Examination of cocksfoot pollen (Dactylis glomerata) extracts by skin prick test in man, RAST-based allergen assay and protein content.
Three commercial preparations of cocksfoot pollen (Dactylis glomerata) from different manufacturers were compared by skin prick tests in man, allergen activity as measured by the RAST test and protein nitrogen unit (PNU) and total nitrogen (N) content. The skin prick tests were made on the forearm with the undiluted preparations and also with solutions of 1/5 and 1/25 dilutions. Three groups each of 9 subjects were tested and the sites for the 9 tests were determined by 3 different latin squares. Taking one of the preparations as having a potency of unity, the estimated potencies for the other two were 0.28 and 0.18 when the areas of the weals were measured by a graph paper method and they were 0.27 and 0.19 when the areas were calculated by taking the product of the longest diameter of the weal and that at right angles to it. No notable differences were observed when the solutions were inoculated at different test sites. The three preparations were ranked in the same order of potency by the skin prick test, by measurement of allergen activity as measured by a RAST-based allergen assay method using the sera of the test subjects, and by measurement of their PNU but not their total N content. Comparisons such as these could possibly lead to the production of allergen extract preparations of similar or with consistent potency.