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Background: The existence of IgE binding to dog dander extract without IgE antibodies against the described dog allergens (Can f 1, 2, 3 and 4) implies the presence of other dog allergens yet to be identified. Recently, an IgE-binding protein was isolated from dog urine and identified as prostatic kallikrein; it has been named Can f 5. Cross-reactivity between a dog dander allergen and human prostate-specific antigen (PSA) has been described. The aim of this study was to identify the dog dander allergen that presents cross-reactivity with PSA and demonstrate its clinical relevance in our patient with human seminal plasma allergy. Methods: SDS-PAGE immunoblotting and inhibition tests were performed. Mass spectrometry was carried out to identify the protein involved in the allergy reactions. Results: SDS-PAGE immunoblotting-inhibition with an IgE-binding protein from dog prostatic secretion showed total IgE binding inhibition to a 28-kDa IgE-reactive band identified as PSA. The electroeluted protein from dog prostatic secretion was identified by mass spectrometry as Can f 5. IgE immunoblotting of human seminal plasma incubated with the serum of the patient revealed two IgE-binding bands (28 and 32.7 kDa). Both SDS-PAGE immunoblotting inhibition assays, with human seminal plasma or purified PSA in solid phase, showed complete IgE binding inhibition when the serum of the anaphylactic patient was preincubated with dog dander extract or recombinant Can f 5. Conclusions: The dog dander allergen that shows cross-reactivity with human PSA has been characterized and turns out to be the recently described Can f 5. We demonstrated the clinical relevance of this cross-reactivity in a patient. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: A considerable number of pollen-allergic patients develops allergy to plant foods, which has been attributed to cross-reactivity between food and pollen allergens. The aim of this study was to analyze the differences among pollen-allergic patients with and without plant food allergy. Methods: Eight hundred and six patients were recruited from 8 different hospitals. Each clinical research group included 100 patients (50 plant food-allergic patients and 50 pollen-allergic patients). Diagnosis of pollen allergy was based on typical case history of pollen allergy and positive skin prick tests. Diagnosis of plant-food allergy was based on clear history of plant-food allergy, skin prick tests and/or plant-food challenge tests. A panel of 28 purified allergens from pollens and/or plant foods was used to quantify specific IgE (ADVIA-Centaur® platform). Results: Six hundred and sixty eight patients (83%) of the 806 evaluated had pollen allergy: 396 patients with pollen allergy alone and 272 patients with associated food and pollen allergies. A comparison of both groups showed a statistically significant increase in the food and pollen allergy subgroup in frequency of: (1) asthma (47 vs. 59%; p < 0.001); (2) positive skin test results to several pollens: Plantago,Platanus,Artemisia,Betula,Parietaria and Salsola (p < 0.001); (3) sensitization to purified allergens: Pru p 3, profilin, Pla a 1 – Pla a 2, Sal k 1, PR-10 proteins and Len c 1. Conclusion: Results showed relevant and significant differences between both groups of pollen-allergic patients depending on whether or not they suffered from plant-derived food allergy. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]