placed on the forearm and pricked through. The prick testing was also performed with fresh extract of mustard seed powder standardized by w/v method (1:10 concentration) as advised by Rance et al. 
The volar side of the forearm cleaned with isopropyl alcohol. The skin was marked with a ball point so as to identify and locate the site of each test. A single drop of each test solution was placed with help of the applicator. A sterile lancet was then placed through the drop of an allergen extract at acute angle to the skin and a shallow lift was made. The lancet was raised for a second before the skin was released. This was repeated for each drop of allergen solution. The lancet was carefully wiped on dry cotton or wool between the tests.
After the skin test was performed, drop of allergen extract was wiped after 15 minutes. The results were assessed by relating wheal area to that induced by histamine at 0.1% base. We excluded a dermographic reaction by using a negative control, 50% glycerosaline solution. Histamine (positive control) reactions were read after 10 minutes. The other test reactions were read after 15 to 20 minutes. Wheal and flare reactions were carefully out lined with a fine porous tipped and tape transferred on to a paper for a permanent record. The size of wheal and flare reactions were recorded in millimeters with the mean of the largest and midpoint orthogonal diameters. Only wheals half the average of the positive control or more, and equal to or larger than 3 mm were scored as positive. Although wheal and erythema reactions of different sizes were also recorded.
Seventy eight patients were subjected to skin testing procedures after taking careful medical history. None of these subjects experienced a systemic reactions associated with testing. Majority of patients who were subjected to skin prick testing showed strong sensitivity to mustard allergen extract (78%), followed by pollen extract of mustard family (74%). Bengal gram (chana) showed 66% reactivity (Table 1). Other food allergens tested did not show significant reactions.
TABLE 1 :
Cutaneous sensitivity to food allergens
No. of patients
Bengal gram (chana)
Other aeroallergens which showed strongly positive reactions in selected patients belonged to house dust (73.1%), house dust mite Dermatophagoides farinae (65.4%).
Among pollen allergens, patients showed high skin reactivity to Parthenium hysterophorus followed by grass pollen (Cynodon, Zea mays, etc.) Table 2. However, maximum skin reactivity was observed with pollen extract of Brassica species (mustard pollen) as high as 78.20%.
We observed significant crossreactivity among pollen extract of mustard plant and mustard (seed) powdered extract. Patients who showed skin sensitivity to pollen extract and mustard powder extract, were also found having cutaneous sensitivity to fresh extract of mustard powder.
Although mustard allergy is not well recognized, this study will throw some light on its significance in northern part of the country as mustard is extensively consumed as spice and its oil for cooking purpose. High degree of skin reactivity was observed with mustard extract (78%). These patients also showed sensitivity to pollen extract of mustard plant which suggests strong crossreactivity. This phenonmenon could be due to the presence of some sharing chemical allergens in seed as well as in pollen. These patients also showed predominant symptoms of allergic rhinitis. In other study Jensen (1998) also pointed out crossreactivity pattern with pollen and food allergens. However, Pesterollo et al observed that pollen and food crossreactivity was not an important factor in a study conducted in southern Europe.  In our study, we observed that there was strong crossreactivity among pollen and mustard seed belonging to Brassicaceae family.
TABLE 2 :
Cutaneous sensitivity to different inhalant allergens
No. of patients
Mustard contains irritating substances such as isothiocyanates in Brassica nigra. These irritating substances may cause non immune reactions mimicking allergic reactions. Hence it was felt necessary to perform skin testing with both purified and fresh allergen extract of mustard. It is important to note that in our study, the size of the mustard skin prick test wheal and size of mustard pollen skin prick test wheal appeared to be significant. However skin prick test reactions with fresh extract (crude extract) of mustard seed were more erythematous. Similar results were also reported by Rance et al, by using fresh food extract. 
This reaction could be attributed to nonimmunological reaction due to irritating substances. It has been reported that a variety of substances are present in unpurified extract which may give rise to non-immunological reactions.
The treatment of food allergy is the elimination of the offending food. Not only, it should be the principal offending food, but also those closely related food substances containing cross-reacting antigens which can also give rise to the manifestations of the food allergy. In this study, we observed that patients sensitive to both pollen and mustard allergens had significant symptomatic relief when they avoided consumption of mustard in their diet. The degree of symptomatic relief was as high as sixty per cent.
Our results demonstrate the important position of mustard allergy in India. The high prevalence of mustard allergy may be probably linked to early consumption of mustard in diet in baby foods. It is suspected that the symptoms of mustard food allergy can be as serious as instances of anaphylaxis. It is suggested that screening test for food allergies may be done as it is difficult to eliminate mustard from the diet, as it is often hidden in food.
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