Immunological cross-reactivity between olive and grass pollen: implication of major and minor allergens

Abstract

BackgroundGrasses and olive trees are the most common sources of allergenic pollen worldwide. Although they share some allergens, there are few studies analyzing the in vitro cross-reactivity between them. The aim was to define the cross-reactivity between Olea europaea and Phleum pratense using well-characterized sera of allergic children from Madrid, Spain.Methods66 patients (mean age 10.32+/−4.07 years) were included in the study. All suffered from rhinoconjuntivitis and/or asthma and had a positive skin test and/or specific IgE determination to olive and grass pollen. Serum sIgE to individual allergens was conducted and sIgE against different grass species and olive was also determined by ELISA. Inhibition assays were performed using two serum sources, containing, or not, sIgE to minor allergens. Mass spectrometry analysis was performed in both extracts.Results59/66 (89.39%) children had a positive sIgE determination by ELISA to grasses and 57/66 (86.36%) to olive pollen. There was no significant correlation between sIgE levels to grass and olive. Inhibition assays demonstrated no cross-reactivity between P. pratense and olive pollen when using the pool containing mainly sIgE to major allergens, whereas minimal to moderate cross-reactivity was detected when the serum contained high sIgE titers to minor allergens. Proteomic analyses revealed the presence of 42 common proteins in grasses and olive pollens.ConclusionNo in vitro cross-reactivity was observed when sIgE was mainly directed to major allergens. In our population, sensitization to olive and grasses is not due to cross-reactivity. The contribution of the major allergens seems to be determinant.

Sensitization to grass allergens: Phl p1, Phl p5 and Phl p7 Phl p12 in adult and children patients in Beja (Southern Portugal)

“…Approximately 65---85% of grass-sensitized patients are positive for these allergens, which is why they are deemed major allergens. 5,15 In this study, it was not detected in isolation but 44.4% of the patients presented positive values. Seven children and 13 adults with positive sensitization results were detected for this allergen, with the percentage of sensitized patients being higher in adults.…”

“…17 Phl p6 is an allergen associated with proteins that bind calcium ions. 15 It is sequentially very similar to Phl 5 and therefore the two exhibit cross-reactivity. There are few cases of exclusive positivity to this marker.…”

“…Approximately 90% of grasssensitized patients tested positive for this allergen, which is why it is considered a ''major'' allergen. 5,15,11 Two 2012 studies describe sensitization >90% and 92%, respectively. 3,7 In the present study, the Phl p1 allergen was the most frequent and was detected alone in 40% of patients and 91% tested positive.…”

Minor allergen patterns in birch pollen allergen products—A question of pollen?

“…Up to now, minor allergens are usually not controlled during the production of allergen products. Although some observations imply a link between more severe allergy symptoms and sensitization to minor allergens, their relevance for safety and efficacy of allergen products is virtually unknown and data from controlled clinical trials are lacking. While standardization of allergen product manufacturing and composition has generally advanced in the past decade, neither raw materials nor production processes or storage conditions are standardized with regard to minor allergens .…”

“…Likewise, sensitization to profilin was identified as a marker for more severe symptoms in grass pollen allergic patients . In addition, it has been reported that high IgE levels to minor allergens are often associated with extensive cross‐reactivities . Nevertheless, there exists only one published example of a minor allergen specification: After discovering that an elevated level of the glucanase Ole e 9 in some product batches was associated with an increased rate of adverse events during AIT, the respective manufacturer introduced a specification limiting the content of this minor allergen .…”