Group 5 determination in Pooideae grass pollen extracts by monoclonal antibody-based ELISA. Correlation with biologic activity.

A solid-phase, monoclonal antibody-based ELISA was set up to quantitate group 5 allergens in pollen extracts of wild and cultivated Pooideae grasses. The method was able to evaluate group 5 concentration in mass units with a sensitivity in the ng/ml range and a practical working range of 1-100 ng/ml. The group 5 ELISA was compared with rocket immunoelectrophoresis for determination of allergen levels in several Phleum pratense extracts, and a very good quantitative correlation was found (r = 0.98; P < 0.0001). A highly significant correlation (r > 0.8) was also obtained in comparing allergenic potency determined by RAST inhibition to group 5 content in several wild and cultivated grass species. The results proved the usefulness of the method in the standardization of Pooideae pollen extracts employed in diagnosis and treatment.

The main allergen of Olea europaea (Ole e I) is also present in other species of the Oleaceae family.

Three major pollen allergens from Fraxinus excelsior, Ligustrum vulgare and Syringa vulgaris belonging to the Oleaceae family were purified. Monoclonal antibodies previously raised against the main allergen of Olea europaea (Ole e I) were used for their purification by affinity chromatography. The three new purified allergens were able to bind human IgE from serum of olive-allergic patients in a way analogous to Ole e I. Crossed radioimmunoelectrophoresis of the four allergens, using anti-olive extract rabbit serum, showed a unique immunoprecipitation arc with the same characteristics. The four purified proteins had similar molecular weights on SDS-PAGE and the N-terminal sequences for the first 20 amino acids were identical. Furthermore, the concentration of the allergens could be determined using a two-side solid phase assay previously developed for the allergen Ole e I. Our results indicate that the four purified proteins share, to a great extent, antigenic and allergenic epitopes leading to cross-reactivities which could cause common clinical manifestations. We propose for the newly purified allergens the nomenclature of Fra e I, Lig v I and Syr v I.