Original Paper

Cultivar-Specific IgE-Epitopes in Date (Phoenix dactylifera L.) Fruit Allergy
Correlation of Skin Test Reactivity and IgE-Binding Properties in Selecting Date Cultivars for Allergen Standardization
A.A.A. Kwaasi^a, H.A. Harfi^b, R.S. Parhar^a, K.S. Collison^a, S.T. Al-Sedairy^a, F.A. Al-Mohanna^a

Departments of
^aBiological and Medical Research and
^bMedicine/Paediatric Section of Allergy and Clinical Immunology, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia

Address of Corresponding Author

Int Arch Allergy Immunol 2000;123:137-144 (DOI: 10.1159/000024432)

  Key Words

• Cultivars
• Date fruits
• ELISA
• Epitopes
• IgE
• Immunoblotting
• Major allergens
• Standardization

  Abstract

Background: Date fruits are allergenic and standardized extracts are required for diagnosis and therapy of this allergy. Since there are several cultivars of dates, this study was carried out to assess the allergenicity of different cultivars in order to select suitable source material for standardization. Methods: The protein profiles of 18 of the most commonly sold varieties were compared by SDS-PAGE and their relative allergenicity assessed by SPT and IgE-based ELISA and immunoblotting. Thirty-two date fruit-sensitive patients were skin tested with a pooled extract from all the cultivars. Six of the patients with high SPT results (3+) who volunteered were further tested with the 18 cultivars and their sera used in ELISA and immunoblotting. Results: Six of the cultivars gave high SPT-positive reactions in 4 of patients. Five of these high SPT-reactive cultivars gave high IgE ELISA scores (0.58) but individual cultivars varied in their number of IgE immunoblot bands. Cultivar-specific IgE-binding patterns indicated that only certain cultivars bound IgE at molecular weights of 14.3 and 27-33 kDa whilst all cultivars bound to a 54-58 kDa doublet. Cultivars that bind to the 14.3 and 27-33 kDa bands appeared to form the majority of the high SPT-reactive cultivars. When individual sera of 24 of the 32 SPT-positive patients were used in IgE immunoblots with the pooled cultivar extract, all sera bound IgE at 14.3 and 27-33 kDa and about 60% of sera bound to a 54-58 kDa doublet bands. Conclusions: These results indicate that allergenicity of date fruits is a cultivar-specific phenomenon. Sixty to 100% of sera from date fruit-allergic patients bind IgE to three major allergens of 14.3, 27-33 and 54-58 kDa. Five of the cultivars that evoke high SPT reactions, high IgE ELISA scores and bind IgE to the major allergens, can be selected for the preparation of 'in-house' allergen extracts and for allergen standardization.

Copyright © 2000 S. Karger AG, Basel

  Author Contacts

Correspondence to: Dr. Aaron A.A. Kwaasi
Biological and Medical Research Department
MBC-03, King Faisal Specialist Hospital and Research Centre
PO Box 3354, Riyadh 11211 (Saudi Arabia)
Fax +966 1 442 7858, E-Mail Aaron@kfshrc.edu.sa

  Article Information

Received: Received: December 27, 1999
Accepted after revision: July 5, 2000
Number of Print Pages : 8
Number of Figures : 6, Number of Tables : 1, Number of References : 21