Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at NSU
Pomegranate (Punica granatum)
The pomegranate is the fruit of the Punica granatum, a tree native to southwest Asia and widely cultivated in the Mediterranean area. The pomegranate ripens in autumn and is consumed from September to December. The pulp of the fruit is composed of a cluster of fleshy, red-violet seeds.
Clinical features of pomegranate allergy
The first case ever reported of adverse reaction to pomegranate was in 1992 (J Investig Allergol Clin Immunol. 1992). In this case the researchers were unable to demonstrate an IgE-mediated mechanism (prick test, histamine release test and RAST with pomegranate were all negative). The history of tongue angioedema due to pomegranate intake was proven by a double blind oral challenge test. This report emphasizes the importance of clinical history and oral challenge test in the diagnosis of food allergy.
Several adverse reactions to pomegranate, including abdominal pain, itching, generalized urticaria, oropharyngeal pruritus and severe symptoms such as anaphylactic shock, bronchospasm, dyspnea, angioedema or laryngeal edema, have been described in recent years.
Polysensitization in patients allergic to pomegranate
In a study of 15 patients allergic to pomegranate, 13 had sensitivity to pollens, 10 to nuts, and eight to peach. Type I hypersensitivity was strongly suggested by the positivity of the skin prick test and demonstration of specifc IgE antibodies to pomegranate in some of the patient sera (custom made test by the investigators).
Diagnosis of pomegranate allergy
A prick-prick test (prick-puncture) with the fresh fruit can be useful in making the diagnosis of pomegranate allergy. Patients with pomegranate allergy are often sensitized to other allergens. "Prick-to-prick" skin test testing with the fresh food in question can enhance the sensitivity of the skin test (AAAAI Ask the Expert, 2012).
In-vitro tests in pomegranate allergy
A 29-kDa protein allergen has been identifed in this common Mediterranean fruit.
Lipid transfer proteins (LTPs) are a family of low molecular mass (7-9 kDa) polypeptides, the members of which share 35-95% sequence homology. These proteins are widely distributed throughout the plant kingdom and are receiving attention for their biochemical characteristics and biological activity.
The specific IgE testing for pomegranate has not been standardized as of year 2010, and is not currently commercially available.
Pomegranate should be considered a potential allergen in patients suffering anaphylaxis in autumn and living in countries where this fruit is consumed.
Treatment of pomegranate allergy
Persistent avoidance and epineprine as needed are the mainstays of management.
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