Which Allergen Extract for Grass Pollen Immunotherapy? an in Vitro Study

Background: Grass pollen is a major cause of allergy throughout the world. The only treatment targeting the causes and not only the symptoms of allergy is specific immunotherapy (IT). A number of controlled trials demonstrated the efficacy of IT in grass pollen allergic subjects, most using extracts of multiple grasses but some using extracts of a single grass. The optimal grass extract for IT has not yet been established. Methods: This study is aimed at investigating the IgE-binding pattern in sera from IT-nave patients from central Italy with allergic rhinitis and/or asthma caused by grass pollen. A 5-grass extract was used (containing Dactylis glomerata, Poa pratensis, Lolium perenne, Antoxanthum odoratum and Phleum pratense) and compared to Phleum pratense alone, which is the most frequently used single grass extract, by the RAST-inhibition technique. Results: The 5-grass extract showed, by RAST-inhibition, a significantly higher binding compared to the Phleum pratense extract for Antoxanthum odoratum and Poa pratensis, while the two extracts for immunotherapy showed similar binding affinity for Phleum pratense and the non-Pooideae grass, Cynodon dactylon. Conclusions: The use of a mixed-grass pollen extract seems to be the optimal choice when applying specific IT in grass pollen-allergic subjects from the Mediterranean area.