Sensitization to timothy grass pollen allergenic molecules in children

Abstract

BackgroundGrass pollens are significant elicitors of IgE-mediated allergic disease in the world and timothy (Phleum pratense) is one of the most important pollens of the family. Molecular and biochemical characterization of Phleum pratense has revealed several allergen components: rPhl p 1 and rPhl p 5 have been shown to be “Species Specific Allergens”, while the profilin rPhl p 12 and the calcium-binding protein rPhl p 7 are the principal Cross-Reactive components.MethodsIn this study the pattern of sensitization to rPhl p 1, rPhl p 5, rPhl p 7 and rPhl p 12 was analyzed in children with asthma and/or rhinoconjunctivitis and grass pollen allergy, in order to evaluate the frequency of sensitization to allergenic molecules of Phleum pratense among pediatric subjects allergic to grass pollen in a Mediterranean population. The correlation of sensitization to these Phleum allergenic molecules with IgE against grass pollen extract and its variation according to age and level of IgE against grass pollen extract were evaluated.ResultsIgE against to rPhl p 1 were found in 99% (205/207) of patients, to rPhl p 5 in 67% (139/207), to rPhl p 12 in 32% (66/207) and to rPhl p 7 only in 5% (10/207).Sensitization only to “Species Specific” (rPhl p1, rPhl p5) allergenic molecules of Phleum pratense was detected in 65% (135/207) of children. Our data show the predominant role of rPhl p 1 in pediatric populations as the most relevant sensitizing allergen detectable at all ages and at all levels of timothy grass pollen-specific IgE antibodies, while the importance of rPhl p 5 rises with the increase of patients’ age and with grass pollen IgE levels.ConclusionsThe assessment of sensitization to grass pollen allergenic molecules could help develop a better characterization of allergic sensitization in grass pollen allergy in children, which may be different in every patient. It could also enable clinicians to give more specific and effective immunotherapy, based on allergenic molecule sensitization.

Allergen extract vs. component sensitization and airway inflammation, responsiveness and new‐onset respiratory disease

“…The high overall correlation between IgE sensitization to allergen extract and the corresponding components in this study is in agreement with previous studies on measurements of IgE towards single allergen components [15][16][17][18]20]. Further, high concordance has been shown between the use of timothy extract and allergen components measured with multiplex technique [12,13].…”

“…Only a few epidemiological studies [11][12][13] have compared IgE testing towards allergen extracts with testing towards allergen components, and all these studies have had a cross-sectional design [14]. There is generally a high concordance between single and multiplex measurements of IgE to allergen components [11], as well as between measurements using allergen extract and the corresponding components [15][16][17][18][19][20]. However, differences have been reported for some allergens [12,13], with a subgroup of subjects being sensitized according to extract-based measurements, but not according to measurements using components.…”

Diagnostic relevance of IgE sensitization profiles to eight recombinant Phleum pratense molecules

“…In a German population of 101 grass pollen‐allergic adults, a higher frequency of IgE sensitization to both Phl p 1 and Phl p 4 (92%) was observed, however, in our population the frequency of IgE sensitization to Phl p 4 was lower (42.2%); the discrepancy with our study is likely due to the use of a native form of Phl p 4, which carries highly cross‐reacting CCD B‐cell epitopes. Altogether, these results further confirm that the IgE sensitization to Phl p 1 is sufficient in most cases to corroborate a diagnosis of grass pollen allergy . This conclusion may be of great relevance in diagnostic algorithms for grass pollen AIT. Phl p 7 – IgE sensitization to Phl p 7 (polcalcin) was relatively infrequent but strongly associated with asthma.…”

Phleum pratense molecular pattern across Italy

“…On the contrary, the pollen quantity significantly varied with a gradient from North to South with the exception of Liguria, where very low values were observed. The present molecular outcomes are substantially consistent with previous surveys conducted in Italy, that showed the preeminence of IgE reactivity to Phl p 1 and Phl p 5 (11)(12)(13). In particular, Phl p 1 appears as the most important species-specific Phl p allergen.…”

“…The second study, performed in Rome, enrolling children candidate to allergen immunotherapy (AIT), demonstrated that IgE sensitization profiles to Phl p are very heterogeneous, but molecular profile characterization allowed to tailor a personalized AIT (12). The last study, done in Central Italy, analysed the sensitization pattern to Phl p 1, 5, 7, and 12, in a group of allergic children (13). The author concluded that assessment of molecular profile is useful for giving a more specific and effective AIT.…”