Quantitation of the major allergen of severalParietariapollens by an anti‐Par 1 monoclonal antibody‐based ELISA. Analysis of crossreactivity among purified Par j 1, Par o 1 and Par m 1 allergens

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Abstract
Summary: BackgroundPlants of the genusParietaria, Urticaceae family, represent a major cause of pollinosis in the Mediterranean area. DifferentParietariaspecies crossreuct to a great extent, but studies on the crossreactivity among the major allergens of these pollens have not been carried out so far.ObjectiveTo develop an immunochemical method to quantify the majorParieiarin judaicaallergen. Par j 1, as well as to verify the presence of Par j 1‐like proteins in different Urticaceae pollens. These proteins would be purified in order to study the cross‐reactivity among them.MethodsImmunoaffinity chromatography with a monoclonal antibody, solid‐phase enzyme‐linked immunoassays and SDS‐PAGE.ResultsA monoclonal antibody‐based ELISA for the quantisation 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 ofP. judaicaextracts determined by radioallergosorbent assay (RAST) inhibition.By means of this assay, proteins homologous to Par j I were detected inP. officinalisandP. 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 experiments demonstrated that Par j 1. Par o 1. and Par m 1, competed for the binding of specific IgE from aP. judaica‐sensitive patients serum pool.ConclusionThe results here described suggest that shared allergenic epitopes are present in the three main allergens investigated, which may simplify the diagnosis and therapy forParietariaallergy.