Comprehensive review of pollen-food allergy syndrome: Pathogenesis, epidemiology, and treatment approaches.

Pollen-food allergy syndrome (PFAS) is caused by cross-reaction of a specific pollen antigen with the corresponding food allergen in sensitized individuals. The manifestations are usually limited to oral symptoms; however, sometimes, rhinitis, respiratory and skin symptoms, and anaphylactic shock may occur. In PFAS pathogenesis, when food containing protein antigens (pan-allergens) with high homology to pollen antigens is ingested, mast cells bound to pollen antigen-specific IgE distributed in the oral mucosa cross-react with the food antigen, causing a local type I allergic reaction. The prevalence of PFAS depends on the geographic conditions, such as the type and amount of pollen in the area. PFAS is prevalent in all regions owing to the wide variety of pollen antigens implicated in the disease, such as alder and grass pollen, even outside of the birch habitat area. Basic research on PFAS is expected to significantly contribute to elucidating the pathogenesis and development of therapeutic strategies for PFAS. Currently, effective treatment for patients with PFAS that allows safe consumption of raw foods is lacking, and avoiding the intake of causative foods is the basis of prevention. Furthermore, allergen immunotherapy for PFAS has not yet been established, but various attempts are underway to develop it into a novel treatment strategy. This review highlights the current research landscape on the pathophysiology, epidemiology, and clinical aspects of PFAS. We outline the research gaps that should be addressed to improve the outcomes of patients with PFAS.

EAACI Molecular Allergology User's Guide 2.0.

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Profilin sensitisation in a Mediterranean population.

BACKGROUND: Sensitisation to pan-allergens has become an interesting tool for the study of the allergenic profile of different populations. Profilins are one of the most common pan-allergens to be studied because they are responsible for a large number of sensitisations and are clearly related to cross-reactivity and co-sensitisation. OBJECTIVES: The objective of this study was to investigate the profile of sensitisation to profilins and to correlate it with sensitisation to foods and pollens. METHODS: Six hundred and fifty-four consecutive patients were skin-prick tested with a battery of common allergens including pollens, epithelia, mites and moulds and profilin and divided into three groups depending on their sensitisation profile (non-atopic, atopic with pollinosis and atopic without pollinosis). Patients with symptoms were challenged and diagnosed with the offending food extracts. Profilin sensitisation was identified and analysed in detail. RESULTS: According to the classification of the population, the prevalence of profilin sensitisation was estimated at 2.9% in patients suffering respiratory allergy, 4.2% in atopic patients, and 5.9% in pollen-sensitised individuals. Positive association was observed between pollen (except Cupressus and olive) and profilin but not with moulds, mites or epithelia. With respect to foods, positive association was only observed between profilin and melon sensitisation. Lastly, in terms of symptoms, positive association was only observed between profilin sensitisation and OAS. CONCLUSION: Profilin sensitisation seems to be a marker of pollen-related poly-sensitisation in our area. Pan-allergen diagnosis seems to be an essential tool for developing and improving selection of the correct treatment for allergic patients.

Diagnostic usefulness of component-resolved diagnosis by skin prick tests and specific IgE to single allergen components in children with allergy to fruits and vegetables.

INTRODUCTION: The accurate identification of sensitizing proteins in patients allergic to plant-derived foods is extremely important, allowing a correct dietary advice. We aimed to evaluate the diagnostic usefulness of skin prick tests (SPT) and specific IgE (sIgE) with single molecular allergen components in children with allergy to fruits and vegetables. METHODS: Twenty children underwent SPT with a palm profilin (Pho d 2, 50 µg/mL); a Mal d 1-enriched apple extract (2 µg/mL) (PR-10 allergen); and a peach Lipid Transfer Protein (LTP) (Pru p 3, 30 µg/mL). Detection of sIgE to rBet v 1, rBet v 2, Phl p 12 and Pru p 3 was also measured. RESULTS: Allergy to multiple fruits and vegetables was observed in 11 (55%) children. Sensitization by SPT to Pho d 2, Mal d 1, and Pru p 3 occurred in 5, 7, and 8 cases, respectively. LTP sensitization appeared to be associated with peach allergy but not with severe reactions, and profilins sensitization to melon and tomato allergy. Kiwi sensitization (12 cases), the plant-derived food that caused more allergic reactions, seemed mostly species-specific. The concordance of SPT extracts and sIgE to the corresponding pan-allergens was high for profilins (k=0.857) and LTP (k=0.706), while for PR-10 allergens it was absent (k=0.079). CONCLUSIONS: Pan-allergen sensitization in children with allergy to fruits and vegetables was common and often multiple. There was no association of severe reactions to LTP sensitization. The introduction of routine SPT to pan-allergens can be a simple and feasible way of improving diagnostic and therapeutic efficacy.

Pollen-induced allergic rhinitis in 1360 Italian children: comorbidities and determinants of severity.

BACKGROUND: Pollen-induced allergic rhinoconjunctivitis (AR) is highly prevalent and rapidly evolving during childhood. General practitioners may not be fully aware of the nature and severity of symptoms experienced by patients and might underestimate the prevalence of moderate or severe disease. Thus, the relevance of early diagnosis and intervention may be overlooked. OBJECTIVES: To investigate the severity of pollen-induced AR and its determinants in Italian children referred to allergy specialists and who had never received specific immunotherapy (SIT). METHODS: Children (age 4-18 yr) affected by pollen-induced AR who had never undergone SIT were recruited between May 2009 and June 2011 in 16 pediatric outpatient clinics in 14 Italian cities. Recruited children's parents answered standardized questionnaires on atopic diseases (International Study of Allergy and Asthma in Childhood, Allergic Rhinitis and its Impact on Asthma, Global Initiative for Asthma). The children underwent skin-prick test (SPT) with several airborne allergens and six food allergens. Information on socio-demographic factors, parental history of allergic diseases, education, perinatal events, breastfeeding, nutrition and environmental exposure in early life was collected through an informatics platform shared by the whole network of clinical centers (AllergyCARD™). RESULTS: Among the 1360 recruited patients (68% males, age 10.5 ± 3.4 yr), 695 (51%) had moderate-to-severe AR, 533 (39%) asthma, and 325 (23.9%) oral allergy syndrome (OAS). Reported onset of pollen-induced AR was on average at 5.3 ± 2.8 yr, and its mean duration from onset was 5.2 ± 3.3 yr. Only 6.2% of the patients were pollen-monosensitized, and 84.9% were sensitized to ≥3 pollens. A longer AR duration was significantly associated with moderate-to-severe AR symptoms (p 0.004), asthma (p 0.030), and OAS comorbidities (p < 0.001). CONCLUSIONS: This nationwide study may raise awareness of the severity of pollen-induced AR among Italian children who have never received pollen SIT. The strong association between pollen-induced AR duration and several markers of disease severity needs replication in longitudinal studies, while suggesting that countrywide initiatives for earlier diagnosis and intervention should be planned.

Food allergy and cross-reactivity-chickpea as a test case.

Chickpea has become one of the most abundant crops consumed in the Mediterranean and also in western world. Chickpea allergy is reported in specific geographic areas and is associated with lentil and/or pea allergy. We investigated cross-reactivity between chickpea and pea/lentil/soybean/hazelnut. The IgE-binding profiles of chickpea globulin and pea/lentil/soybean/hazelnut extracts were analyzed by immunoblotting and immunoblot-inhibition studies. Inhibition-assay with pea/lentil completely suppressed IgE-binding to chickpea globulin allergens, while not so in the reciprocal inhibition. Pre-absorption of sera with chickpea globulin caused the disappearance of IgE-binding to protein on an immunoblot of soybean/hazelnut protein extract. These results suggest that cross-reactivity exists between chickpea and pea/lentil/soybean/hazelnut. Chickpea allergy is associated with lentil and/or pea allergy, but evidently may not present independently. This, together with the described asymmetric cross-reactivity and phylogenetic aspects, suggest that chickpea allergy is merely an expression of cross-reactivity, caused by pea and/or lentil as the "primary" allergen.