Sabine Dölle1, Stephanie Hompes1, Lars Lange2 and Margitta Worm1*
1Allergy-Center-Charité, Department of Dermatology and Allergology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, DE-10117 Berlin, and 2Children’s Hospital, St Marienhospital, Bonn, Germany. *E-mail: firstname.lastname@example.org
Accepted September 25, 2012.
Broccoli (Brassica oleracea var. Italica) belongs to the mustard/cabbage family, Brassicaceae. Other vegetables in this botanical family are cauliflower, cabbage, turnip, kale and Brussels sprouts. All of these are regarded as replacement vegetables in the diet of subjects allergic to pollen-associated food.
We report here the case of a 42-year-old Caucasian woman, who experienced 2 anaphylactic episodes in the 6 months prior to presentation, following ingestion of vegetables including broccoli. She developed angioedema of the lips and dyspnoea twice, both times necessitating emergency treatment. The patient had previously experienced similar episodes of angioedema following ingestion of peach and chamomile tea. Once, she experienced generalized urticaria after eating tree nuts and berry fruits. The patient has a 20-year positive history of allergic rhinoconjunctivitis during the summer months. No other allergic diseases, such as atopic dermatitis, asthma or contact dermatitis, e.g. nickel sensitization were known. Due to paroxysmal tachycardia the patient took a beta-blocker during the onset of the reactions, which was switched to a calcium antagonist prior to the challenge procedures.
Skin-prick test (SPT) with commercial inhalant pollen allergens (ALK-Abelló, Wedel, Germany) was positive for grass (7 mm), mugwort (5 mm) and ambrosia (8 mm). SPT with food allergen extracts (ALK-Abelló) and fresh food were positive for native hazelnut and wheat extract (4 mm each), peanut extract, native lupin and raw broccoli (5 mm each) and for paprika spice (6 mm). SPT to the lipid transfer protein (LTP) from peach (5 mm) was also positive. Total immunoglobulin E (IgE) level (ImmunoCAP System, Thermo Fisher Scientific, Uppsala, Sweden) was 94.6 kU/l. Specific IgE (sIgE) was positive for mugwort (6.65 kU/l), grass (2.89 kU/l), bell pepper (0.83 kU/l), and LTP of peach (Pru p 3, 12.30 kU/l) and mugwort (Art v 3, 1.76 kU/l). The sIgE for broccoli was below the detection limit (0.13 kU/l).
Double-blind, placebo-controlled food challenges (DBPCFC) were performed with bell pepper, lupin and broccoli. After ingesting cooked broccoli (80 g) the patient developed intensive long-lasting oral allergic symptoms with a mucosal erythema and a numbness of the tongue. The placebo, bell pepper and lupin challenges were negative.
As cooked broccoli elicited the symptoms in our patient, we suspected LTP to be the allergen responsible. LTPs are assumed to be highly thermostable and resistant to peptic digestion (1). It has been described that extensive heating can unfold LTPs, e.g. of wheat or barley (2, 3). However, those LTPs are structurally distinct from fruits and vegetables (4).
LTP in broccoli was identified in 1994 as the major protein on the surface of broccoli leaves (5). Homologous LTP is present in cabbage (Bra o 3) (6). LTPs are important food allergens causing severe reactions due to cross-reactivity among botanically related and unrelated fruit and vegetables (7, 8), but also local allergic symptoms have been reported in LTP-sensitized subjects (9). Thus, a link between inhalant sensitization to pollen LTP (such as Art v 3) and LTP-associated food allergy has been proposed (6, 10). In our patient the cross-reactive allergen may be Pru p 3, the peach LTP, but also Art v 3, the mugwort LTP, cannot be excluded as the patient has a history of rhinoconjunctivitis caused by mugwort pollen for several years.
Although, sIgE to broccoli was low, SPT and DBPCFC with broccoli were positive. One reason for the low IgE reactivity might be that the broccoli LTP is under-represented in the in vitro test system, resulting in false-negative results.
Thus far, no reports of broccoli allergy have been published. In the anaphylaxis-registry of German-speaking countries data from anaphylactic reactions have been collected since 2006 (11–13). Until 2010, a total of 2,114 anaphylactic cases were registered, of which 399 were caused by food and, more specifically, 34 were caused by vegetables (n = 34). However, only one anaphylactic reaction has been registered as being caused by a representative of the cabbage family (cauliflower). In this case, a 12-year-old boy developed urticaria, dyspnoea and a reduction in blood pressure after eating cauliflower in combination with physical activity (14). The registration of one severe allergic reaction during 4 years supports that cabbage-related food anaphylaxis is rare, but on the other hand cannot be excluded as such.
The authors declare no conflicts of interest.