Anaphylaxis following the consumption of pumpkin seeds in a two-year-old child tolerant to its pulp – a case study and a minireview

Pumpkin and its seeds are increasingly consumed by children for their potential health benets. Each day, around 30% of teenagers consume nuts and seeds, including pumpkin seeds. However, there is some evidence that pumpkin seeds may exert allergenic effects and induce severe life-threatening anaphylaxis. Allergy for melon, cucumber, and zucchini, which belong to the same Cucurbitaceae family as pumpkin, are well known, opposite to pumpkin allergy. Few descriptions of allergic reactions associated with pumpkin have been published, especially in children. To date, three cases of pumpkin pulp and two seed cases have been reported among children. Our case report describes a case of pumpkin seed anaphylaxis in a child with good tolerance of pulp. showed that because of the basic dietary was The skin-prick test was positive for pumpkin seeds (5 mm) but negative for pumpkin pulp (1 mm); allergen-specic IgE was 1.34 kUA/L for seed, and 0.37 kUA/L for pulp. The component resolved diagnosis found IgE to sesame seed, buckwheat and walnut (storage proteins). Based on these ndings, severe anaphylactic reaction to pumpkin seeds was identied.


Abstract Background
Pumpkin and its seeds are increasingly consumed by children for their potential health bene ts. Each day, around 30% of teenagers consume nuts and seeds, including pumpkin seeds. However, there is some evidence that pumpkin seeds may exert allergenic effects and induce severe life-threatening anaphylaxis. Allergy for melon, cucumber, and zucchini, which belong to the same Cucurbitaceae family as pumpkin, are well known, opposite to pumpkin allergy. Few descriptions of allergic reactions associated with pumpkin have been published, especially in children. To date, three cases of pumpkin pulp and two seed cases have been reported among children. Our case report describes a case of pumpkin seed anaphylaxis in a child with good tolerance of pulp.

Case presentation
In the present study, a two-year-old child experienced anaphylaxis: generalized urticaria, swollen lips and increasing dyspnea following the consumption of pumpkin seeds. The history showed that although the child had been receiving elimination diet because of atopic dermatitis, the basic dietary element was pumpkin pulp. The skin-prick test was positive for pumpkin seeds (5 mm) but negative for pumpkin pulp (1 mm); allergen-speci c IgE was 1.34 kUA/L for seed, and 0.37 kUA/L for pulp. The component resolved diagnosis found IgE to sesame seed, buckwheat and walnut (storage proteins). Based on these ndings, severe anaphylactic reaction to pumpkin seeds was identi ed.

Conclusions
It is possible to develop pumpkin seed anaphylaxis in a child with a tolerance to pumpkin pulp. Pumpkin seeds allergens have not been well characterized. Homology between the amino acid sequences in storage proteins may indicate cross reactivity between different edible seeds and nuts.

Background
Like ax, poppy, sesame and sun ower seeds, pumpkin seeds are increasingly consumed for their potential health bene ts. Their polyunsaturated fatty acid content bestows cardioprotective effects, and their phytosterols possess antioxidant, antiin ammatory and immunomodulatory properties [1]. Each day, around 32.4% of teenagers consume nuts and seeds, including pumpkin seeds [2,3]. However, there is some evidence that pumpkin seeds may exert allergenic effects and induce anaphylaxis.

Case Presentation
A two-year-old boy was referred to hospital for generalized urticaria, swollen lips and increasing dyspnea, observed around 10 minutes after eating pumpkin seeds for the rst time in his life. Severe anaphylactic reaction was diagnosed.
Interview revealed a negative family history for allergies. The boy was born at 32 Hbd, body mass 1150 g/intrauterine hypotrophy; the pregnancy was the rst one for the mother; delivery was by Caesarean section, Apgar score six points. From the age of two months, the child displayed loose stools and skin lesions characteristic of moderate atopic dermatitis (AD), with periodicallyobserved severe courses of AD. The child was breastfed up to ve months of age (the mother was on a dairy-free and egg-free diet) followed by extensively hydrolysed formula based on whey protein at the end of breastfeeding. Due to persistent skin lesions (moderate-severe), an elimination diet was extended to the following months of life: wheat our, soybean, carrot, apple, celery, pear, corn, broccoli and potato were excluded. At 15 months, the diet comprised whey hydrolysate, millet, rice, turkey, rabbit, watermelon, peach and bananas.
At around 16 months, the child entered the care to the Allergology outpatient clinic. It was proposed that the diet should be expanded to include potato, corn, broccoli and pumpkin pulp, which was introduced into the diet and well tolerated. From the age of 16 months, the pumpkin pulp become one of the most favourite meals; it was the basic dietary element and eaten daily in large quantities. Until the age of two years, apart from the observed exacerbations of AD, no other symptoms were observed. The child had been receiving topical treatments and elimination diets.
At the age of 2.5 years, while at home, the child experienced a sudden episode of anaphylaxis within 10 minutes of consuming pumpkin seeds shelled by his mother. Generalized urticaria, lip swelling and dyspnoea were observed. Adrenaline, systemic glucocorticosteroids, salbutamol and antihistamines were administered at a nearby hospital, and the symptoms regressed. A pumpkin seed elimination diet was initiated. After the incident, the child was referred to our Clinic (the Department of Paediatrics, Allergology and Gastroenterology) for diagnosis. During his stay in the clinic, the only deviation from the norm during physical examination was the presence of mild symptoms of AD (Scorad 20 points). The skin-prick test (SPT) based on the prick-by-prick method was positive for raw pumpkin seeds (5 mm) but negative for roasted pumpkin seed (2 mm) and pumpkin pulp (1 mm); total IgE was 111.8 kU/L, allergen-speci c IgE (asIgE) was 1.34 kUA/L for seed, and 0.37 kUA/L for pulp. In addition, asIgE against cow milk (20 kUA/L), egg white (6.3 kUA/L), sesame (0.78 kUA/L) and hazelnut (2.0 kUA/L) were identi ed. The component resolved diagnosis (CRD) found medium to high level IgE to cow's milk protein, egg white, sesame seed and buckwheat (ISAC test). Sensitization to inhalant allergens was also determined: the ISAC test revealed Der p 1 (7.7 ISU-E), Der f 1 (10 ISU-E), Phl p 1 (7.5 ISU-E). Alternaria alternata asIgE was present at serum concentrations of 0.72 kUA/L and birch pollen asIgE at 0.68 kUA/l ( Table 1). Based on the history, symptoms and results of the testing, anaphylactic reaction to pumpkin seeds was identi ed. A pumpkin seed elimination diet was recommended. In addition, it was planned to verify previous elimination diets and continue AD treatment. Currently, the child eats a standard diet apart from grains, peanuts, tree nuts, raw egg white and raw milk. It is planned to perform further oral food challenges and to gradually broaden the diet; however, the mother of the child has strong concerns and reservations in this regard.
During follow-up, allergic asthma was diagnosed at the age of three years: the asthma is mild and seasonal, but well controlled.
Exacerbations of asthma are also experienced after exercise. Since three years old, the AD has remained in remission, although it worsens around spring. On one occasion, a rash was observed on the skin following contact with raw milk. The anaphylactic reactions have not recurred.
Although pumpkin allergy (PA) usually develops following consumption, reports suggest the possibility of exposure through skin contact and/or inhalation of raw pumpkin or pumpkin seed allergens, e.g. while carving pumpkin [6,9,13]. Also, PA appears to be more common in males, especially atopic patients; our patient is a boy with co-existing AD and asthma.
Among adults, only one case with anaphylaxis to pumpkin esh has been described, and six with anaphylaxis to pumpkin seeds (Table 2) [6,12].
PA can range from mild oral symptoms to severe life-threatening anaphylaxis. Most reactions are mild, manifesting as only local symptoms in the mouth and throat [7]. However, some patients display vomiting, angioedema (face and throat), urticaria, erythema, dyspnoea, syncope and shock [1,4,10,11]. Pumpkin pulp allergy can also manifest as food protein induced enterocolitis syndrome [14].
Similar to our case, most previous patients displayed positive prick-by-prick ST for pumpkin seeds, and positive serum asIgE for pumpkin seeds. The high allergenic potential of pumpkin seeds means that allergy symptoms, including severe anaphylaxis, can occur at low asIgE levels. In addition, it is important to consider pumpkin seed allergy in patients with an unclear history of anaphylaxis, even following a negative SPT [4].
In our patient, the interview was unambiguous, i.e. symptoms appeared immediately after the consumption of pumpkin seeds shelled from pumpkin by the child's mother, and tests con rmed IgE sensitization. Hence, the food challenge test was abandoned.
Some patients with PA have cross sensitization to plants from the Rosaceae and Cucurbitaceae families and to pollen such as ragweed [6].
The development of pumpkin seed allergy is not precisely understood as the allergens have not been well characterized [1,11]. Immunoblotting has identi ed proteins with a molecular weight of 14 kDa, possibly a pro lin homologue, and 12 kDa, possibly an LTP homologue, in the sera of patients with pumpkin seed allergy [9,11]. In the present patient, CRD did not identify asIgE for the cross-reactive panallergens LTP and pro lin, which may indicate that other proteins are involved in the anaphylactic reactions, e.g. 2S albumin, 7S and 11S globulin; these are highly anaphylactogenic storage proteins present in the seeds of many plants, including sesame and sun ower [15].
Sensitization to cross-reacting allergens may contribute to exacerbations of food allergy; however, the testing performed at 2,5 years did not indicate the possibility of cross-reactivity to liable allergens. Only a very low concentration of sIgE to birch pollen and a high level anti-Phl p 1 antibodies (the main allergen marker of sensitivity to various grasses such as Timothy grass) were found.
Co-factors may play a signi cant role in the development of anaphylactic reactions, including those associated with pumpkin seeds. While squash-dependent anaphylaxis has previously been observed in a child following exercise [16], the anaphylactic reaction observed in our patient was not accompanied by any additional factors which could enhance systemic reaction, such as exercise or medications.
High and medium asIgE levels were found for 2S sesame seed and buckwheat albumin, suggesting their presence in pumpkin seeds. 2S albumin proteins are present in peanuts, some tree nuts and many seeds (including sun ower and sesame seeds), and due to their disulphide bonds and glycosylation, they can cause severe IgE-dependent allergic reactions [11,15]. PA has been found to co-occur with allergies to sun ower, poppy, almond and hazelnut seeds [1,11].
Anaphylaxis case reports show that symptoms may develop after eating roasted seeds, indicating high allergen thermostability [1,4,10]. The prick-by-prick test with roasted pumpkin seeds was negative in our subject. The negative test result rules out the possibility that storage proteins may play a role, due to their exceptional stability; however, it does not negate the potential role played by other protein allergens. In a similar way to peanuts, raw pumpkin seeds contain speci c allergens, together with a suitable epitope composition, while roast seeds may possess proteins with different allergenicity: roasting may lead to the development of new epitopes, which are not recognised by the asIgE prepared for the raw pumpkin seeds. However, little data is available on this topic.
In addition, the activity of other potential allergens, such as LTP proteins and oleosins, which are also found in other seeds (e.g. peanuts, hazelnuts, sesame seed, soya and sun ower) should also be taken into consideration. LTP proteins show relatively low amino acid sequence homology with allergenic LTP proteins from other sources, and therefore may not give a positive result for other LTPs in the ISAC test. Both the oleosins and LTP demonstrate less resistance to thermal processes than storage proteins, which may be the cause of a negative prick-by-prick test result based on roast pumpkin seeds. It is not possible to rule out the possibility that these proteins may have played a role in the sensitisation of our patient. Therefore, it appears certain that these proteins present in raw pumpkin seed participated in the anaphylactic reaction in the described patient.
In our case report, asIgE was found for the walnut allergen Jug r 2-7S globulin. The 7S and 11S globulin proteins are contained in the seeds of legumes (soybeans, peanuts), also in tree nuts and sesame seeds. Hazelnut allergen Cor a 9 11S globulin asIgE has previously been identi ed in an eight-year-old boy with anaphylaxis after ingesting pumpkin seeds [1]. Homology between the amino acid sequences in storage proteins may indicate cross reactivity between different edible seeds, peanuts and tree nuts [15].
It is possible to develop pumpkin seed anaphylaxis in a child with a tolerance to pumpkin pulp. Pumpkin seeds allergens have not been well characterized. Homology between the amino acid sequences in storage proteins may indicate cross reactivity between different edible seeds and nuts. Our ndings are of special value, particularly in children, considering the current trend toward health foods. Pumpkin, sesame, sun ower, linen and poppy seeds should be included in the standard diagnostic procedures for food allergy.