Clinicoimmunologic studies on Phoenix sylvestris Roxb. pollen: an aeroallergen from Calcutta, India

Background: This study highlights the allergenicity and allergenic componen ts of the pollen of Phoenix sylvestris Roxb. (PS), or date sugar palm, whic h is predominantly airborne in the air of Greater Calcutta. Methods:A 2-year aerobiologic survey was performed by Burkard sampler. PS p ollen extract was used in skin tests of allergic patients, fractionated by (NH4)(2)SO4 and the Sephacryl 5-200 column. The allergenicity of each fract ion was checked by skin test and IgE ELISA inhibition. The principal allerg enic fraction, Fr.IIa, was separated in 11% SDS-PAGE, and its allergenicity was confirmed by IgE ELISA inhibition and immunoblotting. Results: PS pollen grains were found to be prevalent in the air of the subu rban zone of Calcutta from January to March with a peak in February. The po llen extract showed high (44.07%) positive skin reaction on 540 respiratory allergic patients. Among the (NH4)(2)SO4 cut fractions, Fr.II was the most active one, and it was resolved into four subfractions in the Sephacryl S- 200 column. Fr.IIa was the principal allergenic fraction, showing the prese nce of two components of 33 and 66 kDa in SDS-PAGE. In IgE immunoblotting, both of the components were found to be allergenic. Conclusions: The PS pollen grain is an important aeroallergen from Calcutta , India. The 33- and 66-kDa components are the major allergens present in t he relevant pollen extract.