Citrus allergy from pollen to clinical symptoms.

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

Clinical features of the three patients with citrus fruit allergy.

<p>Patient data, results of prick-to-prick (PPT) with fresh citrus fruit pulp and specific IgE (sIgE) against the main pollens, (<i>Phleum p., Olea e., Betula v., Corylus a</i>.), fruit extracts (orange, apple, peanut, wheat), recombinant allergens (rPhl p 1, rPhl p 12, rBet v 2, rPru p 3) and MuxF3-CCD.</p><p>A: Asthma; OAS: oral allergy syndrome; RC: rhino-conjunctivitis; yrs: years.</p

Primer sequences and amplicon characteristics for <i>Citrus sinensis</i> genes used in semi-quantitative and qRT-PCR.

*<p>The qRT-PCR efficiency and correlations; R² were determined with LinRegPCR software.</p

Primer sequences and amplicon characteristics of <i>Triticum aestivum</i> (wheat) and <i>Malus domestica</i> (apple) cross-allergens.

<p>Primer sequences and amplicon characteristics of <i>Triticum aestivum</i> (wheat) and <i>Malus domestica</i> (apple) cross-allergens.</p

ClustalΩ multiple sequence alignments of allergen sequences annotated in UniProtKB database.

<p>Identity degree values expressed as multiple sequence alignment percentages of <i>Triticum aestivum</i> (PROF_WHEAT, Uniprot ID P49232-34, B6EF35), <i>Phleum pratense</i> (PROF_PHLPR, Uniprot ID P35079, O24650, O24282) and <i>Cynodon dactylon</i> (PROF_CYNDA, Uniprot ID O04725) profilin proteins (<b>A</b>). Identity percentages obtained from <i>Citrus sinensis</i> Cit s 1 (GLP), Cit s 2 (PROFILIN) and Cit s 3 (nsLTP) multiple sequence alignments (<b>B</b>). First column: <i>Citrus sinensis</i> GLP (GLP_CITSI, Uniprot ID P84159) with those for <i>Triticum aestivum</i> (GER_WHEAT, Uniprot ID P15290, B9VR55, C3UZE8, P26759, Q9SM34, Q9LD27, Q70PK0) and <i>Betula pendula</i> (GLP_BETPN, Uniprot ID P85352-54, P85336). Second column: <i>Citrus sinensis</i> PROFILIN (PROF_CITSI, Uniprot ID P84177) with those of <i>Triticum aestivum</i> (PROF_WHEAT, Uniprot ID P49232-34, B6EF35), <i>Phleum pratense</i> (PROF_PHLPR, Uniprot ID P35079, O24650, O24282), <i>Cynodon dactylon</i> (PROF_CYNDA, Uniprot ID O04725), <i>Artemisia vulgaris</i> (PROF_ARTVU, Uniprot ID Q8H2C8-9), <i>Betula pendula</i> (PROF_BETPN, Uniprot ID A4K9Z8, P25816), <i>Parietaria judaica</i> (PROF_PARJU, Uniprot ID Q9XG85, Q9T0M8), <i>Olea europaea</i> (PROF_OLEEU, Uniprot ID O24169-71), <i>Arachis hypogaea</i> (PROF_ARAHY, Uniprot ID Q9SQI9, Q5XXQ5, D3K177), <i>Malus domestica</i> (PROF_MALDO, Uniprot ID Q9XF40-42), <i>Corylus avellana</i> (PROF_CORAV, Uniprot ID A4KA40-45, Q9AXH4-5). Third column: <i>Citrus sinensis</i> nsLTP (NLTP_CITSI, Uniprot ID Q8L5S8, Q6EV47) with those of <i>Triticum aestivum</i> (NLTP_WHEAT, Uniprot ID Q5NE27-31, Q2PCB0, Q2PCB7-8, Q2PCD1-2, Q84N29), <i>Artemisia vulgaris</i> (NLTP_ARTVU, Uniprot ID P0C088, C4MGH0-2, C4MGG9), <i>Parietaria judaica</i> (NLTP_PARJU, Uniprot ID P43217, P55958, O04403-4, Q40905), <i>Olea europaea</i> (NLTP_OLEEU, Uniprot ID B2BGS3), <i>Arachis hypogaea</i> (NLTP_ARAHY, Uniprot ID B6CEX8, B6CG41), <i>Malus domestica</i> (NLTP_MALDO, Uniprot ID Q5GLH0, Q9M5X7, Q5J026), <i>Corylus avellana</i> (NLTP_CORAV, Uniprot ID Q9ATH2). Data are presented as range of percentage identity values as it has been considered all the allergen isoforms annotated and reviewed in UniProtKB database.</p

Pollinosis patients' clinical features.

<p>Levels of specific IgE (sIgE) against the main pollens (<i>Phleum p., Parietaria j., Olea e., Betula v., Corylus a</i>.), fruit extracts (orange, apple, peanut, wheat), recombinant allergens (rPhl p 1, rPhl p 12, rBet v 2, rPru p 3) and MuxF3-CCD in children and young adults with pollinosis. The geometric mean values of sIgE were calculated on the 14 out of the 28 patients with a positive reaction to prick-to-prick (PPT) with fresh citrus fruit pulp who accepted to perform blood test.</p><p>g mean: geometric mean; N: number; sIgE: specific IgE; PPT: prick-to-prick test.</p>§<p>Calculated on the 72 patients enrolled in the study.</p><p>° Calculated on the 14 patients who perform blood test.</p