Purification and characterization of allergens from Parietaria officinalis pollen

Abstract

The aqueous extract of Parietaria officinalis pollen has been fractionated by ammonium sulphate precipitation, gel filtration on Sephadex G-25, chromatography on DE 52, dialysis, and gel filtration on Sephadex G-75. The allergenic activity, determined with skin test, was recovered both in the dialyzable (D1. D2, D3, D4) and non-dialyzable (ND1, ND2, ND3, ND4) fractions. The active fractions, heterogeneous with respect to molecular weight which was in the range of 12,000–41,000 daltons, shared common properties: they were glycoproteins and precipitated rabbit antiserum: the allergenic activity was resistant to heating at 100°C for 2 hr and to digestion with neuraminidase, while it was destroyed by extensive pronase digestion. Isoelectric points were between 4.6 and 6.4. The spectra of fluorescence emission and of u.v. absorption were determined. Carbohydrate content was 4.9% and 6.7% respectively for dialyzable (D) and non-dialyzable (ND) fractions. A fraction with higher molecular weight, precipitating antiserum but inactive with skin test, was also recovered. We suggest that these fractions are correlated biochemically, antigenically and in their allergenic properties.