Oral allergy syndrome (OAS) has been also demonstrated to varying extents. In one instance 100% of allergic patients (Pastorello et al 1996) [158] , in another 89% (Fahlbusch et al1998) [52] and in a third 19% has OAS (Möller et al 1997) [404].

Children are more likely to have severe reactions (Lucas et al. 2004) [953]

Fresh kiwi (Gall et al. 1994; Voitenko et al. 1997) [955] [884]

Fresh kiwi pulp and kiwi rind extract (Huertas et al. 1999) [959]

Kiwi extract and purified thaumatin-like allergen (Gavrovic-Jankulovic et al. 2002) [956]

Fresh kiwi pulp, 2 commercially available kiwi extracts, and a homemade kiwi extract (Aleman et al. 2004) [958]

Lucas et al. 2003 summarised the clinical dificulty encountered by several authors. Skin testing with fresh fruit lacks standardization and commercial skin test extracts are significantly less sensitive. In addition, the specificity of fresh kiwi fruit for skin testing appears poor in subjects allergic to cross-reacting pollens or latex [1132]

Prick by prick with the fresh fruit (Gall et al. 1994) [955]

Prick to prick. A positive reaction was defined as a wheal diameter 3 mm larger than the negative control wheal (Voitenko et al. 1997) [884]

Prick by prick with the fresh fruit and prick with the extract. A wheal diameter 3 mm or greater in diameter compared with that produced by using the saline control was defined as a positive reaction. A histamine solution (10 mg/ml) was used as a positive control (Huertas et al. 1999) [959]

A wheal diameter 3 mm or greater in diameter compared with that produced by using the saline control was defined as a positive reaction (Gavrovic-Jankulovic et al. 2002) [956]

Prick-by-prick technique. A wheal diameter 3 mm or greater with erythema compared with that produced by using the saline control was defined as a positive reaction (Aleman et al. 2004) [958]

22 patients with a history of allergic reactions to kiwi fruit and birch pollen allergy. Ten patients had severe generalized symptoms such as angioedema, pharyngeal swelling, and dyspnea; 12 patients had oropharyngeal pruritus (Gall et al. 1994) [955].

Nine patients (Voitenko et al. 1997) [884]

Eight patients (Huertas et al. 1999) [959].

Seven patients who had symptoms after the ingestion of kiwi (Gavrovic-Jankulovic et al. 2002) [956].

Forty-three patients (31 female and 12 male patients) aged 5 to 54 years (median, 31.2 years) were enrolled in the study (Aleman et al. 2004) [958].

All 22 patients showed positive prick test reactions to birch pollen and kiwi (Gall et al. 1994) [955]

All patients showed positive skin prick test (Voitenko et al. 1997) [884].

The skin test with the fresh fruit was positive in all patients although the test was not performed in two patients because of the severity of the symptoms. The skin tests with kiwi rind extract were positive in one patient (Huertas et al. 1999) [959].

The thaumatin-like allergen elicited positive skin prick test responses in 4 of 5 patients. The test was positive in 5 of 5 patients using a kiwi extract (Gavrovic-Jankulovic et al. 2002) [956].

The results of skin testing performed with kiwi were positive in 100% of the patients, whereas positive skin responses with the 2 commercial extracts and the homemade kiwi extract were observed in 40%, 28%, and 35% of the patients, respectively (Aleman et al. 2004) [958]

Kiwi extracts (Moller et al. 1998) [115]; (Moller et al. 1997) [404]. Pieces of fresh fruit were homogenised in acetone at -40°C (cooling in dry ice), and the mixture stored overnight at -20°C. The precipitates were washed twice with acetone and once with acetone:diethylether (1:1, v:v, -20°C) , filtered and lyophilised. 1.5 gr of the obtained acetone powder was extracted with 30 mL of PBS (0.01M potassium phosphate and 0.15 M NaCl (pH 7.4)) for 60 min by ice cooling. The suspension was centrifuged for 60 minutes at 10,500g, and the supernatant was filtered.

Kiwi extract (Gall et al. 1994 [955]; Voitenko et al. 1997 [884]; Huertas et al. 1999 [959]; Aleman et al. 2004 [958]; Lucas et al. 2004 [953]

Phadebas RAST using home-made allergen discs (Gall et al. 1994) [955]

CAP: Values above 0.35 KU/l represented a positive result. RAST: Positive results were defined as values above 400 cpm. Histamine release (HR): HR >15 ng was considered positive (Voitenko et al. 1997) [884]

EAST. Results were expressed as EAST classes (1-4) (Moller et al. 1998) [115] (Moller et al. 1997) [404]

ELISA (Huertas et al. 1999) [959].

CAP. Values greater than 0.35 kU/l were considered positive (Gavrovic-Jankulovic et al. 2002) [956], (Lucas et al. 2004) [953]

ELISA and CAP (Aleman et al. 2004) [958].

22 patients with a history of allergic reactions to kiwi fruit and birch pollen allergy. Ten patients had severe generalized symptoms such as angioedema, pharyngeal swelling, and dyspnea; 12 patients had oropharyngeal pruritus (Gall et al. 1994) [955]

9 patients divided in two groups based on skin prick test and open challenge results. Group 1 included 8 kiwi allergic and birch pollen allergic patients. Group 2 included 1 kiwi allergic patient without allergy to birch pollen (Voitenko et al. 1997) [884].

29 patients (Moller et al. 1997) [404]

11 patients (Moller et al. 1998) [115].

8 patients (Huertas et al. 1999) [959].

7 patients who had symptoms after the ingestion of kiwi (Gavrovic-Jankulovic et al. 2002) [956].

43 patients (31 female and 12 male patients) aged 5 to 54 years (median, 31.2 years) were enrolled in the study (Aleman et al. 2004) [958].

45 subjects (Lucas et al. 2004)

Specific IgE to birch pollen could be detected in all 22 patients with kiwi allergy, and to pollen from other tree/grasses in the vast majority of cases. Patients with severe clinical symptoms to kiwi fruit showed moderately elevated IgE levels in response to kiwi fruits, whereas those with mild localized symptoms had no detectable IgE to kiwi fruits. Patients with kiwi allergy had higher IgE levels to birch pollen than patients with birch pollen allergy without signs of kiwi allergy (Gall et al. 1994) [955]

In the CAP system, five sera were positive: 4/8 from group 1 and 1/1 from group 2. In the RAST system four sera were positive: 3/8 from group 1 and 1/1 from group 2. Five patients in group 1 released histamine in a dose-dependent manner after stimulation with different concentrations of kiwi extracts (Voitenko et al. 1997) [884].

23 patients had specific IgE against kiwi (Moller et al. 1997) [404]

Seven patients had specific IgE against kiwi, banana, avocado and latex. Four sera contained specific IgE against three extracts but not kiwi (Moller et al. 1998) [115].

Specific IgE against fresh kiwi and kiwi rind was detected in 5 and 1 patients respectively (Huertas et al. 1999) [959].

The test was positive in 4 of 6 patients (Gavrovic-Jankulovic et al. 2002) [956].

Fifty percent of patients with kiwi allergy had specific IgE to kiwi (Aleman et al. 2004) [958]

Lucas et al. 2004 [953] determined a sensitivity of 60% and a specificity of 83% in 45 subjects. One atopic control had a false positive response.

The allergen extracts were separated in a discontinuous buffer system by sodium dodecylsulfate–polyacrylamide gel electrophoresis (SDS-PAGE) with a 6% stacking gel and a 7.5% to 20% separation gradient gel under reducing conditions (Pastorello et al. 1996) [158]

SDS-PAGE was performed in a vertical slab gel apparatus with a 16% separating gel and a 5% stacking gel in a discontinuous buffer system under either reducing or non reducing conditions (Voitenko et al. 1997) [884].

The allergen extracts were separated by sodium dodecylsulfate–polyacrylamide gel electrophoresis (SDS-PAGE) with a 5% stacking gel and a 13% separation gradient gel (Moller et al. 1998) [115].

SDS-PAGE was performed under reducing conditions using polyacrylamide gradient gels (Fahlbusch et al. 1998) [52].

The protein extracts were separated by SDS-PAGE with a 4% stacking gel and a 10% separation gradient gel under reducing conditions (Gavrovic-Jankulovic et al. 2002) [956].

The sample was run in SDS-PAGE gel (2.67% C and 15% T acrylamide) under reducing conditions (Aleman et al. 2004) [958].

Separated proteins were electroblotted to nitrocellulose paper (pore size 0.45 µm) by using a Trans-Blot Cell. The paper was first blocked in phosphate-buffered saline, pH 7.4, with 0.5% Tween-20 and then incubated in sera diluted 1:4. IgE binding was determined with iodine 125–labeled anti-human IgE antiserum followed by exposure on x-ray (Pastorello et al. 1996) [158].

Separated proteins were electroblotted to nitrocellulose membranes (pore size 0.45 µm). The membrane was first blocked in phosphate-buffered saline, pH 7.4, with 0.5% Tween-20 and then incubated in sera diluted 1:5. IgE binding was determined with alkaline phosphatase-marked monoclonal anti-IgE. The reaction was developed with 4-nitroblue tetrazolium and 5-bromo-4-chloro-3-indolyl phosphate as substrate (Fahlbusch et al. 1998) [52].

Separated proteins were electroblotted to nitrocellulose membranes (pore size 0.2 µm) using a semi-dry blotting apparatus. Cut strips of the membranes were blocked twice with 5% (w/v) skimmed milk powder and 0.1%, v:v, Teewn 20 in PBS. These were then allowed to react overnight with individual or pooled human sera appropriately diluted. For IgE blots, membranes were probed with rabbit anti-human IgE (1:4000, 60 min), biotinylated goat anti-rabbit IgG (1:6000, 60 min) and streptavidin-horseradish peroxidase conjugate (1:20 000, 20 min). The reaction was developed with 3,3',5,5'-tetramethylbenzidine-dioctylsodiumsulphosuccinate (Moller et al. 1998) [115]

Separated bands were electrophoretically transferred to P-Immobilon membrane (polyvinylidene difluoride). The membrane was incubated overnight with individual sera from patients and with a pool of sera from patients with positive IgE levels, as evaluated by means of direct ELISA. Specific IgE binding was detected with peroxidase-conjugated monoclonal anti-human IgE diluted 1:100. The reaction was developed with tetramethylbenzidin (Aleman et al. 2004) [958].

All 30 sera reacted with a band of about 30 kDa, and therefore it was identified as the major kiwi allergen. Eleven other components also bound IgE, but none of them could be considered a major allergen, that is, recognized by sera from at least half of these patients. 30% to 50% of the sera recognised components of 41, 38, 32, 28, 24, and 22 kDa which were considered to be allergens of intermediate importance. Less than 30% of the sera recognized other components of 64, 20, 17, 14, and 12 kDa which were considered to be minor allergens (Pastorello et al. 1996) [158].

Patients reacted to 10-12 kDa and 20-25 kDa proteins being the most common allergens in kiwi extracts. Patients from group 2 reacted strongly with a protein of 30 kDa and weakly with a 18 kDa band (Voitenko et al. 1997) [884].

The major allergens of 43 and 67 kDa were detected by 5 and 4 sera respectively (of 7 patients). 2 of these patients also reacted to a 22 kDa protein (Moller et al. 1998) [115].

Eight of the nine sera reacted with the 30 kDa protein. IgE-binding proteins were seen at 23 kDa (five sera), 43 kDa and 80 kDa (four sera) and >80 kDa (two sera) (Fahlbusch et al. 1998) [52].

A protein of 24 kDa was recognised as the most prominent band by all 7 sera. Additionally, actinidin (30 kDa) as well as bands of 27 and 25 kDa were also recognised although with different intensities (Gavrovic-Jankulovic et al. 2002) [956].

A pool of sera recognized several bands in a molecular weight range between 12 to 70 kDa. The most frequent IgE-binding band was recognized by 13 (54%) individual sera of 24 patients with kiwi allergy corresponding to actinidin (Act c 1), the major kiwi allergen. Seven (29%) patients recognized the band of 24 kDa, corresponding to a thaumatin-like protein, and this should be considered as an important kiwi allergen. Eight percent of patients recognized the 12-kDa band, and 16% recognized the 66-kDa band. Nonetheless, among patients not allergic to kiwi, 8 (42%) recognized the actinidin band, 26% reacted to the thaumatin-like protein, 16% reacted to the 12-kDa band, and 10% reacted to the 66-kDa band (Aleman et al. 2004) [958].

Patient had to chew a small piece of fresh kiwi (weighing about 2 g) for about 30 seconds and then spitting it out. If no symptoms occurred within a period of 15 minutes, the test was repeated with double the dose of kiwi. Then, until intense symptoms or signs of an OAS occurred, the challenge was repeated at 15-minute intervals with doubling doses to a maximum dose of 64 g. If the 32 g dose did not elicit a reaction, the patient was asked to swallow this dose, and the same procedure was followed with the final dose of kiwi (Pastorello et al. 1996) [158].

Buccal challenge was performed by chewing 5 g of fresh kiwi for 30 seconds and then spitting out the fruit. A reaction was considered positive if itching or swelling occurred in the mouth or oropharynx within 15 min (Voitenko et al. 1997) [884].

Double-blind food challenges proved difficult to interpret in some subjects, and the recipe and methodology changed in an attempt to overcome this. Recipe 1: Peeled, pureed pulp of kiwi fruit, including seeds, was masked in a sorbet or ice cream vehicle (at room temperature) that contained ground dried tea leaves and liquid food colouring. Recipe 2: Peeled, pureed pulp of kiwi fruit, including seeds, was masked in yogurt containing a mix of orange pulp, tea leaves and liquid food colouring. (Lucas et al. 2004) [953]

Two different drinks were prepared for the test meal, an active drink (with kiwi) and a placebo drink (without kiwi). Active drink (250 mL) consisted of 50 g fresh kiwi pulp, 10 g wheat semolina, 3.5 g vanilla and 150 mL, pineapple juice, and the placebo drink of 10 g wheat semolina, 3.5 g vanilla, 150 mL pineapple juice, 0.1 mL green liquid coloring, 0.15 mL yellow liquid coloring, 75 g pear pulp. (Aleman et al. 2004) [958].

No (Pastorello et al. 1996 [158]; Voitenko et al. 1997) [884]; (Lucas et al. 2004) [953]

Yes (Aleman et al. 2004) [958]; (Lucas et al. 2004) [953]

30 subjects (Pastorello et al. 1996) [158]

9 subjects (Voitenko et al. 1997) [884]

46 subjects with self-reported allergy to kiwi fruit (45 DBPCFC±open challenge, one open food challenge). Subjects ranged in age from 6 to 64 years (mean 33 years; SD 18 years), and included 12 children under the age of 15 years. (Lucas et al. 2004) [953]

33 patients reporting symptoms on eating kiwi and IgE sensitization to kiwi (prick-by-prick) (Aleman et al. 2004) [958]

Recipe 1: Four placebo doses were randomly dispersed with nine active doses in incremental doses of kiwi fruit (1, 10, 50, 100, 500, 1000, 2000, 4000, 8000 mg). The doses were given to the subject at intervals appropriate to the reported reaction time. This was generally 15 min. The subject wore a nasal clip whilst ingesting the challenge. Recipe 2: Three placebo doses were randomly dispersed with four active doses in incremental doses of kiwi fruit (2.5, 10, 20 and 60 g). The doses were given to the subject at intervals of 30 min. Subjects who had a negative or inconclusive DBPCFC were offered an open challenge with whole kiwi fruit (60 g). (Lucas et al. 2004) [953]

Increasing amounts (7.5, 25, 75, and 150 mL) of either active or placebo drink were administered so 1 mL of active drink contained 0.2 g of fresh kiwi pulp. The total amount of kiwi pulp administered to each patient before considering a negative DBPCFC result was 51.5 g. The median of the provocative dose eliciting a positive challenge was that corresponding to 1.5 g of fresh kiwi pulp (Aleman et al. 2004) [958]

27 patients presented oral allergy syndrome (Pastorello et al. 1996) [158]

Itching or swelling occurred in the mouth or oropharynx within 15 min (Voitenko et al. 1997) [884]

Thirty subjects received recipe one, 15 recipe two and one child had an open challenge. In total, 24 DBPCFCs were positive, 12 were negative and nine challenges were inconclusive. The inconclusive challenges were in subjects with subjective symptoms. They had symptoms that did not strictly correlate with the placebo/active dose regime, but who we believed were probably positive. The child who only had an open challenge developed swelling of the lips and facial erythema after 2.5 g of kiwi (25 mg protein). In addition, three subjects developed objective clinical signs suggestive of allergy during an open challenge following a negative or inconclusive DBPCFC. Therefore, 24 subjects (53%) had kiwi fruit allergy confirmed by DBPCFC, with a further four (total 60%) developing signs suggestive of IgE-mediated food allergy during an open challenge. We had hoped that recipe two would eliminate the inconclusive results in subjects with OAS, but this was not the case with two of 15 subjects having inconclusive symptoms with this improved recipe. (Lucas et al. 2004) [953]

Twenty (66%) of 33 patients had positive DBPCFC results with kiwi and negative results with placebo. Seventeen (85%) of the 20 patients complained of symptoms strictly localized to the oral cavity (OAS). In addition, one patient complained of OAS and angioedema, one patient experienced OAS and gastrointestinal symptoms, and one patient experienced OAS and urticaria. None of the patients had severe reactions during the challenge test. The results of the DBPCFCs with kiwi among the 10 patients who were allergic to latex were positive in 6 patients and negative in 2 patients (Aleman et al. 2004) [958]