Biomarkers predicting the controller dose of omalizumab in patients with chronic spontaneous urticaria.

BACKGROUND: Clinical trials showed the efficacy of 300 mg/4 weeks of omalizumab (OMA) during 6 months in patients with severe chronic spontaneous urticaria (CSU). Nevertheless, in real life, many patients require higher doses and/or longer treatment. This study assesses the real-life performance of OMA in severe CSU and identifies factors associated with the response. METHODS: CSU patients eligible for OMA were recruited prospectively. Clinical data and a blood test were collected before OMA initiation. Urticaria Activity Score 7 (UAS7) was calculated at baseline and every 3 months during OMA treatment. CSU control was defined as UAS7 <7 points. This work was partially sponsored by OMA manufacturer. RESULTS: Eighty-nine adults (19.1% males) with severe CSU were recruited. Median duration of CSU prior to OMA initiation was 2 years, and median severity by UAS7 at baseline was 24 points (range 10-42 points). OMA controlled 94.4% of patients, but 17.9% of responders required doses >300 mg/4 weeks. A blood basophil count >20 cells/µL (OR 13.33; 95% CI 3.32-52.63; p < .001) and the absence of hypothyroidism (OR 3.65; 95% CI 0.78-16.95; p = .099) were identified as predictive factors to achieve control with 300 mg/4 weeks. Twelve patients were able to stop OMA during the study (responders in remission, RR). RR had received OMA for a median of 29 months (12-53 months). Conversely, 32 patients had been on OMA for >29 months at the end of the study (active responders, AR). AR had received OMA for a median of 45 months (30-100 months). There were no significant differences in clinical or analytical factors between RR and AR patients. CONCLUSIONS: Low blood basophil count and the presence of hypothyroidism might serve as biomarkers for the controller dose of OMA in severe CSU patients.

Differences in molecular sensitization profiles between a Spanish and Latin American mite allergic patients.

BACKGROUND AND OBJECTIVE: To analyze the sensitization pattern to Dermatophagoides pteronyssinus and to associate the diagnostic findings and clinical severity in 218 allergic patients from two different continents. METHODS: Mite allergic patients were recruited by the Allergology departments from Latin America (n=88: Colombia, Costa Rica and Guatemala) and Spain (N=130). All patients had allergic rhinitis with or without asthma and positive skin prick test results to D. pteronyssinus. Specific IgE levels to D. pteronyssinus, D. farinae, Der p 1, Der p 2, and Der p 23 were quantified by ImmunoCAP system (ThermoFisher Scientific). Allergenic profile was also determined by western blot. Comparative Statistical analysis was performed by GraphPad software. RESULTS: Patients recognized most frequently Der p 2 (79%) followed by Der p 1 (73%), and Der p 23 (69%) allergens. The percentage of asthmatic patients increases with the number of sensitizations however none statistically significant differences were found. Interestingly, asthmatic patients presented the highest median levels of total IgE and specific IgE levels of D. pteronyssinus and molecular allergens, mainly Der p 2. Analysing the two different populations, Spanish patients were predominantly sensitized to Der p 2 (88.46%) and Der p 1 (83.84%), whereas Latin American population were more sensitized to Der p 23. CONCLUSION: Our data support the relevance of Der p 2 in mite allergy as the major allergen, with the high number of patients sensitized to it and its importance in the development of asthma. Sensitization to Der p 23 was more important in Latin America.

Mast Cell Activation Profile and TFH13 Detection Discriminate Food Anaphylaxis Versus Sensitization.

BACKGROUND AND OBJECTIVE: The prevalence of food allergy (FA) has increased significantly, and the risk of developing anaphylaxis is unpredictable. Thus, discriminating between sensitized patients and those at risk of having a severe reaction is of utmost interest. To explore mast cell activation pattern and T follicular helper (TFH) 13 presence in sensitized and food anaphylaxis patients. METHODS: Patients sensitized to Lipid transfer protein (LTP) were classified as anaphylaxis or sensitized depending on the symptoms elicited by LTP-containing food. CD34+-derived MCs from patients and controls were obtained, sensitized with pooled sera, and challenged with Pru p 3 (peach LTP). Degranulation, PGD2, and cytokine/chemokine release were measured. The TFH13 population was examined by flow cytometry in the peripheral blood of all groups. In parallel, LAD2 cells were activated similarly to patients' MCs. RESULTS: A distinguishable pattern of mast cell activation was found in anaphylaxis compared to sensitized patients. Robust degranulation, PGD2, and IL-8 and GM-CSF secretion were higher in anaphylaxis, whereas TFG- and CCL2 secretion increased in sensitized patients. Concomitantly, anaphylaxis patients had a larger TFH13 population. MC activation profile was dependent on the sera rather than the MC source. In agreement with that, LAD2 cells reproduce the same pattern as MCs from anaphylactic and sensitized patients. CONCLUSION: The distinct profile of mast cell activation allows to discriminate between anaphylaxis and sensitized patients. Pooled sera may determine mast cell activation independently of mast cell origin. Besides, the presence of TFH13 cells in anaphylaxis patients points to an essential role of IgE affinity.

Low levels of miR-143-3p are associated with severe chronic rhinosinusitis with nasal polyps.

microRNAs (miRNAs) are small, single-stranded, non-coding RNA molecules that regulate post-transcriptional gene expression. Accumulating evidence suggests their involvement in regulating various biological and pathological processes, including inflammation. Studies have revealed distinct expression patterns of miRNAs in Chronic Rhinosinusitis with (CRSwNP) and without (CRSsNP) nasal polyps (1). Specifically, miR-155 and miR-21 have been observed to be upregulated in CRSwNP, increasing and attenuating the expression of pro-inflammatory cytokines, respectively (2,3). Conversely, the downregulation of miR-34, miR-449, and members of the miR-200 family has been associated with impaired ciliogenesis and the regulation of epithelial-mesenchymal transition, respectively (4,5). Nonetheless, the direct role of miRNAs in CRSwNP is still being investigated.

Usefulness of the Nasal Allergen Provocation Test in the Diagnosis of Shellfish Allergy.

BACKGROUND AND OBJECTIVES: Shellfish allergy is a major cause of food allergy and anaphylaxis worldwide. Several allergenic proteins have been described in the last few years, but the only diagnostic tool that still enables discrimination between allergic and nonallergic sensitized persons is the oral food challenge (OFC). The aim of this study was to evaluate the usefulness of the nasal allergen provocation test (NAPT) as a diagnostic tool in shellfish allergy. METHODS: Forty-five patients with confirmed sensitization to shrimp by a positive skin prick test (SPT) result with a commercial shrimp extract were recruited and classified as sensitized-allergic or sensitized-nonallergic based on current tolerance to shrimp intake, the result of an OFC with a freeze-dried cooked shrimp mixture extract, or a recent history of anaphylaxis induced by shrimp ingestion. These patients and 10 controls not sensitized to shrimp underwent NAPT with a freeze-dried cooked shrimp mixture extract. The response was evaluated using acoustic rhinometry and a visual analog scale. RESULTS: Significant differences (P=.001) were found between the sensitized-allergic group (18/20 positive NAPT, 90%) and both the sensitized-nonallergic group (2/18 positive NAPT, 11.1%) and controls (0/10 positive NAPT). NAPT enables differentiation between allergic and nonallergic persons with a sensitivity of 90%, specificity of 89%, positive predictive value of 90%, and negative predictive value of 89%. CONCLUSIONS: Our results indicate that NAPT makes it possible to differentiate between sensitized symptomatic patients and sensitized tolerant patients and could be a valuable diagnostic tool when assessing shrimp allergy.

Consensus on the Definition of Control and Remission in Chronic Urticaria.

The terms control and remission and other key terms used in chronic urticaria (CU) such as flare-up, relapse, exacerbation, and recurrence have not been fully defined in the literature. Disease monitoring and treatment goals in clinical practice are not well established. After a qualitative appraisal of available evidence, we aimed to find a consensus definition of control and remission, clarify key terminology, provide guidance on how to monitor the disease, and establish treatment goals in clinical practice. A modified Delphi consensus approach was used. Based on a literature review, a scientific committee provided 137 statements addressing controversial definitions and terms, available patient-reported outcomes (PROs), and recommendations on how to measure therapeutic objectives in CU. The questionnaire was evaluated by 138 expert allergists and dermatologists. A consensus was reached on 105 out of the 137 proposed items (76.6%). The experts agreed that complete control and remission of CU could be defined as the absence of signs or symptoms while on treatment and in the absence of treatment, respectively. Consensus was not reached on the definition of other key terms such as flare-up, exacerbation, and recurrence. The panel agreed that the objective of therapy in CU should be to achieve complete control. PROs that define the degree of control (complete, good, partial, or absence) were established. An algorithm for disease assessment is provided. In conclusion, this work offers consensus definitions and tools that may be useful in the management of patients with CU.

A Specialized Therapeutic Approach to Chronic Urticaria Refractory to H1-Antihistamines Improves Disease Burden: The Spanish AWARE Experience.

OBJECTIVE: During its first year, the AWARE study assessed disease activity, patient quality of life (QOL), and treatment patterns in chronic urticaria (CU) refractory to H1-antihistamines (H1-AH) in clinical practice. METHODS: We performed an observational, prospective (24 months), international, multicenter study. The inclusion criteria were age ≥18 years and H1-AH-refractory CU (>2 months). At each visit, patients completed questionnaires to assess disease burden (Urticaria Control Test [UCT]), disease activity (7 day-Urticaria Activity Score [UAS7]), and QOL (Dermatology Life Quality index [DLQI], Chronic Urticaria Quality of Life Questionnaire [CU-Q2oL], and Angioedema Quality of Life Questionnaire [AE-QoL]). We present data for Spain. RESULTS: The study population comprised 270 evaluable patients (73.3% female, mean [SD] age, 48.9 [14.7] years). At baseline, 89.3% were prescribed a CU treatment. After 1 year, first- and second-line treatments became less frequent and third-line treatments became more frequent. At baseline, 47.0% of patients experienced angioedema; at 1 year, this percentage had fallen to 11.8%. The mean (SD) AE-QoL score decreased from 45.2 (28.7) to 24.0 (25.8). The mean (SD) UCT score decreased from 7.0 (4.5) to 12.1 (4.1). According to UAS7, 38.2% of patients reported absence of wheals and itch in the previous 7 days at 1 year compared with 8.3% at baseline. The mean (SD) DLQI score decreased from 8.0 (7.4) to 2.8 (4.6). At the 1-year visit, the percentage of patients reporting a high or very high impact on QOL fell from 29.9% to 9.6%. CONCLUSION: H1-AH-refractory CU in Spain is characterized by absence of control of symptoms and a considerable impact on QOL. Continuous follow-up of CU patients and third-line therapies reduce disease burden and improve patients' QOL.

ARADyAL: The Spanish Multidisciplinary Research Network for Allergic Diseases.

Thematic cooperative health research networks (RETICS) are organizational structures promoted by the Instituto de Salud Carlos III of the Spanish Ministry of Science with the objective of carrying out cooperative research projects addressing challenges of general interest for society as a whole in the field of health care. The RETICS of Asthma, Adverse Drug Reactions, and Allergy (ARADyAL) received funding in 2016 for a 5-year program (2017-2021). ARADyAL integrates basic and clinical research in the areas of allergy, immunology, genetics, nanomedicine, pharmacology, and chemistry, with special interest in research on new biomarkers and the design and evaluation of new interventions for allergic patients with severe phenotypes. The consortium comprises 28 groups across Spain, including 171 clinical and basic researchers, 17 clinical groups that cover more than 10 000 000 patients of all ages from urban and rural areas and 11 basic groups active mostly at universities and research institutes. ARADyAL has proposed a research program organized into 3 different areas focusing on precision medicine, as follows: Program 1, Mechanisms and prediction of adverse drug reactions and allergic diseases; Program 2, Toward a precise diagnosis of allergic diseases; and Program 3, Predicting interventions in allergic diseases. There is also 1 common program dedicated to training. The network has a Steering Committee and an External Advisory Scientific Committee, which advise the global network coordinator, who has recognized expertise in the field. ARADyAL is a unique meeting point for clinicians and basic scientists who are already working in allergy.

Hypersensitivity Reactions to Cancer Chemotherapy: Practical Recommendations of ARADyAL for Diagnosis and Desensitization.

Rapid drug desensitization has enabled first-line therapies in patients with drug hypersensitivity reactions to chemotherapeutic drugs including monoclonal antibodies. Desensitization is a safe and highly effective procedure, not only for IgE-mediated reactions, but also for those mediated by non-IgE mechanisms. The likelihood of breakthrough reactions during desensitization is low, and most are mild; in fact, moderate-to-severe reactions are infrequent. In this document, 16 allergy departments belonging to the Spanish research network ARADyAL present a review of the available scientific evidence and provide general guidelines for the diagnosis and management of drug hypersensitivity reactions to chemotherapeutic drugs and monoclonal antibodies. Emphasis is placed on the desensitization procedure.

IgE-Mediated Sensitization to Galactose-α-1,3- Galactose (α-Gal) in Urticaria and Anaphylaxis in Spain: Geographical Variations and Risk Factors.

BACKGROUND: The objectives of this study were to investigate the prevalence of sIgE to galactose-α-1,3-galactose (α-gal) in individuals with acute urticaria or anaphylaxis from different geographical areas of Spain and to evaluate the relevance of demographics and lifestyle as risk factors for this immune response. METHODS: Participants were recruited from allergy departments at 14 Spanish hospitals. Patients aged 18 years or older presenting with urticaria or anaphylaxis were enrolled into one of 2 arms: cases and controls. An interviewer-administered questionnaire collecting demographic data, lifestyle habits, and the presence of cofactors was obtained from each participant. sIgE to α-gal and total IgE were determined using ImmunoCAP. sIgE levels ≥0.35 kU/L were considered a positive result. RESULTS: The study population comprised 160 cases and 126 controls. The median age was 44 years. The overall prevalence of a positive result of sIgE to α-gal was 15.7%; this was higher in cases (26.3%) than in controls (2.4%). The sIgE anti-α-gal positivity rate ranged from 37.68% (rural) to 15.38% (semiurban), and 7.85% (urban). The rates of positivity were 46.32%, (Northern), 0.72% (Center), and 0% (Mediterranean). A positive result for sIgE to α-gal was associated with a history of tick bites, participation in outdoor activities, pet ownership, and ingestion of mammalian meats or innards before the onset of symptoms. Only alcohol consumption could be implicated as a cofactor. CONCLUSION: Sensitization to α-gal in patients with urticaria or anaphylaxis differs considerably between the 3 geographical areas studied and is related to tick bites.

Effects of Rupatadine on Platelet- Activating Factor-Induced Human Mast Cell Degranulation Compared With Desloratadine and Levocetirizine (The MASPAF Study).

BACKGROUND AND OBJECTIVE: Platelet-activating factor (PAF) is a lipid mediator involved in the pathophysiology of several allergic diseases, for example, in the amplification of mast cell (MC) activation in anaphylaxis. Rupatadine is an antihistamine with a demonstrated anti-PAF effect, although its capacity to inhibit PAF-induced MC degranulation has not been fully evaluated. Objectives: To compare the ability of rupatadine to inhibit PAF-induced MC degranulation with that of desloratadine and levocetirizine and to confirm the dual anti-H1 and anti-PAF activity of rupatadine. METHODS: The human MC line LAD2 and primary MCs (human lung tissue MCs [hLMCs]) were used. MC mediator release was evaluated using the b-hexosaminidase and histamine release assay. The effects of rupatadine (H1 antagonist + PAF receptor antagonist), desloratadine, and levocetirizine (H1 antagonists) on LAD2 and hLMCs were compared. The PAF receptor antagonists WEB2086, BN52021, and CV6209 were also tested. PAF receptor protein expression was evaluated in both LAD2 and hLMCs. RESULTS: CV6209 and rupatadine inhibited PAF-induced MC degranulation in both LAD2 and hLMCs. In LAD2, rupatadine (5 and 10 µM) and levocetirizine (5 µM), but not desloratadine, inhibited PAF-induced b-hexosaminidase release. Rupatadine (1-10 µM), levocetirizine (1-10 µM), and desloratadine (10 µM) inhibited PAF-induced histamine release. Rupatadine at 10 µM had an inhibitory effect on hLMC degranulation, but levocetirizine and desloratadine did not. CONCLUSIONS: This study shows that rupatadine and, to a lesser extent, levocetirizine, but not desloratadine, inhibit PAF-induced degranulation in both LAD2 and hLMCs. These findings support the dual antihistamine and anti-PAF effect of rupatadine in allergic disorders.

Immediate Reactions to More Than 1 NSAID Must Not Be Considered Cross-Hypersensitivity Unless Tolerance to ASA Is Verified.

BACKGROUND AND OBJECTIVES: Individuals who develop drug hypersensitivity reactions (DHRs) to chemically unrelated nonsteroidal anti-inflammatory drugs (NSAIDs) are considered cross-hypersensitive. The hallmark for this classification is that the patient presents a reaction after intake of or challenge with acetylsalicylic acid (ASA). Whether patients react to 2 or more NSAIDs while tolerating ASA remains to be studied (selective reactions, SRs). Objective: To identify patients with SRs to 2 or more NSAIDs including strong COX-1 inhibitors. METHODS: Patients who attended the Allergy Service of Hospital Infanta Leonor, Madrid, Spain with DHRs to NSAIDs between January 2011 and December 2014 were evaluated. Those with 2 or more immediate reactions occurring in less than 1 hour after intake were included. After confirming tolerance to ASA, the selectivity of the response to 2 or more NSAIDs was demonstrated by in vivo and/or in vitro testing or by controlled administration. RESULTS: From a total of 203 patients with immediate DHRs to NSAIDs, 16 (7.9%) met the inclusion criteria. The patients presented a total of 68 anaphylactic or cutaneous reactions (mean [SD], 4.2 [2.1]). Most reactions were to ibuprofen and other arylpropionic acid derivatives and to metamizole. Two different NSAIDs were involved in 11 patients and 3 in 5 patients. CONCLUSIONS: Patients with NSAID-induced anaphylaxis or urticaria/angioedema should not be considered cross-hypersensitive unless tolerance to ASA is verified.

Management of chronic spontaneous urticaria in routine clinical practice: A Delphi-method questionnaire among specialists to test agreement with current European guidelines statements.

BACKGROUND: Chronic spontaneous urticaria (CSU) is a frequent clinical entity that often presents a diagnostic and therapeutic challenge. OBJECTIVE: To explore the degree of agreement that exists among the experts caring for patients with CSU diagnosis, evaluation, and management. METHODS: An online survey was conducted to explore the opinions of experts in CSU, address controversial issues, and provide recommendations regarding its definition, natural history, diagnosis, and treatment. A modified Delphi method was used for the consensus. RESULTS: The questionnaire was answered by 68 experts (dermatologists, allergologists, and primary care physicians). A consensus was reached on 54 of the 65 items posed (96.4%). The experts concluded that CSU is a difficult-to-control disease of unpredictable evolution. Diagnostic tests should be limited and based on clinical history and should not be indiscriminate. Autoinflammatory syndromes and urticarial vasculitis must be ruled out in the differential diagnosis. A cutaneous biopsy is only recommended when wheals last more than 24h, to rule out urticarial vasculitis. The use of specific scales to assess the severity of the disease and the quality of life is recommended. In patients with severe and resistant CSU, second-generation H1-antihistamines could be used at doses up to four times the standard dose before giving second-line treatments. Omalizumab is a safe and effective treatment for CSU that is refractory to H1-antihistamines treatment. In general, diagnosis and treatment recommendations given for adults could be extrapolated to children. CONCLUSIONS: This work offers consensus recommendations that may be useful in the management of CSU.

Allergy rhinitis: similarities and differences between children and adults.

BACKGROUND: Allergic rhinitis (AR) is a highly prevalent disease worldwide. Although a number of studies have described AR, no studies compared children and adult AR populations. The objective was to compare the AR characteristics between two AR cohorts of children and adults. METHODS: Two AR cohorts (children and adults) from Spain were studied through observational cross-sectional multicentre studies. AR was classified based on classical (allergen exposure), original (o-ARIA), and modified (m-ARIA) ARIA criteria. AR was evaluated by Total 4-Symptoms Score (T4SS), and disease severity by Visual Analogue Scale (VAS, 0-100 mm). AR comorbidities were also evaluated. RESULTS: A total of 5,405 patients (1,275 children, 4,130 adults) were studied. According to symptoms duration, intermittent AR was more frequent in children than in adults. Using o-ARIA severity, more children than adults had moderate/severe AR while, using m-ARIA, more children than adults had severe AR. T4SS was higher in adults than in children. Moreover, VAS was also higher in adults than in children. In addition, asthma atopic dermatitis and conjunctivitis were more associated to children than adults with AR, the frequency of this comorbidities increasing according to higher severity. CONCLUSIONS: AR in children was more intermittent, severe, with less symptoms but with more comorbidities than in adults. These results suggest AR has similarities but also significant differences between children and adults.

Allergic rhinitis severity can be assessed using a visual analogue scale in mild, moderate and severe.

BACKGROUND: Allergic rhinitis is a global healthcare problem due to its high prevalence, impact on individuals and socioeconomic burden for the nations. Allergic rhinitis severity evaluation is the key to a correct treatment, prevention of comorbidities and improving the quality of life of patients. This evaluation should be made with a simple, easy, fast but accurate and reliable methodology, both in a primary care and specialist setting. The visual analogue scale (VAS) meets all requirements to be the ideal tool to assess allergic rhinitis severity and has already been validated by using a single cut-off point, but this classification in two degrees of severity suffer from not allocating the patients uniformly and from giving a blind interval to classify the patients when the score is between 5 to 6 cm. METHODOLOGY: The main objective of our study is to describe the optimal cut-off points by using a VAS to discriminate between three degrees of allergic rhinitis severity (mild, moderate, and severe) following the ARIA modified severity criteria that has been previously validated. Sensitivity, specificity, positive and negative predictive values just like receiver operating characteristic curves were used to select the best cut-off values. RESULTS: In a cross-sectional multicentre study with 3,572 patients included we have found that VAS has a significant correlation with nasal symptom score and quality of life and that the best cut-off points to differentiate between mild, moderate an severe allergic rhinitis are a VAS score of 4 and 7, respectively. CONCLUSIONS: Allergic rhinitis severity could be assessed in three degrees by using VAS in a simple, easy, and accurate method.

Comparable actions of omalizumab on mast cells and basophils.

BACKGROUND: Omalizumab (OmAb) has recently been approved for the treatment of diseases other than allergic asthma, including chronic urticaria. The exploration of the use of OmAb in chronic urticaria was based on the presence of IgE autoantibodies against autoantigens such as anti-IgE, anti-FcεRI, and IgE antibodies against thyroid peroxidase in certain patients with chronic urticaria. OmAb recognizes and sequesters free IgE to prevent its interaction with FcεRI. However, OmAb is equally and rapidly effective against autoimmune and non-autoimmune urticaria, suggesting the possible involvement of additional mechanisms of IgE. OBJECTIVES: We sought to investigate the in vitro mechanism of action of OmAb in mast cells and basophils. METHODS: Both LAD2 human mast cell line, previously sensitized with IgE, and ex vivo basophils were incubated with OmAb at different doses, analysing its effect on IgE-dependent events (e.g., degranulation, phosphorylation-mediated signalling, and eicosanoid release). RESULTS: We found that OmAb dissociates pre-bound IgE from mast cells and basophils, resulting in a reduction of proximal phosphorylation-mediated signalling events (Syk, PLCγ, and LAT) and in a decrease in degranulation and leukotriene synthesis. CONCLUSION: Our data prove the existence of common mechanisms of action of OmAb in mast cells and basophils that would explain its effectiveness and rapid effect in chronic urticaria and provide a basis for its use in other diseases mediated by these cells.

Molecular cloning of plane pollen allergen Pla a 3 and its utility as diagnostic marker for peach associated plane pollen allergy.

BACKGROUND: Non-specific lipid transfer proteins (nsLTP) are considered to provoke allergic symptoms to plane tree pollen, which are frequently associated with peach allergy. OBJECTIVE: The objective was to clone the cDNA of plane pollen nsLTP Pla a 3, to characterize IgE-binding and allergenic potency of recombinant Pla a 3 in comparison to its natural counterpart and peach nsLTP Pru p 3. METHODS: Natural Pla a 3 was purified from plane pollen and analysed by mass spectrometry (MS). Recombinant Pla a 3 was characterized by SDS-PAGE and CD spectroscopy. Specific IgE to extract, components of plane pollen and Pru p 3 was measured by ImmunoCAP in sera of patients allergic to either plane pollen (n = 10), peach (n = 15) or both (n = 15). Biological potency of the proteins was investigated by in vitro mediator release assays and IgE cross-reactivity by competitive ELISA. RESULTS: Two Pla a 3 isoforms were identified. Recombinant Pla a 3 showed high purity, structural integrity, IgE-binding capacity comparable to nPla a 3 and biological potency. Sensitization to plane pollen extract was confirmed in 24/25 plane pollen allergics. The frequency of sensitization to Pla a 3 was 53% among patients allergic to both plane pollen and peach and 10% among plane pollen allergics tolerating peach where most patients were sensitized to Pla a 1. Pla a 3 and Pru p 3 showed strong bi-directional IgE cross-reactivity in patients allergic to peach and plane pollen, but not in peach allergics tolerating plane pollen. Levels of IgE-binding were generally higher to Pru p 3 than to Pla a 3. CONCLUSION: Sensitization to Pla a 3 is relevant in a subgroup of plane pollen allergics with concomitant peach allergy. IgE testing with Pla a 3 may serve as a marker to identify plane pollen allergic patients at risk of LTP-mediated food reactions and thereby improve in vitro diagnostic procedures.