Allergic respiratory disease represents a significant and expanding health problem worldwide. Allergic symptoms, such as asthma and hay fever, cause sleep impairment and reduce school and work performance. The cost to society is substantial. Allergen avoidance and pharmacotherapy cannot control the disease. Only allergy immunotherapy has disease-modifying potential and should be included in optimal treatment strategies. Allergy immunotherapy was first administered as subcutaneous injections and has been practiced for the past 100 years or so. Recently, tablet-based sublingual allergy immunotherapy (SLIT) was introduced with comprehensive clinical documentation. SLIT tablets represent a more patient-friendly concept because they can be used for self-treatment at home.

EudraCT, no 2006-001795-20; ClinicalTrials.gov, identifier NCT00389363.

Background: Allergy to taxonomically related species is a common phenomenon caused by the same immunological receptor cross-reacting to homologous allergens from different species. Knowledge of patterns of cross-reactivity is crucial for the selection of optimal products for diagnosis and for specific immunotherapy. The objective of this study was to investigate patterns of serum IgE cross-reactivity towards pollens from various grass species. Methods: With grass group 1 allergens as the representative group, amino acid sequence alignment, structural modelling and comparison of 3D surface characteristics were performed to exemplify the molecular basis of IgE cross-reactivity. IgE binding to extracts from ten different grass species was determined (total number of data pairs >19,000), and IgE inhibition experiments using Phleum pratense were performed. Results: Analysis of surface topography for group 1 grass allergens demonstrated ample space for IgE binding epitopes in surface areas conserved among Pooideae grasses. Significant correlation was observed between the serum IgE response to P. pratense extract and extracts from the other Pooideae grasses analyzed. P. pratense extract was demonstrated to inhibit the binding of IgE to the allergens in all of the extracts included in the investigation, indicating patient IgE to be primarily directed towards common epitopes. Conclusion: Extensive IgE cross-reactivity was observed towards the allergens of the Pooideae grasses, meaning that the immune system does not appear to distinguish based on the IgE level between the different species of this subfamily. The data suggest equal effect upon use of any of the Pooideae species for diagnostic as well as therapeutic purposes.

Extensive T and B cell cross-reactivity was observed towards the allergens of the Pooideae grasses, and the degree of B cell cross-reactivity was independent of the number of species included in the extract mixes. This implies that treatment with pollen extract of just one Pooideae species will affect the allergic responses caused by any of the temperate grasses in this subfamily.

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