Single-Species Grass Pollen Extracts and Mixtures of Extracts From Multiple Phylogenetically Related Grass Species Activate Allergic Patients' Basophils to the Same Degree

Abstract

RATIONALE: The necessity of complete identity between the sensitizing allergens and allergens used for immunotherapy has been debated. We have previously demonstrated that the effect of individual Derp2 isoforms on basophil activation is minimal, given a polyclonal IgE response (Christensen et al Journal of Immunology (2010) 184, 4966). Similarly, we here demonstrate that extracts of single-pollen and mixes of multiple grass species, respectively, activate basophils from grass-pollen allergic individuals to the same extent. METHODS: Blood basophils from grass allergic donors or basophils sensitized with IgE from grass allergic donors were incubated with either Phleum pratense, a 5-grass (Dac glo, Fes pra, Lol per, Phl pra, Sec cer) or 7-grass mix (Dac glo, Fes pra, Lol per, Phl pra, Poa pra, Arr ela, Sec cer). Activation was measured by flow cytometry. Also, alum-formulated vaccines in the form of Phleum pratense alone or grass mixes were compared in basophil activation assays. RESULTS: No differences in the ability of the single-species Phleum pratense extract and the 5- or 7-grass mixes to activate basophils from individual allergic donors were seen. Comparable responses were maintained after formulation of Phleum pratense and 5- and 7- species grass mixes with ALOH. CONCLUSIONS: Identical responses to single-species and multiple-species extract mixes in basophil activation assays indicate that in allergic individuals antibody responses to epitopes that are shared between different related grass species dominate over species-specific epitopes and -isoforms. This is in agreement with the confirmed clinically efficacy of single-species (Phleum pratense) grass pollen vaccines, both in subcutaneous and Allergy Immunotherapy Tablet regimens.