Beta-lactam-induced immediate hypersensitivity reactions: A genome-wide association study of a deeply phenotyped cohort.

BACKGROUND: ß-lactam antibiotics are associated with a variety of immune-mediated or hypersensitivity reactions, including immediate (type I) reactions mediated by antigen-specific IgE. OBJECTIVE: We sought to identify genetic predisposing factors for immediate reactions to ß-lactam antibiotics. METHODS: Patients with a clinical history of immediate hypersensitivity reactions to either penicillins or cephalosporins, which were immunologically confirmed, were recruited from allergy clinics. A genome-wide association study was conducted on 662 patients (the discovery cohort) with a diagnosis of immediate hypersensitivity and the main finding was replicated in a cohort of 98 Spanish cases, recruited using the same diagnostic criteria as the discovery cohort. RESULTS: Genome-wide association study identified rs71542416 within the Class II HLA region as the top hit (P = 2 × 10-14); this was in linkage disequilibrium with HLA-DRB1∗10:01 (odds ratio, 2.93; P = 5.4 × 10-7) and HLA-DQA1∗01:05 (odds ratio, 2.93, P = 5.4 × 10-7). Haplotype analysis identified that HLA-DRB1∗10:01 was a risk factor even without the HLA-DQA1∗01:05 allele. The association with HLA-DRB1∗10:01 was replicated in another cohort, with the meta-analysis of the discovery and replication cohorts showing that HLA-DRB1∗10:01 increased the risk of immediate hypersensitivity at a genome-wide level (odds ratio, 2.96; P = 4.1 × 10-9). No association with HLA-DRB1∗10:01 was identified in 268 patients with delayed hypersensitivity reactions to ß-lactams. CONCLUSIONS: HLA-DRB1∗10:01 predisposed to immediate hypersensitivity reactions to penicillins. Further work to identify other predisposing HLA and non-HLA loci is required.

Detection of Serum-Specific IgE by Fluoro-Enzyme Immunoassay for Diagnosing Type I Hypersensitivity Reactions to Penicillins.

Diagnosis of type I hypersensitivity reactions (IgE-mediated reactions) to penicillins is based on clinical history, skin tests (STs), and drug provocation tests (DPTs). Among in vitro complementary tests, the fluoro-enzyme immunoassay (FEIA) ImmunoCAP® (Thermo-Fisher, Waltham, MA, USA) is the most widely used commercial method for detecting drug-specific IgE (sIgE). In this study, we aimed to analyze the utility of ImmunoCAP® for detecting sIgE to penicillin G (PG) and amoxicillin (AX) in patients with confirmed penicillin allergy. The study includes 139 and 250 patients evaluated in Spain and Italy, respectively. All had experienced type I hypersensitivity reactions to penicillins confirmed by positive STs. Additionally, selective or cross-reactive reactions were confirmed by DPTs in a subgroup of patients for further analysis. Positive ImmunoCAP® results were 39.6% for PG and/or AX in Spanish subjects and 52.4% in Italian subjects. When only PG or AX sIgE where analyzed, the percentages were 15.1% and 30.4%, respectively, in Spanish patients; and 38.9% and 46% in Italian ones. The analysis of positive STs showed a statistically significant higher percentage of positive STs to PG determinants in Italian patients. False-positive results to PG (16%) were detected in selective AX patients with confirmed PG tolerance. Low and variable sensitivity values observed in a well-defined population with confirmed allergy diagnosis, as well as false-positive results to PG, suggest that ImmunoCAP® is a diagnostic tool with relevant limitations in the evaluation of subjects with type I hypersensitivity reactions to penicillins.

A well-tolerated new amino acid-based formula for cow's milk allergy.

OBJECTIVES: Infants with cow's milk allergy (CMA) are in need of a substitute formula up to 2 years. The are three requisites for a substitute of milk in CMA: tolerability, nutritional adequacy, and cost-effectiveness. We evaluate here the tolerability of a new amino acid-based infant formula for the management of CMA. METHODS: In a phase III/IV prospective, multicentre, open-label, international study, infants and children with immunoglobulin E-mediated CMA were exposed to a diagnostic double-blinded, placebo-controlled food challenge with a new amino acid formula by Blemil Plus Elemental using Neocate as the placebo. If tolerant to it, the study formula was integrated into the patients' usual daily diet for 7 days. Efficacy on day 7 was assessed in terms of symptoms associated with CMA, amount of formula consumed, nutritional and energy intake, and anthropometric data. RESULTS: Thirty children (17 M and 13 F; median age, 1.58; range, 0.08-12.83 years) completed the open challenge and were able to consume the study formula for at least 7 days. No signs or symptoms of allergic reactions were recorded among children assuming either the test or the control formula, with a lower 95% one-sided confidence interval for the proportion of subjects who did not experience allergic reactions above 90%. Sixteen patient under the age of two continued with the optional extension phase. CONCLUSIONS: The study formula meets the American Academy of Pediatric criteria for hypoallergenicity and is well tolerated in short-term use. During optional phase, growth of the patients was not hindered by the study formula.

A Multicenter Retrospective Study on Hypersensitivity Reactions to Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) in Children: A Report from the European Network on Drug Allergy (ENDA) Group.

BACKGROUND: Diagnosis of hypersensitivity (HS) reactions to nonsteroidal anti-inflammatory drugs (NSAIDs) in children is complex. The real prevalence of NSAID HS remains unknown because a drug provocation test (DPT) is not always performed with the culprit NSAID. OBJECTIVE: To describe and compare the diagnostic workup among different European centers and to find out the real proportion of NSAID HS by performing a DPT with the culprit drug. METHODS: We retrospectively collected data from children (0-10 years) and adolescents (10-18 years) with a history of NSAID reactions and who underwent a complete allergy workup including DPTs with the culprit in 6 different pediatric centers: Belgrade, Florence, Geneva, Madrid, Porto, and Rome. RESULTS: A total of 693 children with a history of NSAID reactions were enrolled, and a total of 526 DPTs were performed with the culprit NSAID. The diagnosis of NSAID HS was confirmed in 19.6% (103 of 526) of children by performing a DPT with the culprit drug. The major differences in the allergy workup among the 6 centers concerned the duration of the DPT and the practical use of skin tests for diagnosing NSAID HS. In addition, the use of acetyl salicylic acid to differentiate single reactor or cross-intolerance patients is not common, except in Spain. CONCLUSION: The value of this study is that although different approaches are used around Europe to diagnose NSAID HS, we found that the percentage of confirmed NSAID HS is less than 20%. This highlights the importance of the DPT in confirming or excluding NSAID HS in the pediatric population.

Use of biologics in severe food allergies.

PURPOSE OF REVIEW: Severe cases of food allergy account for the majority of the burden in terms of risks, quality of life, and resource expenditure. The traditional approach to these forms has been strict avoidance. More recently, Oral ImmunoTherapy (OIT) has gained a role in their management. However, in severe food allergies OIT is often infeasible. RECENT FINDINGS: Case reports, observational, and prospective studies have recently proposed different approaches to severe food allergy. The majority of them include the use of biologics. Omalizumab has been the most studied drug for severe food allergies, and its role as adjuvant treatment to OIT is well established. Interest has been raised on other biologics, as dupilumab, reslizumab, and mepolizumab. Toll-like receptor agonists, and gene therapy using adeno-associated virus coding for Omalizumab are promising alternatives. SUMMARY: The recent studies are deeply influencing the clinical practice. We review the modifications of the clinical approach to severe food allergies so far available. We indicate the possible evolutions of treatment with biologics in severe food allergies.