Cardoon allergy

To the Editor:

The cardoon (Cynara cardunculus), a Mediterranean plant,¹ belongs to the Compositae family closely related to the artichoke. This vegetable is very popular in France, Italy and Spain and the fleshy root and the buds are eaten raw or cooked.

There is no published information regarding cardoon allergy.

A 12-year-old boy reported asthma and rhinoconjunctivitis in the spring seasons during the last 6 years. He referred, as well, pruritus around mouth after eating nuts, apple, melon, peach, oranges and tomatoes and in the last year, pruritus in mouth and ears and lip swelling after eating raw cardoon. He tolerated cooked cardoon and artichoke.

The patient was tested with a battery of aeroallergenes comprising pollens (grass, Olea europaea, Artemisia vulgaris, Parietaria judaica, Platanus acerifolia and Chenopodium album), house-dust mites, fungi, and animal dander. He was also prick tested with commercial food extracts, including nuts (hazelnut, almond, peanut, sunflower seed, pistachio and walnut), fruits (peach, apple, orange and melon), green vegetables (tomato and cardoon), profiline and prick-by-prick with cooked and raw cardoon. Histamine phosphate (10 mg/mL) and sterile 0.9% saline were used as positive and negative controls, respectively.

Specific IgE to extracts from cooked and raw cardoon and pollens from L. perenne, O. europaea, A. vulgaris, P. judaica and P. acerifolia was measured by an immune assay (Enzyme AllergoSorbent Test {EAST})

SDS-PAGE Immunoblotting was performed according to the method of Laemmli.²

Separated protein bands were electrophoretically transferred to polyvinylidine difluoride (PVDF) essentially as described by Towbin et al.³ and blocked during one hour at room temperature with 5% defatted dry milk in Tris buffered saline. Membranes were incubated overnight at 4° C with patient's serum followed by anti-human IgE-horseradish peroxidase conjugate. Detection was carried out by a chemioluminiscent (Amersham ECL Plus Western Blotting Detection System. GE Healhcare). When Western inhibition assay was performed, patient serum was preincubated with the inhibition phases during four hours at room temperature, and afterwards the serum samples were incubated with the PVDF membrane and IgE binding revealed as described herein.

Doubled-blind, placebo-controlled oral challenge tests with raw and cooked cardoon were made.

Skin prick tests with pollen of grass, Olea europaea, Artemisia vulgaris, Parietaria judaica, Platanus acerifolia and nuts (hazelnut, almond, peanut, sunflower seed, pistachio and walnut) were all positive. The prick test with profiline was also positive.

Prick-by-prick with peach, orange, melon, apple and tomato were positive.

Prick-by-prick with raw cardoon was positive, 11×10 mm (with negative controls) and negative with cooked cardoon.

Specific IgE by means of EAST assay was positive to extracts from raw cardoon (0.6 kU/L; class 1), cooked cardoon (0.4 kU/L; class 1) and pollens from Lolium perenne (>100 kU/L; class 5), Olea europaea (>100 kU/L; class 5), Artemisia vulgaris (10.3 kU/L; class 3), Platanus acerifolia (12.5 kU/L; class 3) and Parietaria judaica (1.9 kU/L; class 2).

The protein composition of the raw cardoon extract was studied by the SDS-PAGE and Coomassie staining with protein bands ranging from 66 to 14 kDa being observed. The electrophoresed and electrotransfered raw cardoon extract was incubated with patient's serum, revealing a broad and intense IgE binding area between 97 and 20 kDa.

Western blotting inhibition of raw cardoon extract with patient serum showed a total IgE-binding inhibition when the serum sample was preincubated with pollen extracts from Lolium perenne, Olea europaea, Artemisia vulgaris, Parietaria judaica and Platanus acerifolia.(Figure 1).

Figure 1.

SDS-PAGE immunoblotting inhibition. Lane C: control serum, Lane 1: patient's serum, Lane 2: patient's serum preincubated with cardoon extract(1mg/ml)(Positive inhibition control), Lane 3: patient's serum preincubated with Lolium perenne pollen extract(1mg/ml), Lane 4: patient's serum preincubated with Olea europaea pollen extract(1mg/ml), Lane 5: patient's serum preincuabated with Platanus acerifolia pollen extract(1mg/ml) Lane 6: patient's serum preincubated with Artemisia vulagaris pollen extract(1mg/ml) Lane 7: patient's serum preincubated with lamb extract(1mg/ml) M: molecular weight marked proteins.

Oral challenge test with raw cardoon produced pruritus in mouth and lips swelling 30 min after the ingestion whereas oral challenge with cooked cardoon did not produce any kind of symptomatology.

We report a case of cardoon allergy confirmed by positive results in in vivo and in vitro tests. Our patient had personal antecedents of rhinoconjunctivitis and asthma due to inhalation of various pollens: Lolium perenne, Olea europaea, Artemisia vulgaris, Parietaria judaica and Platanus acerifolia. The symptomatology due to cardoon ingestion had taken place several years after the pollen allergy status began. We demostrated the existence of serologic cross-reactivity among proteins from cardoon and some others from the pollens against which the patient was sensitised.