Allergen content of grass pollen preparations for skin prick testing and sublingual immunotherapy

Background: The allergen content of diagnostics and immunotherapeutics is crucial for effective diagnosis and treatment. The aim of this study was to quantify and compare the allergen content of different grass pollen preparations for skin prick testing and sublingual immunotherapy (SLIT). Methods: Five skin prick test (SPT) solutions and 10 sublingual immunotherapeutics were analysed for protein and allergen concentration by Bradford assay, inhibition of IgE-binding to Phleum pratense ImmunoCAPs and content of the main allergen Phl p 5 by two-site enzyme immunoassay. In addition, the grass pollen preparations were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting analyses. Results: Protein concentrations of SPT solutions ranged from 15 to 427 mu g/ml, and Phl p 5 concentrations ranged from 0.15 to 18.3 mu g/ml. The ranking of SPT solutions concerning Phl p 5 content and IgE inhibition capacity was the same, and the ranking of protein and allergen content was closely correlated (r = 0.9). Protein content of the maintenance doses of the immunotheurapeutics ranged from 5 to 153 mu g, Phl p 5 content ranged from 0.2 to 21.6 mu g. IgE inhibition capacity of the maintenance doses was closely correlated to their Phl p 5 and protein content. SDS-PAGE and immunoblots confirmed the differences in protein and allergen content. Conclusions: Grass pollen preparations for SPT and SLIT varied greatly concerning protein and allergen content. Whereas this result corresponds to previous analyses results of SPT solutions, it was the first comparison of grass pollen immunotherapeutics. For diagnosis and therapy, these differences should be taken into account.