Determination of the allergenic activity of birch pollen and apple prick test solutions by measurement of beta-hexosaminidase release from RBL-2H(3) cells. Comparison with classical methods in allergen standardization

Background: A murine in vitro model of the allergic type reaction was set u p to determine the biologic activity of extracts without involvement of hum an beings. It is based on beta-hexosaminidase release from passively sensit ized RBL cells after allergen challenge. The intended application of this R BL cell assay in the field of quality control of allergenic extracts requir es its comparison with established methods. Methods: The activity of five standardized birch-pollen prick test solution s was determined in parallel by RBL assay, direct IgE binding, IgE-binding inhibition, major allergen content, histamine-release assay, and skin testi ng. Results: The RBL cell-release assay corresponded well to other methods if a reagin raised against natural birch-pollen extract was used for passive se nsitization. However, in the case of a reagin against recombinant Bet v 1, only a decreased activity was observed, presumably because a reduced number of epitopes were recognized by the monospecific reagin. In contrast to sta ndardized birch-pollen extracts, nonstandardized apple extracts showed poor activity in all assays. Conclusions: This murine model might be a useful tool in the quality contro l of allergenic extracts. It combines properties of assays based on standar dized antisera and of assays that consider IgE cross-linking properties.