Cosensitization to the 3 Nonhomologous Major Cashew Allergens Ana o 1, Ana o 2, and Ana o 3 Is Caused by IgE Cross-reactivity

Background: Cashew nuts often cause strong allergic reactions, which are even more severe than those of peanuts. Ana o 1 (vicilin), Ana o 2 (legumin), and Ana o 3 (2S albumin) are major cashew allergens. Cosensitization to all 3 nonhomologous cashew nut allergens has been observed. We hypothesize that this might be due to IgE cross-reactivity. Methods: IgE cross-inhibitions were performed with Ana o 1-3 using serum samples from cashew nut–allergic patients. The related hazelnut allergens Cor a 11, 9, and 14 were used as controls. For comparison, IgE cross-reactivity between the hazelnut allergens was investigated using serum samples from hazelnut-allergic patients. Results: The median percentages of cross-inhibition between Ana o 1, 2, and 3 were 84%-99%. In comparison, the median cross- inhibition values between hazelnut allergens were 33%-62%. The IC50 values revealed the highest IgE affinity to be to Ana o 3 and Cor a 14. Hazelnut legumin Cor a 9 inhibited IgE binding to Ana o 1, 2, and 3, with median percentages of 75%, 56%, and 48%, respectively. No cross-reactivity was observed between allergenic vicilins or between 2S albumins from cashew and hazelnut. Potentially cross-reactive peptides of Ana o 3 identified in silico overlapped with previously reported IgE epitopes of all 3 allergens. Conclusion: IgE with high affinity to Ana o 3 that cross-reacts with the other 2 major nonhomologous cashew nut allergens might be responsible for the high allergenic potency of cashew nut. These cross-reactive IgE types comprise the major fraction of specific IgE in cashew-allergic patients and might be responsible for cross-reactivity between unrelated tree nuts (AU)

Antecedentes: Los anacardos suelen provocar fuertes reacciones alérgicas, que son incluso más graves que las del maní. Ana o 1 (vicilina), Ana o 2 (legumina) y Ana o 3 (albúmina 2S) son los principales alérgenos del anacardo. Se ha observado cosensibilización a los 3 alérgenos no homólogos del anacardo. Nuestra hipótesis es que esto podría deberse a la reactividad cruzada de la IgE. Métodos : Se realizaron inhibiciones cruzadas de IgE con Ana o 1-3 utilizando muestras de suero de pacientes alérgicos al anacardo. Como controles se utilizaron los alérgenos de avellana relacionados Cor a 11, 9 y 14. A modo de comparación, se investigó la reactividad cruzada de IgE entre los alérgenos de la avellana utilizando muestras de suero de pacientes alérgicos a la avellana. Resultados : Los porcentajes medios de inhibición cruzada entre Ana o 1, 2 y 3 fueron del 84% al 99%. En comparación, los valores medios de inhibición cruzada entre alérgenos de avellana fueron del 33% al 62%. Los valores de IC50 revelaron que la mayor afinidad de IgE era Ana o 3 y Cor a 14. La legumina de avellana Cor a 9 inhibió la unión de IgE a Ana o 1, 2 y 3, con porcentajes medios de 75%, 56% y 48%. , respectivamente. No se observó reactividad cruzada entre vicilinas alergénicas ni entre albúminas 2S de anacardo y avellana. Los péptidos potencialmente de reacción cruzada de Ana o 3 identificados in silico se superpusieron con epítopos de IgE previamente informados de los 3 alérgenos. Conclusión : La IgE con alta afinidad por Ana o 3 que reacciona de forma cruzada con los otros 2 alérgenos principales no homólogos del anacardo podría ser responsable de la alta potencia alergénica del anacardo. Estos tipos de IgE de reacción cruzada comprenden la fracción principal de IgE específica en pacientes alérgicos al anacardo y podrían ser responsables de la reactividad cruzada entre frutos secos no relacionados (AU)

Co-sensitization to the three non-homologous major cashew allergens Ana o 1, Ana o 2 and Ana o 3 is caused by IgE cross-reactivity.

BACKGROUND: Cashew nuts often cause strong allergic reactions, even exceeding those of peanuts. Ana o 1 (vicilin), Ana o 2 (legumin) and Ana o 3 (2S albumin) are major cashew allergens. Co-sensitization to all three non-homologous cashew nut allergens has been observed. We hypothesize that this might be due to IgE cross-reactivity. METHODS: IgE cross-inhibitions were performed with Ana o 1-3 using sera from cashew nut allergic patients. Related hazelnut allergens Cor a 11, 9 and 14 were used as controls. For comparison, IgE cross-reactivity between the hazelnut allergens was investigated using sera from hazelnut allergic patients. RESULTS: Median percentages of cross-inhibitions between Ana o 1-3 were 84-99%. In comparison, medians of cross-inhibitions between hazelnut allergens were 33-62%. The IC50 values revealed the highest IgE affinity to Ana o 3 and Cor a 14. Hazelnut legumin Cor a 9 inhibited IgE-binding to Ana o 1, 2, and 3 with median percentages of 75%, 56%, and 48%, respectively. No cross-reactivity was observed between allergenic vicilins or between 2S albumins from cashew and hazelnut. In silico identified potentially cross-reactive peptides of Ana o 3 overlapped with previously reported IgE epitopes of all three allergens. CONCLUSIONS: IgE with high affinity to Ana o 3 that cross-reacts with the other two major non-homologous cashew nut allergens might be responsible for the high allergenic potency of cashew nut. These cross-reactive IgE comprises the major fraction of specific IgE in cashew allergic patients, and might be responsible for cross-reactivity between unrelated tree nuts.

Cashew nut allergy in Singaporean children.

BACKGROUND: There has been an increasing trend of nut allergies in Singapore. OBJECTIVE: The aim of this study was to review the clinical characteristics of children with cashew nut allergy. METHODS: A retrospective analysis was conducted in a tertiary paediatric referral centre in Singapore from 2008 to 2015. A total of 99 subjects with positive specific IgE (≥0.35 IU/L) to cashew nut were identified. Clinical features including demographics, clinical reaction to cashew nut, associations with other nuts and test specific measurements were recorded. RESULTS: The results showed that cutaneous symptoms (71.2%) were the most common allergic manifestations. Anaphylaxis occurred in 3.8% of children. In addition, all cashew nut allergic subjects were cross-reactive (either sensitized or allergic) to pistachio. Cross-reactivity rate with peanuts was 53.8%. There was a strong prevalence of atopy among cashew nut allergic subjects. CONCLUSION: In conclusion, cashew nut allergy is a significant tree nut allergy in Singapore.

Cashew nut allergy in Singaporean children

BACKGROUND: There has been an increasing trend of nut allergies in Singapore. OBJECTIVE: The aim of this study was to review the clinical characteristics of children with cashew nut allergy. METHODS: A retrospective analysis was conducted in a tertiary paediatric referral centre in Singapore from 2008 to 2015. A total of 99 subjects with positive specific IgE (≥0.35 IU/L) to cashew nut were identified. Clinical features including demographics, clinical reaction to cashew nut, associations with other nuts and test specific measurements were recorded. RESULTS: The results showed that cutaneous symptoms (71.2%) were the most common allergic manifestations. Anaphylaxis occurred in 3.8% of children. In addition, all cashew nut allergic subjects were cross-reactive (either sensitized or allergic) to pistachio. Cross-reactivity rate with peanuts was 53.8%. There was a strong prevalence of atopy among cashew nut allergic subjects. CONCLUSION: In conclusion, cashew nut allergy is a significant tree nut allergy in Singapore.

Low percentage of clinically relevant pistachio nut and mango co-sensitisation in cashew nut sensitised children.

BACKGROUND: Cashew nut, pistachio nut and mango belong to the Anacardiaceae family and are botanically related. Therefore, cashew nut sensitised children are frequently advised to eliminate cashew nuts and pistachio nuts from their diet. The 'Improvement of Diagnostic mEthods for ALlergy assessment (IDEAL trial number NTR3572) study showed that cashew nut sensitised children were co-sensitised to pistachio nut in 98% of cases and to mango in 21% of cases. The aim of this follow-up study to IDEAL is to assess the clinical relevance of co-sensitisation to pistachio nut and mango in cashew nut sensitised children. METHODS: Children were recruited from the study: 'Improvement of Diagnostic mEthods for ALlergy assessment (IDEAL trial number NTR3572). Inclusion criterion for the IDEAL study was sensitization to cashew nut as demonstrated by either SPT or sIgE, and a clinical history of reactions to cashew nuts or no previous (known) exposure. Sensitized children who were tolerant to cashew nuts were excluded. Inclusion criterion for this IDEAL follow-up study was co-sensitization to pistachio nut, regardless the result of the DBPCFC with cashew nut. In this follow-up study a double-blind placebo-controlled food challenge with pistachio nut and an open food challenge with mango were performed. RESULTS: Twenty-nine children (mean age of 11.6 years, 62% male) were included. Pistachio nut sensitisation was clinically relevant in only 34% of cashew-sensitised children and only 31% of cashew challenge positive children. None of the children was challenge positive to mango. CONCLUSION: Although co-sensitisation between cashew nut and pistachio nut was observed in 98%, pistachio nut sensitisation was only clinically relevant in 34% of the children. Therefore, a challenge test with pistachio nut is recommended in children with cashew nut and pistachio nut sensitisation. Trial registration The study was registered in the Dutch trial register (registration number 3572) on 10 August 2012 (retrospectively registered).

sIgE Ana o 1, 2 and 3 accurately distinguish tolerant from allergic children sensitized to cashew nuts.

BACKGROUND: The double-blind, placebo-controlled food challenge test (DBPCFC) is the gold standard in cashew nut allergy. This test is costly, time consuming and not without side effects. Analysis of IgE reactivity to cashew nut components may reduce the need for food challenge tests. METHODS: In a prospective and multicentre study, children with suspected cashew nut allergy underwent a DBPCFC with cashew nut. Specific IgE to cashew nut and to the components Ana o 1, 2 and 3 were determined. A skin prick test (SPT) with cashew nut extract was performed. The association between the outcome of the food challenge test and specific IgE to Ana o 1, 2 and 3 was assessed with logistic regression analyses, unadjusted and adjusted for other diagnostic variables. Discriminative ability was quantified with a concordance index (c). RESULTS: A total of 173 children (103 boys, 60%) with a median age of 9 years were included. About 79% had a positive challenge test outcome. A steep rise in the risk of a positive challenge was observed for specific IgE to each individual component Ana o 1, 2 and 3 with estimated risks up to approximately 100%. Median values of Ana o 1, 2, 3 were 1.29 kU/l (range 0-100 kU/l), 4.77 kU/l (range 0-100 kU/l) and 8.33 kU/l (range 0-100 kU/l) respectively and varied significantly (p < 0.001). Specific IgE to Ana o 1, 2 and 3 was better distinguished between cashew-allergic and tolerant children (c = 0.87, 0.85 and 0.89, respectively) than specific IgE to cashew nut or SPT (c = 0.76 and 0.83, respectively). CONCLUSION: The major cashew nut allergens Ana o 1, 2 and 3 are each individually predictive for the outcome of food challenge tests in cashew-allergic children.

No difference in health-related quality of life, after a food challenge with cashew nut in children participating in a clinical trial.

BACKGROUND: Previous studies showed that health-related quality of life (HRQL) significantly improved after the food challenge, with greater improvements in HRQL after a negative outcome than after a positive outcome. It is currently unknown whether this also occurs in patients undergoing DBPCFCs with cashew nut in the context of a clinical trial. METHODS: Quality of life was studied in children enrolled in a cashew nut study using Food Allergy Quality of Life Questionnaires (FAQLQs). Children, teenagers and parents of the children completed the questionnaires before the challenge test and 6 months after the DBPCFC with cashew nut. The difference in the change in HRQL between the children with a positive and negative DBPCFC outcome was studied by Mann-Whitney U-test. RESULTS: In total, 112 children (67 boys, median age of 9 years) were included. The children, teenagers and parents of the children completed 143 sets of questionnaires in total. There were no significant differences in baseline total and domain scores compared to the follow-up scores in the FAQLQ-CF, FAQLQ-TF and FAQLQ-PF. In children, the delta FAIM score in the negative DBPCFC tested group was significantly better than the delta FAIM score in the positive challenged group (p = 0.026). There were no significant differences in the changes in the scores of the FAQLQ-CF and FAQLQ-PF in the children with a positive challenge outcome, compared to the children with a negative challenge result. However, there was a significant difference in the change in score between the latter groups in the domain 'accidental exposure' of the FAQLQ-TF (p = 0.049). CONCLUSION: This study showed no difference in the change in HRQL scores after a DBPCFC with cashew nut in children participating in a clinical trial. The utility of HRQL as an outcome for clinical trials in food allergy may be limited if participant baseline HRQL is relatively unimpaired.

Particularities in a Child With Cashew Nut Allergy.

Food allergy affects many young children and tree nut allergy is accountable for a large number of severe, life-threatening anaphylactic reactions. Cross-reactivity can occur not only with foods that are in the same biological family but also between certain fruits or vegetables and latex (latex-fruit syndrome). We present the case of a previous healthy 5-year-old girl referred to Pediatric/Allergology Consultation after an episode of sialorrhea, perioral urticarial rash, tongue swelling, and immediate vomiting after oral contact with cashew nut. Investigation revealed the following: positive skin prick test to walnut and positive specific IgE for cashew nut, walnut, hazelnut, and almond. ImmunoCAP ISAC was positive for storage proteins of walnut and hazelnut (Jug r 1 e Cor a 9) and for a specific allergen of latex (Hev b 3). It is interesting that anaphylaxis was the first manifestation of allergy in a healthy child. Also, we emphasize the importance to latex sensitization with potential future clinical relevance and the sensitization to Hev b 3, which is not documented to be involved in cross-reactivity phenomena/latex-fruit syndrome or present in an otherwise healthy child.