The effect of subcutaneous and sublingual birch pollen immunotherapy on birch pollen-related food allergy: a systematic review.

Background: Birch pollen-related food allergy (BPFA) is the most common type of food allergy in birch-endemic areas such as Western and Central Europe. Currently, there is no treatment available for BPFA. Due to the cross-reactivity between birch pollen and a range of implicated plant foods, birch pollen allergen immunotherapy (AIT) may be effective in the treatment of BPFA. In this study, we systematically evaluate the effectiveness of birch pollen-specific subcutaneous or sublingual immunotherapy in treating BPFA. Methods: A search was performed in the PubMed, Embase, and Cochrane libraries. Studies were independently screened by two reviewers against predefined eligibility criteria. The outcomes of interest were changes in (1) severity of symptoms during food challenge, (2) eliciting dose (ED), and (3) food allergy quality of life (FA-QoL). The validity of the selected articles was assessed using the revised Cochrane risk of bias tool. We focused on studies with the lowest risk of bias and considered studies with a high risk of bias as supportive. Data were descriptively summarized. Results: Ten studies were selected that included 475 patients in total. Seven studies were categorized into "high risk of bias" and three into "moderate risk of bias." The three moderate risk of bias studies, with a total of 98 patients, reported on severity of symptoms during challenge and on the ED. All three studies had a control group. Compared to the control group, improvement in severity of symptoms was observed during challenge in two out of the three studies and on the eliciting dose in one out of three. Only one study investigated the effect of birch pollen AIT on FA-QoL, showing that there was no significant difference between patients receiving subcutaneous immunotherapy or a placebo. Of the seven supportive studies, four had a control group and of those, three showed improvement on both severity of symptoms and ED. None of the supportive studies investigated the effect of the therapy on FA-QoL. Conclusion: This systematic review shows that there is not enough evidence to draw firm conclusions about the effect of AIT on BPFA. Future research is warranted that uses robust clinical studies that include long-term effects, QoL, and multiple BPFA-related foods.

A European-Japanese study on peach allergy: IgE to Pru p 7 associates with severity.

BACKGROUND: Pru p 3 and Pru p 7 have been implicated as risk factors for severe peach allergy. This study aimed to establish sensitization patterns to five peach components across Europe and in Japan, to explore their relation to pollen and foods and to predict symptom severity. METHODS: In twelve European (EuroPrevall project) and one Japanese outpatient clinic, a standardized clinical evaluation was conducted in 1231 patients who reported symptoms to peach and/or were sensitized to peach. Specific IgE against Pru p 1, 2, 3, 4 and 7 and against Cup s 7 was measured in 474 of them. Univariable and multivariable Lasso regression was applied to identify combinations of parameters predicting severity. RESULTS: Sensitization to Pru p 3 dominated in Southern Europe but was also quite common in Northern and Central Europe. Sensitization to Pru p 7 was low and variable in the European centers but very dominant in Japan. Severity could be predicted by a model combining age of onset of peach allergy, probable mugwort, Parietaria pollen and latex allergy, and sensitization to Japanese cedar pollen, Pru p 4 and Pru p 7 which resulted in an AUC of 0.73 (95% CI 0.73-0.74). Pru p 3 tended to be a risk factor in South Europe only. CONCLUSIONS: Pru p 7 was confirmed as a significant risk factor for severe peach allergy in Europe and Japan. Combining outcomes from clinical and demographic background with serology resulted in a model that could better predict severity than CRD alone.

Prevalence and Predictors of Uncontrolled Asthma in Children Referred for Asthma and Other Atopic Diseases.

BACKGROUND: Uncontrolled asthma in children is still highly prevalent despite the availability of effective asthma treatment. We investigated 1) the prevalence of uncontrolled asthma among children referred for asthma and referred for atopic diseases other than asthma (ie food allergy, allergic rhinitis or atopic dermatitis) to secondary care; and 2) the predictors associated with uncontrolled asthma. METHODS: All children (4 to 18 years) referred for asthma or atopic diseases other than asthma to 8 secondary care centers in The Netherlands were invited to an electronic portal (EP). The EP is a web-based application with several validated questionnaires including the ISAAC questionnaires and the Asthma Control Test (ACT). Children were eligible for inclusion in this study when their parents reported in the EP that their child had asthma diagnosed by a physician. The ACT was used to assess asthma control. Multiple predictors of asthma control (patient, asthma and atopic characteristics) were evaluated by univariable and multivariable logistic regression analyses. RESULTS: We included 408 children: 259 children (63%) with asthma referred for asthma and 149 children (37%) with asthma referred for atopic diseases other than asthma. Thirty-nine percent of all children had uncontrolled asthma: 47% of the children referred for asthma and 26% of the children referred for atopic diseases other than asthma. Predictors associated with uncontrolled asthma were a family history of asthma (odds ratio [OR] 2.08; 95% confidence interval [95% CI] 1.34 to 3.24), and recurrent upper and lower respiratory tract infections in the past year (OR 2.40; 95% CI 1.52 to 3.81 and OR 2.00; 95% CI 1.25 to 3.23, respectively). CONCLUSION: Uncontrolled asthma is highly prevalent in children with asthma referred to secondary care, even if children are primarily referred for atopic diseases other than asthma. Thus, attention should be paid to asthma control in this population.

A subset of walnut allergic adults is sensitized to walnut 11S globulin Jug r 4.

BACKGROUND: The role of sensitization to commercially available allergens of English walnut (Juglans regia) Jug r 1, 2 and 3 in walnut allergy has been previously investigated in walnut allergic adults and was unable to explain all cases of walnut allergy. OBJECTIVES: Identify recognized walnut allergens, other than the ones previously investigated (Jug r 1-3), in walnut allergic adults and determine the sensitization frequency and diagnostic value. METHODS: Three different in-house walnut extracts were prepared and analysed on SDS-PAGE blots to identify allergenic walnut proteins. Immunoblots and immunoprecipitation, followed by LC-MS analysis, were performed to screen for, and confirm, IgE binding to walnut allergens in selected walnut allergic adults. In a cohort of 55 walnut challenged adults, including 33 allergic and 22 tolerant, sensitization to native and recombinant walnut allergen Jug r 4 was assessed using immunoblotting and immuno-line blot (EUROLINE), respectively. RESULTS: Screening of sera of 8 walnut allergic adults identified Jug r 4 as an allergen in our population. In the total cohort of 55 subjects, 5 were positive for Jug r 4 on immunoblot and 10 on EUROLINE. All but one EUROLINE positive subject had a positive food challenge (sensitivity 27%, specificity 95%, PPV 90%, NPV 47%). All 5 subjects positive on immunoblot were also positive on EUROLINE. LC-MS analysis showed a lack of Jug r 4 in the ImmunoCAP extract. Co-sensitization to other 11S albumins (eg hazelnut Cor a 9) was common in Jug r 4 sensitized subjects, potentially due to cross-reactivity. CONCLUSIONS: Walnut 11S globulin Jug r 4 is a relevant minor allergen, recognized by 27% of walnut allergic adults. It has a high positive predictive value of 90% for walnut allergy. Specific IgE against Jug r 4 occurred mostly with concomitant sensitization to other walnut components, mainly Jug r 1.

2S protein Ara h 7.0201 has unique epitopes compared to other Ara h 7 isoforms and is comparable to 2S proteins Ara h 2 and 6 in basophil degranulation capacity.

BACKGROUND: Screening for specific IgE against 2S albumin proteins Ara h 2 and 6 has good positive predictive value in diagnosing peanut allergy. From the third 2S member Ara h 7, 3 isoforms have been identified. Their allergenicity has not been elucidated. OBJECTIVE: This study investigated the allergenicity of Ara h 7 isoforms compared to Ara h 2 and 6. METHODS: Sensitization of 15 DBPCFC-confirmed peanut-allergic patients to recombinant Ara h 2.0201, Ara h 6.01 and isoforms of recombinant Ara h 7 was determined by IgE immunoblotting strips. A basophil activation test (BAT) was performed in 9 patients to determine IgE-cross-linking capacities of the allergens. Sensitivity to the allergens was tested in 5 patients who were sensitized to at least 1 Ara h 7 isoform, by a concentration range in the BAT. 3D prediction models and sequence alignments were used to visualize differences between isoforms and to predict allergenic epitope regions. RESULTS: Sensitization to Ara h 7.0201 was most frequent (80%) and showed to be equally potent as Ara h 2.0201 and 6.01 in inducing basophil degranulation. Sensitization to Ara h 7.0201 together with Ara h 2.0201 and/or 6.01 was observed, indicating the presence of unique epitopes compared to the other 2 isoforms. Differences between the 3 Ara h 7 isoforms were observed in C-terminal cysteine residues, pepsin and trypsin cleavage sites and 3 single amino acid substitutions. CONCLUSION & CLINICAL RELEVANCE: The majority of peanut-allergic patients are sensitized to isoform Ara h 7.0201, which is functionally as active as Ara h 2.0201 and 6.01. Unique epitopes are most likely located in the C-terminus or an allergenic loop region which is a known allergenic epitope region for Ara h 2.0201 and 6.01. Due to its unique epitopes and allergenicity, it is an interesting candidate to improve the diagnostic accuracy for peanut allergy.

Specific IgE to peanut 2S albumin Ara h 7 has a discriminative ability comparable to Ara h 2 and 6.

BACKGROUND: Little is known on the clinical relevance of peanut 2S albumin Ara h 7. OBJECTIVE: To investigate the discriminative ability of Ara h 7 in peanut allergy and assess the role of cross-reactivity between Ara h 2, 6 and Ara h 7 isoforms. METHODS: Sensitization to recombinant peanut storage proteins Ara h 1, 2, 3, 6, and 7 was assessed using a line blot in sera from 40 peanut-tolerant and 40 peanut-allergic patients, based on food challenge outcome. A dose-dependent ELISA inhibition experiment was performed with recombinant Ara h 2, 6 and Ara h 7 isoforms. RESULTS: For Ara h 7.0201, an area under the ROC curve was found of 0.83, comparable to Ara h 2 (AUC 0.81) and Ara h 6 (AUC 0.85). Ara h 7 intensity values strongly correlated with those from Ara h 2 and 6 (rs = 0.81). Of all patients sensitized to 2S albumins Ara h 2, 6, or 7, the majority was co-sensitized to all three (n = 24, 68%), although mono-sensitization to either 2S albumin was also observed in selected patients (Ara h 2: n = 6, 17%; Ara h 6: n = 2, 6%; Ara h 7: n = 2, 6%). Binding to Ara h 7.0101 could be strongly inhibited by Ara h 7.0201, but not the other way around. CONCLUSIONS AND CLINICAL RELEVANCE: Specific IgE against Ara h 7.0201 has a predictive ability for peanut allergy similar to Ara h 2 and 6 and possesses unique IgE epitopes as well as epitopes shared between the other Ara h 7 isoform and Ara h 2 and 6. While co-sensitization to all three 2S albumins is most common, mono-sensitization to either Ara h 2, 6, or 7 occurs in selected patients, leading to a risk of misdiagnosis when testing for a single 2S albumin.

Efficacy of Treatment of Non-hereditary Angioedema.

Non-hereditary angioedema (AE) with normal C1 esterase inhibitor (C1INH) can be presumably bradykinin- or mast cell-mediated, or of unknown cause. In this systematic review, we searched PubMed, EMBASE, and Scopus to provide an overview of the efficacy of different treatment options for the abovementioned subtypes of refractory non-hereditary AE with or without wheals and with normal C1INH. After study selection and risk of bias assessment, 61 articles were included for data extraction and analysis. Therapies were described for angiotensin-converting enzyme inhibitor-induced AE (ACEi-AE), for idiopathic AE, and for AE with wheals. Described treatments consisted of ecallantide, icatibant, C1INH, fresh frozen plasma (FFP), tranexamic acid (TA), and omalizumab. Additionally, individual studies for anti-vitamin K, progestin, and methotrexate were found. Safety information was available in 26 articles. Most therapies were used off-label and in few patients. There is a need for additional studies with a high level of evidence. In conclusion, in acute attacks of ACEi-AE and idiopathic AE, treatment with icatibant, C1INH, TA, and FFP often leads to symptom relief within 2 h, with limited side effects. For prophylactic treatment of idiopathic AE and AE with wheals, omalizumab, TA, and C1INH were effective and safe in the majority of patients.

Component-resolved diagnosis and beyond: Multivariable regression models to predict severity of hazelnut allergy.

BACKGROUND: Component-resolved diagnosis (CRD) has revealed significant associations between IgE against individual allergens and severity of hazelnut allergy. Less attention has been given to combining them with clinical factors in predicting severity. AIM: To analyze associations between severity and sensitization patterns, patient characteristics and clinical history, and to develop models to improve predictive accuracy. METHODS: Patients reporting hazelnut allergy (n = 423) from 12 European cities were tested for IgE against individual hazelnut allergens. Symptoms (reported and during Double-blind placebo-controlled food challenge [DBPCFC]) were categorized in mild, moderate, and severe. Multiple regression models to predict severity were generated from clinical factors and sensitization patterns (CRD- and extract-based). Odds ratios (ORs) and areas under receiver-operating characteristic (ROC) curves (AUCs) were used to evaluate their predictive value. RESULTS: Cor a 9 and 14 were positively (OR 10.5 and 10.1, respectively), and Cor a 1 negatively (OR 0.14) associated with severe symptoms during DBPCFC, with AUCs of 0.70-073. Combining Cor a 1 and 9 improved this to 0.76. A model using a combination of atopic dermatitis (risk), pollen allergy (protection), IgE against Cor a 14 (risk) and walnut (risk) increased the AUC to 0.91. At 92% sensitivity, the specificity was 76.3%, and the positive and negative predictive values 62.2% and 95.7%, respectively. For reported symptoms, associations and generated models proved to be almost identical but weaker. CONCLUSION: A model combining CRD with clinical background and extract-based serology is superior to CRD alone in assessing the risk of severe reactions to hazelnut, particular in ruling out severe reactions.

Using Component-Resolved Diagnostics in the Management of Peanut-Allergic Patients.

Instead of relying on crude peanut extract, component-resolved diagnostics (CRD) uses sensitization to allergenic proteins within peanut. In this review, we describe the recent advances and future perspectives of the use of CRD in the management of peanut-allergic patients. There is strong evidence that sensitization to Ara h 2 is the best predictor for clinically relevant peanut allergy in children and adults. Isolated sensitization to other peanut components is only rarely present in patients with systemic reactions to peanut. It is, however, important to remark that cut-off points of sIgE to Ara h 2 that predict tolerance or allergy vary between different study populations, different age groups and geographical regions, and validation studies performed in different settings are necessary to implement cut-offs in daily practice. Future studies should focus on the role of CRD in risk-assessment early in life, predicting long-term tolerance and monitoring treatment responses following immunotherapy.

Rush immunotherapy for wasp venom allergy seems safe and effective in patients with mastocytosis.

BACKGROUND: Patients with mastocytosis and wasp venom allergy (WA) may benefit from venom immunotherapy (VIT). However, fatal insect sting reactions have been described in mastocytosis patients despite previous immunotherapy. We investigated the safety and efficacy of (rush) VIT in patients with mastocytosis and WA. OBJECTIVE: To investigate the safety and efficacy of (rush) VIT in patients with mastocytosis and WA. METHODS: We describe nine patients with cutaneous mastocytosis and WA who received VIT. Cutaneous mastocytosis was confirmed by histopathology and systemic mastocytosis was diagnosed according to World Health Organization criteria. VIT was given according to a rush protocol. Given the difference in safety and efficacy of VIT in patients with WA and honeybee venom allergy, we reviewed the literature for VIT with the focus on WA patients with mastocytosis and addressed the difference between patients with cutaneous versus systemic mastocytosis. RESULTS: Nine patients had WA and mastocytosis, of whom six had cutaneous mastocytosis, two combined cutaneous and systemic mastocytosis and one systemic mastocytosis. All patients received rush IT with wasp venom. Most patients had only mild local side effects, with no systemic side effects during the course of VIT. One patient had a systemic reaction upon injection on one occasion, during the updosing phase, with dyspnoea and hypotension, but responded well to treatment. Immunotherapy was continued after temporary dose adjustment without problems. Two patients with a previous anaphylactic reaction were re-stung, without any systemic effects. CONCLUSIONS: VIT is safe in cutaneous mastocytosis patients with WA, while caution has to be made in case of systemic mastocytosis. VIT was effective in the patients who were re-stung.

Position paper of the EAACI: food allergy due to immunological cross-reactions with common inhalant allergens.

In older children, adolescents, and adults, a substantial part of all IgE-mediated food allergies is caused by cross-reacting allergenic structures shared by inhalants and foods. IgE stimulated by a cross-reactive inhalant allergen can result in diverse patterns of allergic reactions to various foods. Local, mild, or severe systemic reactions may occur already after the first consumption of a food containing a cross-reactive allergen. In clinical practice, clinically relevant sensitizations are elucidated by skin prick testing or by the determination of specific IgE in vitro. Component-resolved diagnosis may help to reach a diagnosis and may predict the risk of a systemic reaction. Allergy needs to be confirmed in cases of unclear history by oral challenge tests. The therapeutic potential of allergen immunotherapy with inhalant allergens in pollen-related food allergy is not clear, and more placebo-controlled studies are needed. As we are facing an increasing incidence of pollen allergies, a shift in sensitization patterns and changes in nutritional habits, and the occurrence of new, so far unknown allergies due to cross-reactions are expected.

Objective eliciting doses of peanut-allergic adults and children can be combined for risk assessment purposes.

BACKGROUND: To improve food labelling strategies, information regarding eliciting doses (EDs) and the effect of patient characteristics on these EDs is necessary. OBJECTIVE: To establish EDs for objective and subjective symptoms and analyse the effect of sensitization levels and other patient characteristics on threshold distribution curves (TDCs). METHODS: Threshold data from 100 adults and 262 children with a positive food challenge were analysed with interval-censoring survival analysis (ICSA) and fitted to a TDC from which EDs could be extracted. Possible influencing factors were analysed as covariates by ICSA. A hazard ratio (HR) was calculated in case of a significant effect. RESULTS: TDCs for both objective and subjective symptoms were significantly different between adults and children (P < 0.001). Objective ED05 values, however, were comparable (2.86 mg peanut protein in adults and 6.38 mg in children). Higher levels of sIgE to Ara h 2 and peanut extract were associated with a larger proportion of patient groups reacting to a dose increase with objective symptoms (adults and children) or subjective symptoms (adults, in children a trend). Age had a similar effect in children (HR 1.05 for objective symptoms and 1.09 for subjective symptoms). Gender had no effect on TDCs. CONCLUSION AND CLINICAL RELEVANCE: Subjective and objective TDCs were different between adults and children, but objective ED05 values were comparable, meaning that threshold data from children and adults can be combined for elaboration of reference doses for risk assessment. Higher sIgE levels to Ara h 2 and peanut extract were associated with a larger proportion of both patient groups to react to a certain dose increase.

Omalizumab in patients with chronic spontaneous urticaria: a systematic review and GRADE assessment.

Chronic spontaneous urticaria (CSU) is characterized by the occurrence of hives, angio-oedema or both for a period of at least 6 weeks. Many patients remain symptomatic despite treatment with H1 antihistamines, even at higher doses. This systematic review assessed the quality of the evidence for the effects of omalizumab as treatment in patients with CSU. We searched PubMed, the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials up to 7 August 2014. Three review authors independently carried out study selection, risk of bias assessment and data extraction. Two review authors analysed the data. Five randomized controlled trials (RCTs), which included 1116 participants, were evaluated. All the RCTs were judged as having a low risk of bias. There was a statistically significant improvement in measures of disease activity and quality of life following treatment with omalizumab when compared with placebo [mean difference (MD) -11·58, 95% confidence interval (CI) -13·39 to -9·77 and MD -13·12, 95% CI -16·30 to -9·95, respectively]. Complete response and partial response were more frequent after treatment with omalizumab [risk ratio (RR) 6·44, 95% CI 3·95-10·49 and RR 4·08, 95% CI 2·98-5·60, respectively]. There was no difference in the proportion of participants reporting adverse events between the omalizumab and placebo treatment groups (RR 1·05, 95% CI 0·96-1·16). There was high-quality evidence to support the effectiveness and safety of omalizumab 300 mg per month for the treatment of CSU for up to 6 months.

The EuroPrevall outpatient clinic study on food allergy: background and methodology.

BACKGROUND: The EuroPrevall project aimed to develop effective management strategies in food allergy through a suite of interconnected studies and a multidisciplinary integrated approach. To address some of the gaps in food allergy diagnosis, allergen risk management and socio-economic impact and to complement the EuroPrevall population-based surveys, a cross-sectional study in 12 outpatient clinics across Europe was conducted. We describe the study protocol. METHODS: Patients referred for immediate food adverse reactions underwent a consistent and standardized allergy work-up that comprised collection of medical history; assessment of sensitization to 24 foods, 14 inhalant allergens and 55 allergenic molecules; and confirmation of clinical reactivity and food thresholds by standardized double-blind placebo-controlled food challenges (DBPCFCs) to milk, egg, fish, shrimp, peanut, hazelnut, celeriac, apple and peach. RESULTS: A standardized methodology for a comprehensive evaluation of food allergy was developed and implemented in 12 outpatient clinics across Europe. A total of 2121 patients (22.6% <14 years) reporting 8257 reactions to foods were studied, and 516 DBPCFCs were performed. CONCLUSIONS: This is the largest multicentre European case series in food allergy, in which subjects underwent a comprehensive, uniform and standardized evaluation including DBPCFC, by a methodology which is made available for further studies in food allergy. The analysis of this population will provide information on the different phenotypes of food allergy across Europe, will allow to validate novel in vitro diagnostic tests, to establish threshold values for major allergenic foods and to analyse the socio-economic impact of food allergy.

IgE recognition patterns in peanut allergy are age dependent: perspectives of the EuroPrevall study.

BACKGROUND: We tested the hypothesis that specific molecular sensitization patterns correlate with the clinical data/manifestation in a European peanut-allergic population characterized under a common protocol. METHODS: Sixty-eight peanut-allergic subjects and 82 tolerant controls from 11 European countries were included. Allergy to peanut and lowest symptom-eliciting dose was established by double-blind placebo-controlled food challenge in all but anaphylactic subjects. Information of early or late (before or after 14 years of age) onset of peanut allergy was obtained from standardized questionnaires. IgE to peanut allergens rAra h 1-3, 6, 8-9, profilin and CCD was determined using ImmunoCAP. RESULTS: Seventy-eight percent of peanut allergics were sensitized to peanut extract and 90% to at least one peanut component. rAra h 2 was the sole major allergen for the peanut-allergic population. Geographical differences were observed for rAra h 8 and rAra h 9, which were major allergens for central/western and southern Europeans, respectively. Sensitization to rAra h 1 and 2 was exclusively observed in early-onset peanut allergy. Peanut-tolerant subjects were frequently sensitized to rAra h 8 or 9 but not to storage proteins. Sensitization to Ara h 2 ≥ 1.0 kUA /l conferred a 97% probability for a systemic reaction (P = 0.0002). Logistic regression revealed a significant influence of peanut extract sensitization and region on the occurrence of systemic reactions (P = 0.0185 and P = 0.0436, respectively). CONCLUSION: Sensitization to Ara h 1, 2 and 3 is usually acquired in childhood. IgE to Ara h 2 ≥ 1.0 kUA /l is significantly associated with the development of systemic reactions to peanut.

Predictors of health-related quality of life of European food-allergic patients.

BACKGROUND: Although food allergy has universally been found to impair HRQL, studies have found significant differences in HRQL between countries, even when corrected for differences in perceived disease severity. However, little is known about factors other than disease severity which may contribute to HRQL in food-allergic patients. Therefore, the aim of this study was to identify factors which may predict HRQL of food-allergic patients and also to investigate the specific impact of having experienced anaphylaxis and being prescribed an EAI on HRQL. METHODS: A total of 648 European food-allergic patients (404 adults, 244 children) completed an age-specific questionnaire package including descriptive questions. Multivariable regression analyses were performed to develop models for predicting HRQL of these patients. RESULTS: For adults, the prediction model accounted for 62% of the variance in HRQL and included perceived disease severity, type of symptoms, having a fish or milk allergy, and gender. For children, the prediction model accounted for 28% of the variance in HRQL and included perceived disease severity, having a peanut or soy allergy, and country of origin. For both adults and children, neither experiencing anaphylaxis nor being prescribed an epinephrine auto-injector (EAI) contributed to impairment of HRQL. CONCLUSIONS: In this study, food allergy-related HRQL may be predicted to a greater extent in adults than in children. Allergy to certain foods may cause greater HRQL impairment than others. Country of origin may affect HRQL, at least in children. Experiencing anaphylaxis or being prescribed an EAI has no impact on HRQL in either adults or children.

Diagnostic accuracy of specific IgE to components in diagnosing peanut allergy: a systematic review.

The diagnostic accuracy of skin prick test (SPT) and specific IgE (sIgE) to peanut extract in diagnosing peanut allergy is suboptimal. Recent studies have evaluated sIgE to peanut components as a possible new diagnostic tool. The aim of our review was to systematically search the literature to assess the diagnostic value of sIgE to peanut components in diagnosing peanut allergy. A literature search was performed in PubMed, Embase and the Cochrane Library. Results were subsequently screened for in- and exclusion criteria. The quality of eligible studies was assessed using a standardized quality assessment tool (QUADAS-2). Data on sensitivity, specificity, and positive and negative likelihood ratios were extracted or calculated for a descriptive analysis. Twenty-two studies were eligible, of which 21 studies in paediatric populations. Most studies reported on sIgE to peanut extract (15) and sIgE to Ara h 2 (12), followed by SPT (9) and sIgE to Ara h 1 (7). All studies were at risk of bias or caused applicability concerns on at least one item of the quality assessment tool. The best combination of diagnostic accuracy measures of all diagnostic tests was found for sIgE to Ara h 2. This finding was independent of geographical location. Compared to SPT and sIgE to peanut extract, sIgE to Ara h 2 was mainly superior in diagnosing peanut allergy in case of a positive test result. Worst diagnostic accuracy measures were found in general for sIgE to Ara h 8 and sIgE to Ara h 9. sIgE to Ara h 2 showed the best diagnostic accuracy of all diagnostic tests to diagnose peanut allergy. Compared to the currently used SPT and sIgE to peanut extract, sIgE to Ara h 2 was superior in diagnosing peanut allergy and should therefore replace these tests in daily clinical practice, especially in children.

Peanut allergy is common among hazelnut-sensitized subjects but is not primarily the result of IgE cross-reactivity.

BACKGROUND: Hazelnut and peanut are botanically unrelated foods, but patients are often sensitized and allergic to both, for reasons that are not well understood. METHODS: To investigate molecular cosensitization and cross-reactivity to peanut in hazelnut-sensitized individuals, children (n = 81) and adults (n = 80) were retrospectively selected based on sensitization to hazelnut. IgE to hazelnut extract, Cor a 1, 8, 9 and 14, to peanut extract, Ara h 1, 2, 3, 8 and 9, and to Bet v 1 was determined by ImmunoCAP. Allergy to hazelnut and peanut was established by DBPCFC and/or detailed clinical history. Patients were either tolerant or displayed subjective or objective symptoms to either food. IgE cross-reactivity between hazelnut and peanut storage proteins was assessed by reciprocal ImmunoCAP inhibition experiments. RESULTS: Of the 161 hazelnut-sensitized subjects, 109 (68%) were also sensitized to peanut, and 73 (45%) had clinical expression of allergy to peanut that was not associated with the presence or severity of hazelnut allergy. Instead, it was associated with IgE reactivity to peanut storage proteins, in particular Ara h 2. No cross-reactivity could be detected between Ara h 2 and Cor a 14, and 2 of 13 subjects displayed extensive cross-reactivity between 11S globulins; in plasma of both individuals, Ara h 3 almost completely inhibited IgE binding to Cor a 9. CONCLUSIONS: Peanut allergy is not primarily the result of IgE cross-reactivity to hazelnut storage proteins. IgE to Cor a 14 and Ara h 2 may serve as useful markers of primary sensitization to hazelnut and peanut, respectively.