Research

Usefulness of manufactured tomato extracts in the diagnosis of tomato sensitization: Comparison with the prick-prick method

Ángel Ferrer¹ , Ángel J Huertas² , Carlos H Larramendi³ , Jose L García-Abujeta³ , Joan Bartra⁴ , Jose R Lavín⁵ , Carmen Andreu¹ , Juan A Pagán⁶ , María A López-Matas⁷ , Enrique Fernández-Caldas⁷ and Jerónimo Carnés⁷

¹Allergy Service, Hospital Vega Baja, Orihuela, Alicante, Spain

²Allergy Service, Hospital General Básico de la Defensa, Cartagena, Murcia, Spain

³Allergy Service, Hospital Marina Baixa, Villajoyosa, Alicante, Spain

⁴Allergy Service, Hospital Clinic de Barcelona, Barcelona, Spain

⁵Allergy Service, Hospital General Básico de la Defensa, Valencia, Spain

⁶Allergy Service, Hospital Virgen de la Arrixaca, Murcia, Spain

⁷Research & Development Department, Laboratorios LETI, S.L., Tres Cantos, Madrid, Spain

author email corresponding author email

Clinical and Molecular Allergy 2008, 6:1doi:10.1186/1476-7961-6-1

Published:	9 January 2008

Abstract

Background

Commercial available skin prick test with fruits can be negative in sensitized or allergic patients due to a reduction in biological activity during the manufacturing process. Prick-prick tests with fresh foods are often preferred, but they are a non-standardized procedure. The usefulness of freeze-dried extracts of Canary Islands tomatoes, comparing the wheal sizes induced by prick test with the prick-prick method in the diagnosis of tomato sensitization has been analyzed.

The objective of the study was to assess the potential diagnostic of freeze-dried extracts of Canary Islands tomatoes, comparing the wheal sizes induced by prick test with the prick-prick method.

Methods

Two groups of patients were analyzed: Group I: 26 individuals reporting clinical symptoms induced by tomato contact or ingestion. Group II: 71 control individuals with no symptoms induced by tomato: 12 of them were previously skin prick test positive to a tomato extract, 39 were atopic and 20 were non-atopic. All individuals underwent prick-prick with fresh ripe peel Canary tomatoes and skin prick tested with freeze-dried peel and pulp extracts obtained from peel and pulp of Canary tomatoes at 10 mg/ml. Wheal sizes and prick test positivity (≥ 7 mm²) were compared between groups.

Results

In group I, 21 (81%) out of 26 patients were prick-prick positive. Twenty patients (77%) had positive skin prick test to peel extracts and 12 (46%) to pulp extracts. Prick-prick induced a mean wheal size of 43.81 ± 40.19 mm² compared with 44.25 ± 36.68 mm² induced by the peel extract (Not significant), and 17.79 ± 9.39 mm² induced by the pulp extract (p < 0.01).

In group II, 13 (18%) out of 71 control patients were prick-prick positive. Twelve patients (all of them previously positive to peel extract) had positive skin prick test to peel and 3 to pulp. Prick-prick induced a mean wheal size of 28.88 ± 13.12 mm² compared with 33.17 ± 17.55 mm² induced by peel extract (Not significant), and 13.33 ± 4.80 mm² induced by pulp extract (p < 0.05 with peel extract and prick-prick).

Conclusion

Canary peel tomato extract seems to be as efficient as prick-prick tests with ripe tomatoes to diagnose patients sensitized to tomato. The wheal sizes induced by prick-prick and peel extracts were very similar and showed a high correlation coefficient.