Citrus Allergy from Pollen to Clinical Symptoms

Abstract

Allergy to citrus fruits is often associated with pollinosis and sensitization to other plants due to a phenomenon of cross-reactivity. The aims of the present study were to highlight the cross-reactivity among citrus and the major allergenic pollens/fruits, throughout clinical and molecular investigations, and to evaluate the sensitization frequency to citrus fruits in a population of children and adults with pollinosis. We found a relevant percentage of sensitisation (39%) to citrus fruits in the patients recruited and in all of them the IgE-mediated mechanism has been confirmed by the positive response to the prick-to-prick test. RT-PCR experiments showed the expression of Cit s 1, Cit s 3 and a profilin isoform, already described in apple, also in Citrus clementine pollen. Data of multiple sequence alignments demonstrated that Citrus allergens shared high percentage identity values with other clinically relevant species (i.e. Triticum aestivum, Malus domestica), confirming the possible cross-allergenicity citrus/grasses and citrus/apple. Finally, a novelty of the present work has been the expression of two phospholipaseA2 isoforms (PLA2 α and β) in Citrus as well as in Triticum pollens; being PLA2 able to generate pro-inflammatory factors, this enzyme could participate in the activation of the allergenic inflammatory cascade.

Identification of gibberellin‐regulated protein as a new allergen in orange allergy

“…Additionally, oropharyngeal symptoms were observed in 41.7% of orange GRP‐sensitized patients in this study. In an Italian study, 39% of 72 children and young adults with pollinosis were found to be sensitized to citrus fruits . However, in the present study, sensitization to Bet v 1 homologs and profilin, which is related to pollen food‐associated syndrome, was observed in two and three of our patients, respectively.…”

Anaphylaxis exclusivity in a single Citrus species

“…Iorio et al 5 found that C clementina pollen has profilins with DNA sequence homology to that of profilins from Malus domestica (apples) but not to profilins from C sinensis. 5 This parallels the findings in this case: the idea that C clementina expresses allergens not found in C sinensis or C reticulata (C clementina's ancestral species) but that are perhaps found in other plants.…”

Filaggrin inhibits generation of CD1a neolipid antigens by house dust mite–derived phospholipase

“…Indeed phospholipases are known to be present in many other allergens including pollens and fungal allergens (75, 76) and therefore activation of this pathway may facilitate the allergenic process. By producing type 2 cytokines, CD1a-reactive lipid-specific T cells may lead to down-regulation of filaggrin and anti-microbial peptide expression and thus compound physical and antimicrobial barrier dysfunction.…”