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

IgE binding to peanut components by four different techniques: Ara h 2 is the most relevant in peanut allergic children and adults

Several studies have analysed the diagnostic value of specific IgE (sIgE) for individual peanut allergens. However, little is known about the concordance between different techniques available in both children and adults.To evaluate the value of individual peanut allergens by different techniques, i.e. multi-plexed microarray, single-plexed IgE assay, skin prick test (SPT) and immunoblot in both peanut allergic adults and children.Sensitization patterns to peanut allergens Ara h 1, 2, 3, and 8 were evaluated using four different techniques: multi-plexed microarray immunoassay, single-plexed IgE assay, SPT and immunoblot. Twenty-two peanut allergic adults and 15 children scored on clinical severity according to double-blind, placebo-controlled food challenges and 27 atopic control patients were included.Comparable sensitivity values were found between all four techniques in adults, with the highest sensitivity for Ara h 2 (76.2-95.5%, compared to 100% with all techniques in children). The multi-plexed assay to Ara h 1 (93.3%) demonstrated a higher sensitivity compared with the other three techniques (P = 0.04) in children, but absolute values were perfectly correlated. There were no differences between adults and children. The area under the receiver operating characteristic curve (AUC) of sIgE to Ara h 1 was higher with the multi-plexed assay compared with the single-plexed assay (0.91 vs. 0.75). In adults, sIgE to Ara h 1, 2, and 3 was correlated with clinical severity. No such correlation was found in children.In conclusion, the single- and multi-plexed assay, SPT and immunoblot perform equally in both peanut allergic adults and children, with Ara h 2 being most often recognized with all techniques. Specific IgE to Ara h 1, 2, and 3 in adults was correlated with severity.? 2013 John Wiley & Sons Ltd

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

The degree of whey hydrolysis does not uniformly affect in vitro basophil and T cell responses of cow's milk-allergic patients

BACKGROUND: Several studies investigated whether hydrolysed proteins can induce tolerance to cow's milk (CM) in children at risk of developing CM allergy. Due to methodological problems and inconsistent findings, the evidence for a tolerogenic effect is limited. A major problem is that different hydrolysates may give different outcomes due to variations in their production and composition. OBJECTIVE: The aim of the study was to investigate the effect of the degree of hydrolysis on the allergenicity and immunogenicity of whey hydrolysates. METHODS: The hydrolysis of whey was stopped at different time-points between 1 and 60 min. In 18 CM allergic patients, the allergenicity of the hydrolysates was determined by immunoblot and the basophil activation test. To test immunogenicity, CM-specific T cell lines were generated. RESULTS: In most patients, increasing time of hydrolysis decreased IgE recognition and basophil activation. However, in five patients, hydrolysed proteins induced more basophil activation than non-hydrolysed proteins. The immunoblot data indicated that these patients recognized either a 25- to 30-kDa degradation product of casein or a 10-kDa degradation product of whey. Although T cell activation was decreased in all patients over time, half of them still showed a positive response to the proteins after 60 min of hydrolysis. CONCLUSION: Increasing the time of hydrolysis reduces both allergenicity and immunogenicity of whey hydrolysates in most but not all patients. This indicates that not the degree of hydrolysis is decisive but the presence and stability of IgE and T cell epitopes in the hydrolysate recognized by individual patients

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

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

The degree of whey hydrolysis does not uniformly affect in vitro basophil and T cell responses of cow's milk-allergic patients

BACKGROUND: Several studies investigated whether hydrolysed proteins can induce tolerance to cow's milk (CM) in children at risk of developing CM allergy. Due to methodological problems and inconsistent findings, the evidence for a tolerogenic effect is limited. A major problem is that different hydrolysates may give different outcomes due to variations in their production and composition. OBJECTIVE: The aim of the study was to investigate the effect of the degree of hydrolysis on the allergenicity and immunogenicity of whey hydrolysates. METHODS: The hydrolysis of whey was stopped at different time-points between 1 and 60 min. In 18 CM allergic patients, the allergenicity of the hydrolysates was determined by immunoblot and the basophil activation test. To test immunogenicity, CM-specific T cell lines were generated. RESULTS: In most patients, increasing time of hydrolysis decreased IgE recognition and basophil activation. However, in five patients, hydrolysed proteins induced more basophil activation than non-hydrolysed proteins. The immunoblot data indicated that these patients recognized either a 25- to 30-kDa degradation product of casein or a 10-kDa degradation product of whey. Although T cell activation was decreased in all patients over time, half of them still showed a positive response to the proteins after 60 min of hydrolysis. CONCLUSION: Increasing the time of hydrolysis reduces both allergenicity and immunogenicity of whey hydrolysates in most but not all patients. This indicates that not the degree of hydrolysis is decisive but the presence and stability of IgE and T cell epitopes in the hydrolysate recognized by individual patients

Distinction between peanut allergy and tolerance by characterization of B​ cell receptor repertoires

BACKGROUND: Specific IgE against a peanut 2S albumin (Ara h 2 or 6) is the best predictor of clinically relevant peanut sensitization. However, sIgE levels of peanut allergic and those of peanut sensitized but tolerant patients partly overlap, highlighting the need for improved diagnostics to prevent incorrect diagnosis and consequently unnecessary food restrictions. Thus, we sought to explore differences in V(D)J gene transcripts coding for peanut 2S albumin‐specific monoclonal antibodies (mAbs) from allergic and sensitized but tolerant donors. METHODS: 2S albumin‐binding B‐cells were single‐cell sorted from peripheral blood of peanut allergic (n=6) and tolerant (n=6) donors sensitized to Ara h2 and/or 6 (≥ 0.1 kU/l) and non‐atopic controls (n=5). h 2 and/or 6 (≥ 0.1 kU/l). Corresponding h heavy and light chain gene transcripts were heterologously expressed as mAbs and tested for specificity to native Ara h2 and 6. HCDR3 sequence motifs were identified by Levenshtein distances and hierarchically clustering. RESULTS: The frequency of 2S albumin‐binding B cells was increased in allergic (median: 0.01%) compared to tolerant (median: 0.006%) and non‐atopic donors (median: 0.0015%, p = 0.008). The majority of mAbs (74%, 29/39) bound specifically to Ara h 2 and/or 6. Non‐specific mAbs (9/10) were mainly derived from non‐atopic controls. In allergic donors, 89% of heavy chain gene transcripts consisted of VH3 family genes, compared with only 54% in sensitized but tolerant and 63% of non‐atopic donors. Additionally, certain HCDR3 sequence motifs were associated with allergy (n = 4) or tolerance (n = 3) upon hierarchical clustering of their Levenshtein distances. CONCLUSIONS: Peanut allergy is associated with dominant VH3 family gene usage and certain public antibody sequences (HCDR3 motifs)