Comparison of three variations of the radioallergosorbent test-inhibition assay for measuring allergenic activity of grass pollen extracts

Three variations of the radioallergosorbent (RAST)-inhibition assay (RI) have been compared for measuring the allergenic activity of grass pollen extracts. The main difference between the three assays consisted in the solid supports to which the allergens were coupled. These supports were paper disks, microcrystalline cellulose, and Matrex. It could be demonstrated that all three variations of RI yielded almost identical results as expressed by their F value (F_o). Correlations between the three methods were highly significant (P < 0.001). Three independent valid assays showed an excellent reproducibility of each test system (P < 0.01). Three different preparations of each of the supports yielded highly reproducible F_o (0.76 ± 3% SD). Evaluation of the 50% inhibition values achieved with the different assays based on protein showed differences between the three supports. Provided the same allergen extract is coupled to the different solid supports and the results are related to a reference preparation, different laboratories using different forms of RI will be able to compare their results.