Distribution of allergen activity and identification of the main IgE-binding glycopeptide of Parietaria judaica pollen.

Parietaria judaica pollen extract was separated by preparative isoelectric focusing and showed two allergenic components (A1 and A2) heterogeneously distributed within the pH gradient (pH 3-10). By fused-rocket immunoelectrophoresis, A1 was detected from pH 3 to 10, whereas A2 was only found at pH values below 8. Both components, A1 and A2, showed IgE-binding ability throughout their pH ranges, as determined by crossed-radio immunoelectrophoresis. In addition, all the preparative isoelectric focusing fractions contained the main allergenic polypeptide of P. judaica (Pj10) when analyzed by SDS-PAGE. This polypeptide was shown to be a glycopeptide or to be bound to a glycoprotein with alpha-D-mannopyranoside or alpha-D-glycopyranoside residues. Implication of charged sugar residues in the wide distribution of P. judaica allergens in a pH gradient is discussed.