Cultivar-specific epitopes in date palm (Phoenix dactylifera L.) pollenosis. Differential antigenic and allergenic properties of pollen from ten cultivars.

Pollen from ten staminate cultivars of the date palm (Phoenix dactylifera L.) were compared for their antigenic and allergenic potentials. Crude extracts from the various cultivars were tested in 6 atopic patients with confirmed allergy to date pollen in order to determine any differences or similarities in the antigenic and allergenic properties of these cultivars. Results of skin prick tests, ELISA, IgG and IgE immunoblot analyses, peripheral blood lymphocyte proliferation and concomitant interleukin-4 (IL-4) production indicated inter-cultivar heterogeneity. One of the cultivars, No. 8, failed to elicit any skin test reactivity or bind IgE in atopic sera as determined by ELISA, immunoblotting or any of the other parameters examined. However, there were individual differences in patient responses but in the main and contrary to the results obtained with cultivars No. 1, 2, 4, 5 and 8, five of the cultivars, namely No. 3, 6, 7, 9 and 10, showed more enhanced differential antigenic and allergenic properties. Our results strongly indicate that the antigenicity and allergenicity of date palm pollen is more of a cultivar-specific phenomenon than a species-specific phenomenon, which is governed by the number, quantities or both of the major allergen epitopes possessed by that variety or cultivar.