QUANTITATION OF THE MAJOR ALLERGEN OF SEVERAL PARIETARIA POLLENS BY AN ANTI-PAR-1 MONOCLONAL ANTIBODY-BASED ELISA - ANALYSIS OF CROSS-REACTIVITY AMONG PURIFIED PAR-J-1, PAR-O-1 AND PAR-M-1 ALLERGENS

Background Plants of the genus Parietaria, Urticaceae family, represen t a major cause of pollinosis in the Mediterranean area. Different Par ietaria species crossreact to a great extent, but studies on the cross reactivity among the major allergens of these pollens have not been ca rried out so far. Objective To develop an immunochemical method to qua ntify the major Parietaria judaica allergen, Par j 1, as well as to ve rify the presence of Par j 1-like proteins in different Urticaceae pol lens. These proteins would be purified in order to study the cross-rea ctivity among them. Methods Immunoaffinity chromatography with a monoc lonal antibody, solid-phase enzyme-linked immunoassays and SDS-PAGE. R esults A monoclonal antibody-based ELISA for the quantification of Par j 1 has been developed. The assay has a sensitivity of 0.2 ng/mL and shows a high correlation with the allergenic activity of P. judaica ex tracts determined by radioallergosorbent assay (PAST) inhibition. By m eans of this assay, proteins homologous to Par j 1 were detected in P. officinalis and P. mauritanica. These proteins (Par o 1 and Par m 1, respectively) were purified by affinity chromatography using the same monoclomal antibody employed in the ELISA. Crossed-inhibition experime nts demonstrated that Par j 1, Par o 1, and Par m 1, competed for the binding of specific IgE from a P. judaica-sensitive patients serum poo l. Conclusion The results here described suggest that shared allergeni c epitopes are present in the three main allergens investigated, which may simplify the diagnosis and therapy for Parietaria allergy.