Addressing Beta-lactam Allergy: A Time for actionElizabeth J. Phillips, MD, FIDSA, FAAAAI, Pascal Demoly, MD, PhD, Maria J Torres, MD, PhD1 Department of Medicine, Center for Drug Safety and Immunology, Vanderbilt University Medical Center, Nashville Tennessee USA, 2Institute for Immunology & Infectious Diseases, Murdoch University, Murdoch Australia, 3Division of Allergy, Department of Pulmonology, University Hospital of Montepellier, and IDESP, Univ. Montpellier – Inserm, Montpellier France,4Allergy Unit, Hospital Regional Universitario de Malaga-IBIMA-BIONAND-ARADyAL, and Departmento de Medicina, Universidad de Malaga, Malaga, SpainCorrespondence:Elizabeth J. Phillips, MD, FIDSA, FAAAAICenter for Drug Safety and ImmunologyVanderbilt University Medical Center1161 – 21st Avenue SouthNashville, TN 37232(615) 322-9174 (tel)[email protected] is now 93 years since the discovery of penicillins, and over 75 years since the first use of penicillin. We have entered yet another wave of challenges plagued with antibiotic resistance accelerating at a rate that well exceeds that of new antibiotic development. In the face of these uphill battles, 8-15% of a global population who has had access to care is labeled as penicillin allergic.1 In the United States (US) there are at maximum 6000 specialists who practice allergy out of a total of 700,000 practicing physicians, and not all allergists are proficient in and practice drug allergy. Conservatively out of 30,000,000 who are labeled as penicillin allergic at any one time in the US, this would mean that each allergist would need to delabel a minimum of 6000 patients. In Europe and the United Kingdom, the figures are proportionately identical, with some differences between countries. Even if all patients had equal access to care, this type of scalability remains impossible. This overwhelming burden that threatens to negatively impact healthcare through delays in treatment, higher healthcare utilization and cost, less effective treatment and increased antibiotic resistance and Clostridioides difficile infection, demands a risk-based approach that simplifies the penicillin allergy delabeling process and establishes bridges with non-allergists.1, 2What have we learned that now makes the population level goal of penicillin delabeling achievable? First off, prevention is better than cure. We should critically examine pediatric populations for antibiotic use to address over-prescription of antibiotics including penicillins for viral infections. We should avoid labeling children with benign delayed exanthems that occur in the setting of a likely viral infection as penicillin allergic. When continued treatment is necessary we should in fact encourage “treating through” such reactions. When a label of penicillin allergy seems inevitable in a child we should address this label early and pay particular attention to antibiotic stewardship. New data on serum sickness-like reaction suggests that many of these are likely virally mediated and do not reproduce on ingestion challenge.3 Community based education programs can help disseminate timely information on penicillin allergy to dispel myths and alleviate fears. A label of penicillin allergy should be both viewed and approached as a threat to both individual and public health. On a public health level addressing penicillin allergy should be seen as a broad stewardship tool that provides a level of herd protectiveness against antibiotic resistance. On an individual level a label of penicillin allergy should be approached with the same routineness as any other preventative health check, and primary care physicians and providers should be trained to understand and manage low-risk penicillin allergy labels.4 Patients should regularly discuss their drug allergy passport with their healthcare providers such as pharmacists and physicians. Allergy passports should enable interoperability, high traceability and time-stamped information solving the problem of frequent unavailability and inaccuracy of drug allergy information.5 Risk stratification should occur and if in a low-risk category a patient should be given the option of direct oral challenge and delabeling. Risk stratification to identify by clinical history the low-risk penicillin allergic patients who would be appropriate for simple procedures is key. Several mechanisms now exist to risk stratify those labeled as penicillin allergic in routine clinical practice. These clinical prediction rules provide an evidence base to identify the majority of low-risk penicillin allergy labeled patients who are at low risk for rechallenge reactions.6, 7 In current practice it is likely that less than 1% of such low-risk patients will be at risk for a reaction on ingestion challenge.1, 8To make widespread penicillin allergy delabeling an achievable and scalable goal we must be convinced of the safety of direct ingestion challenges. A randomized study allocated children 5 years or older with low-risk cutaneous reaction to penicillin skin testing followed by amoxicillin challenge versus 2 step direct oral challenge with amoxicillin with tolerance of amoxicillin of 96% of those with direct challenge and only minor reactions in the remainder.9These results have recently been confirmed in an European population of children.10 Aside from the inconvenience and potential need for specialty assessment, for very low-risk patients, the use of skin testing would be expected to perform poorly considering their low pre-test probability of a reaction. Several other studies have demonstrated that a single or two-step direct ingestion challenge with penicillins such as amoxicillin is a safe and practical strategy to remove a label of penicillin allergy.11 Although there is evidence to support the use of risk stratification tools to delabel penicillin allergy under allergist guidance, we require an educational program on drug allergy for primary care physicians as well validation of these risk stratification tools, to show that low-risk penicillin delabeling can be achieved in this setting.Even in the face of risk stratification and safety of direct ingestion challenge, populations are not equal in terms of their medical risk or antibiotic needs. Intuitively populations that serve to benefit from penicillins and other beta lactams have been shown to have inferior outcomes when labeled as penicillin allergic that would benefit from a delabeling intervention. This includes the association of penicillin allergy label and use of an alternative antibiotic with post-operative surgical site infections.12 Other settings where research has shown feasibility in delabeling include children in the emergency department, critically ill populations with high antibiotic needs, and pregnant women where the high rates of surgical delivery and group B Streptococcal colonization in pregnancy create a high demand for penicillin and cephalosporins as safe firstline drugs.1, 13, 14 Increasingly, assessment of unverified penicillin allergy has been recognized as an antibiotic stewardship intervention in immunocompromised states such as transplant and cancer where populations have much to gain by being delabeled.15There is a “time for action” for removal of penicillin allergy labels on a population level but how do we achieve widespread implementation (Figure 1)? Policy changes should be driven by collaboration with Infectious diseases specialists and allergists who should join forces to pair antibiotic allergy management with antibiotic stewardship. In the community we need to educate parents and pediatricians to make them aware of the hazards of both unnecessary antibiotics and penicillin allergy labels for mild rashes that are often related to a viral infection and unlikely to recur. Primary healthcare providers should be given greater incentives to delabel penicillin allergic patients at the point-of-care and armed with decision support tools to facilitate risk stratification. For those whose history is not consistent with allergy this could include direct delabeling without testing. In the future, evidence may support that routine direct ingestion challenge with a penicillin and delabeling is safe in the primary care setting. Finally, by off-loading low-risk reactions to primary care providers we can then prioritize care of the patients with a higher-risk allergy and/or medical history by engagement with specialists who can provide more in-depth assessments and give them the best antibiotic options.Figure 1: Addressing Beta-lactam Allergy: An Implementation Roadmap: There are currently many missed opportunities for community members and healthcare providers to take action forward on the “penicillin allergy delabeling” movement. This includes not only active measures to delabel patients by history and direct oral challenge and to identify high risk patients for prioritized penicillin allergy delabeling but also preventive measures to avoid unnecessary use and exposure to antibiotics and avoidance of unnecessary labeling in those with mild rashes of likely viral origin.

COVID-19 Vaccines Tolerated in Patients with Paclitaxel and Docetaxel Allergy

LETTER TO THE EDITORNo apparent impact of incremental dosing on eliciting dose at double-blind, placebo-controlled peanut challengeOlaya Álvarez García,1,2 Joan Bartra,1,3 Monica Ruiz-Garcia,1Isabel J. Skypala,1,4 Stephen R. Durham,1,4 Robert J. Boyle,1 E.N. Clare Mills,5 Paul J. Turner1

Access to the manuscript published in Allergy  https://doi.org/10.1111/all.15037

Background: Early exposure to allergens through a defect skin barrier has been proposed as a mechanism for inducing sensitization and development of allergic diseases. We hypothesized that early-onset, severe atopic dermatitis (AD) is associated with development of aeroallergen sensitization and allergic rhinitis. Methods: We included 368 children from the Copenhagen Prospective Studies on Asthma in Childhood 2000 (COPSAC 2000) at-risk mother-child cohort. AD was diagnosed prospectively based on Hanifin&Rajka’s criteria and severity assessed using the Scoring Atopic Dermatitis (SCORAD) index. Early-onset AD was defined as debut ≤1 year, late-onset as debut from 1-6 years. Aeroallergen sensitization and allergic rhinitis were diagnosed at ages 6-7 and 12 years. Associations between early-onset and late-onset AD and allergy endpoints were calculated using general estimating equations (GEE) models to compute the overall odds ratios (OR) for both time points. Results: Early-onset AD (yes/no) and severity (SCORAD) were associated with development of aeroallergen sensitization during childhood; GEE OR=1.68 [1.08; 2.62], p=0.02 and 1.08 [1.03; 1.12], p<0.001, whereas late-onset was not; GEE OR=1.65 [0.92; 2.94], p=0.08 and 1.01 [0.97; 1.06], p=0.55. The same trend was seen for allergic rhinitis with significant association between early-onset AD and allergic rhinitis; GEE OR=1.56 [1.01; 2.41], p=0.04 and severity; GEE OR=1.09 [1.05; 1.13], p<0.001, whereas late-onset AD showed no association. The effects on sensitization and rhinitis of early-onset vs. late-onset AD severity were significantly different: p-interaction sensitization=0.03 and p-interaction rhinitis<0.01. Conclusion: Increasing severity of early-onset AD, but not late-onset AD, associates with aeroallergen sensitization and allergic rhinitis later in childhood.

Progressive knowledge of allergenic structures resulted in a broad availability of allergenic molecules for diagnosis. Component resolved diagnosis allowed a better understanding of patient sensitization patterns, facilitating allergen immunotherapy decisions. In parallel to the discovery of allergenic molecules, there was a progressive development of a regulation framework that affected both in vitro diagnostics and Allergen Immunotherapy products. With a progressive understanding of underlying mechanisms associated to Allergen immunotherapy and an increasing experience of application of molecular diagnosis in daily life, we focus in analyzing the evidences of the value provided by molecular allergology in daily clinical practice, with a focus on Allergen Immunotherapy decissions.

Sweet syndrome induced by SARS-CoV-2 Pfizer-BioNTech mRNA vaccineAS Darrigade, MD1, H Théophile, MD2, P Sanchez-Pena, MD2, B Milpied, MD1, M Colbert4, MD, S Pedeboscq5, MD, T Pistone6, MD, ML Jullié, MD7, J Seneschal, MD, PhD1,31 : Department of Adult and Pediatric Dermatology, Bordeaux University Hospitals, France2 : Department of pharmacovigilancy, Bordeaux University Hospitals, France3 : Research Unit INSERM U10354 : Department of geriatry, Clinic Bordeaux Nord, Bordeaux, France5 : Department of pharmacology, Bordeaux University Hospitals, France6: Department of infectious disease, Bordeaux University Hospitals, France7: Department of anatomopathology, Bordeaux University Hospitals, FranceManuscript word count: 607Key words : sweet syndrome, SARS-CoV-2, Pfizer-BioNTech mRNA vaccine, delayed hypersensitivity, IDRCorresponding author: A.S. Darrigade, Dermatology Department, Saint-André Hospital, 1, rue Jean Burguet 33000 Bordeaux, FrancePhone: +33556794705Fax: [email protected] source: No financial disclosuresFinancial Disclosure: No external funding for this manuscriptTo the editor,A 45-year-old woman, without any past medical history or allergy presented in our clinic with a rapid onset of diffuse skin eruptions. Five days earlier, she received the first injection of the SARS-CoV-2 Pfizer-BioNTech mRNA. Concomitantly she took 1000mg paracetamol to prevent any post-vaccination syndrome. She well tolerated the preceding vaccines (influenza every year) before this one.The eruption started 24h after vaccine injection and was composed at time of the clinical exam of erythematous infiltrated papulosis located all over the body, without face involvement (Figure 1). No other extracutaneous symptoms were noted. Blood exams showed increased blood count levels with increased neutrophils count (8.77G/l), hepatic cytolysis (AST 67UI/L and ALT 116UI/l) with high level of PCR (115mg/l). SARS-CoV-2 PCR test and serology were negative. Viral tests for EBV, CMV, parvovirus B19, and Herpes simplex/Herpes zoster showed only a slight EBV reactivation. Histopathological examination of the skin biopsy showed a hyperplastic epidermis with an edematous papillary dermis. A superficial and deep dermal perivascular, periadnexal and interstitial dense infiltrate composed of neutrophils, eosinophils and lymphocytes was also a feature. Leukocytoclastic vasculitis was also seen (Figure 2A-2B). Clinical and pathological exams were compatible with the diagnosis of SS induced by SARS-CoV-2 Pfizer-BioNTech mRNA vaccine. Systemic steroid therapy (prednisone 0.5mg/kg/d) for five days was started and led to rapid improvement of the skin condition without any recurrence after treatment discontinuation. She did not receive the second vaccine injection.Patch-tests performed (14 days after steroid treatment stop, one month after SS) on both on healed and normal skin with pur SARS-CoV-2 Pfizer-BioNTech mRNA vaccine prepared less than 4 hours before were negative (Figure 1C 2-3). Then, intradermoreaction (IDR) with vaccine diluted at 1/10 on normal skin was positive in delayed reading (Figure 1C 1). Cutaneous biopsy was realized on the positive IDR reaction, showing an abundant inflammatory infiltrate predominantly with lymphocytes (Figure 2C).Cutaneous reactions after vaccine injection are rare, and heterogenous1. They could be related to the vaccine or the adjuvant. In addition, vaccine could trigger flares of chronic inflammatory conditions as it was previously reported1. At that time, minor local side effects are reported with SARS-CoV-2 vaccines such as pain, swelling or redness; hypersensitivity reactions were anaphylactic reaction but no severe delayed hypersensitivity are reported2-3. Three cases of acute febrile neutrophilic dermatosis are reported in the international bank of WHO, one in United Kingdom, one in United States of America and our case. Under SARS-CoV-2 Pfizer-BioNTech mRNA vaccine four cases of vasculitis had been reported after injection. In France one case of relapse of neutrophilic disorder was reported one day after SARS-CoV-2 Pfizer-BioNTech mRNA vaccine. The adjuvant associated with the SARS-CoV-2 Pfizer-BioNTech mRNA vaccine is polyethylene glycol (PEG) 20003. However our patient never received infusion containing PEG or polysorbate before. Patch-tests with PEG or polysorbate alone were not performed because of the negativity of the patch-test with the SARS-CoV-2 Pfizer-BioNTech mRNA vaccine. Only 10 cases of SS induced by vaccine are published so far including: 3 with seasonal influenza, 1 with influenza A, 2 with pneumococcal, 2 tuberculosis, 2 small pox4. SS is an acute inflammatory skin disease associated with important infiltration of neutrophils. Leukocytoclastic vasculitis could be present in SS5. One case of SS in a patient receiving pneumococcal vaccine showed the presence of dermal vasculitis associated with infiltration of neutrophils6. In case of anaphylactic reaction under SARS-CoV-2 Pfizer-BioNTech mRNA vaccine, the risk of relapse with the Moderna SARS-CoV-2 mRNA vaccine or SARS-CoV-2 vaccines with an adenovirus carrier and protein subunit remains unknown3, in case of SS even more.To conclude we report the first case of SS induce by SARS-CoV-2 Pfizer-BioNTech mRNA vaccine confirmed by positive IDR.

Article type: letter to the editor

Vaccines are essential public health tools with a favorable safety profile and prophylactic effectiveness that have historically played significant roles in reducing infectious disease burden in populations, when the majority of individuals are vaccinated. The COVID-19 vaccines are expected to have similar positive impacts on health across the globe. While serious allergic reactions to vaccines are rare, their underlying mechanisms and implications for clinical management should be considered to provide individuals with the safest care possible. In this review, we provide an overview of different types of allergic adverse reactions that can potentially occur after vaccination and individual vaccine components capable of causing the allergic adverse reactions. We present the incidence of allergic adverse reactions during clinical studies and through post-authorization and post-marketing surveillance and provide plausible causes of these reactions based on potential allergenic components present in several common vaccines. Additionally, we review implications for individual diagnosis and management and vaccine manufacturing overall. Finally, we suggest areas for future research.

Article type: News and Views: Groundbreaking Discoveries in ImmunologyTitle: Uncovering the influence of diet and gut microbiota in human serum metabolomeAuthors: David Obeso1,2‡, Elisa Zubeldia-Varela1,2‡ and Alma Villaseñor11Instituto de Medicina Molecular Aplicada (IMMA), Departamento de Ciencias Médicas Básicas. Facultad de Medicina. Universidad San Pablo-CEU, CEU Universities, Madrid, España.2Centro de Metabolómica y Bioanálisis (CEMBIO), Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, Madrid, España.‡: These Authors have equally contributedCorrespondence: Alma Villaseñor, Centro de Metabolómica y Bioanálisis (CEMBIO), Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, Madrid, EspañaEmail address:[email protected]: Metabolomics, Diet, Microbiota, Allergy, Serum, MetabolomeAbbreviations: MS, mass spectrometry; LC, liquid chromatography; short chain fatty acids (SCFA)Acknowledgement: We would like to thank Anna Głobińska for her assistance in generating the graphical figure. AV Gratefully acknowledges the Martín-Carbajo family for supporting her scientific development through the X Mario Martín Velamazán award.Author contributions: D.O., E.Z-V. and A.V contributed to the writing of the manuscript and have given approval to the manuscript. A.V. supervised the final version.

Letter to EditorTo the EditorEgg-allergic children have higher ovomucoid (OVM)-specific IgD (sIgD) levels compared to the atopic controls.1 Within the egg-allergic group, children with higher levels of OVM-sIgD have a decreased risk of anaphylactic reactions. Ovalbumin (OVA)-sIgD increases in egg-allergic children desensitized by oral immunotherapy (OIT) but not in children unresponsive to OIT or with sustained unresponsiveness to OVA challenge.2 The natural development of tolerance and the acquisition of sustained unresponsiveness by OIT in egg-allergic children are associated with an increase in OVM-specific IgG4 (sIgG4) levels and a decrease in OVM-specific IgE (sIgE) levels.3 To elucidate the potential role of IgD in the outgrowing of egg allergy, we analyzed levels of egg white (EW)-, OVM-, and OVA-sIgD and sIgG4 in sera from 57 egg-allergic children (28 avoided all forms of egg in the diet (complete avoidance of egg: CAE), 18 were able to ingest at least 1/32 cooked whole egg but not one cooked whole egg (partial avoidance of egg: PAE), and 11 outgrew egg allergy (OGE)) and 23 healthy non-egg allergic children (non-egg allergy: NEA) (Table S1). The study was approved by The Research Ethics Committee of University of Fukui (#20110052), and written informed consent was obtained from the parent or guardians.EW-, and OVM-sIgE levels measured using ImmunoCAP (Thermo-Fisher Inc., MA) were higher in the CAE group, followed by the PAE, OGE, and NEA groups (Fig 1, Fig S1). The CAE group exhibited lower serum levels of EW- and OVA-sIgD compared to the NEA group and the PAE group, respectively, and had the lowest OVM-sIgD serum levels among all groups, suggesting that OVM-sIgD levels are associated with outgrowing egg allergy. We observed the lowest serum levels of EW-, OVA-, and OVM-sIgG4 in the CAE group, followed by the PAE and OGE groups. The ratio of OVM-sIgD to OVA-sIgD increased as children outgrew egg allergy, whereas the ratio of OVM-sIgG4 to OVA-sIgG4 did not change. Thus, the production of OVM-sIgD differs from OVM-sIgG4 as children naturally outgrow egg allergy.High-affinity, but not low-affinity, IgE is known to cause anaphylaxis.4 High-affinity IgE is derived from memory IgG1+ B cells, whereas low-affinity IgE is derived from naïve IgM+IgD+ B cells. Considering class switching pathways, switching direction from IgM to IgD, and from IgG1 to IgE or IgG4, elevated OVM-sIgD levels might be associated with low-affinity OVM-sIgE levels as children outgrow egg allergy, resulting in hypo-responsiveness to OVM.A recent study found that OVM-sIgE avidity was more effective at differentiating clinically reactive egg-allergic patients from those tolerant of heated egg compared to EW-sIgE.5 The ratio of OVM-sIgE to OVM-sIgD or sIgG4 in the CAE group was significantly higher compared to the PAE, OGE, and NEA groups (Fig 2). Receiver operating analysis revealed that the ratio of OVM-sIgE to OVM-sIgD discriminated non-tolerant from partially-tolerant egg-allergic patients with the largest area under the curve (AUC = 0.965) compared with levels of OVM-sIgE or the ratio of OVM-sIgE to OVM-sIgG4. The optimal cutoff for the ratio of OVM-sIgE to OVM-sIgD had 86.5% sensitivity and 96.4% specificity to identify high-risk subjects (Table S2).There are several limitations to this study. First, there was a small number of patients. Second, all children were only challenged with heated egg and were instructed to avoid egg of any form if they tested positive with less than 1/32 cooked whole egg. Finally, there was a lack of trajectory of sIgD levels during natural tolerance development.In conclusion, the ratio of OVM-sIgE to OVM-sIgD is a useful marker to identify high-risk egg-allergic patients capable of ingesting a low-dose of cooked whole egg who might be a good candidate for low-dose OIT.

Background: Diagnostic tests for allergy rely on detecting allergen-specific IgE. Component-resolved diagnostics incorporate multiple defined allergen components to improve the quality of diagnosis and patient care. Objective: To develop a new approach for determining sensitization to specific allergen components that utilizes fluorescent protein tetramers for direct staining of IgE on blood basophils by flow cytometry. Methods: Recombinant forms of Lol_p_1 and Lol_p_5 proteins from ryegrass pollen (RGP) and Api_m_1 from honeybee venom (BV) were produced, biotinylated and tetramerized with streptavidin-fluorophore conjugates. Blood samples from 50 RGP-allergic, 41 BV-allergic and 26 controls were incubated with fluorescent protein tetramers for flow cytometric evaluation of basophil allergen binding and activation. Results: Allergen tetramers bound to and activated basophils from relevant allergic patients but not controls. Direct fluorescence staining of Api_m_1 and Lol_p_1 tetramers had greater positive predictive values than basophil activation for BV and RGP allergy, respectively, as defined with receiver operator characteristics (ROC) curves. Staining intensities of allergen tetramers correlated with allergen-specific IgE levels in serum. Inclusion of multiple allergens coupled with distinct fluorochromes in a single tube assay enabled rapid detection of sensitization to both Lol_p_1 and Lol_p_5 in RGP-allergic patients and discriminated between controls, BV-allergic and RGP-allergic patients. Conclusion: Our novel flow cytometric assay, termed CytoBas, enables rapid and reliable detection of clinically relevant allergic sensitization. The intensity of fluorescent allergen tetramer staining of basophils has a high positive predictive value for disease and the assay can be multiplexed for a component-resolved and differential diagnostic test for allergy.

Background Specific IgE against a peanut 2S albumin (Ara h2 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). Corresponding 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 h2 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 or tolerance upon hierarchical clustering of their Levenshtein distances. Conclusions HCDR3 sequence motifs associated with allergy or tolerance may support correct diagnosis of patients with suspected peanut allergy.

Background: Esophageal histology is critical for diagnosis and surveillance of disease activity in eosinophilic esophagitis (EoE). A validated noninvasive biomarker has not been identified. We aimed to determine the utility of blood and urine eosinophil-associated proteins to identify EoE diagnosis and predict esophageal eosinophilia. Methods: Blood and urine were collected from children undergoing endoscopy with biopsy. Absolute eosinophil count (AEC), plasma eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), major basic protein-1 (MBP-1), galectin-10 (CLC/GAL-10), Eotaxin-2 and Eotaxin-3, and urine osteopontin (OPN) and matrix metalloproteinase-9 (MMP-9) were determined. Differences were assessed between EoE and control, and with treatment response. The capacity to predict EoE diagnosis and esophageal eosinophil counts was assessed. Results: 183 specimens were collected from 56 EoE patients and 15 non-EoE patient controls; 33 EoE patients had paired pre- and post-treatment specimens. Plasma (CLC/GAL-10, ECP, EDN, Eotaxin-3, MBP-1) and urine (OPN) biomarkers were increased in EoE compared to control. A panel comprising CLC/GAL-10, Eotaxin-3, ECP, EDN, MBP-1, and AEC was superior to AEC alone in distinguishing EoE from control. AEC, CLC/GAL-10, ECP, and MBP-1 were significantly decreased in patients with a good response to treatment compared to patients with a poor response. AEC, CLC/GAL-10, ECP, EDN, OPN, and MBP-1 each predicted esophageal eosinophil counts utilizing mixed models controlled for age, gender, treatment and atopy; AEC combined with MBP-1 best predicted the counts. Conclusions: We identified novel panels of eosinophil-associated proteins that along with AEC are superior to AEC alone in distinguishing EoE from control and predicting esophageal eosinophil counts.

I thank Dres. Alnaes and Helnes Bergen for their stimulating comment on my medical algorithm on the Diagnosis and Treatment of Radiocontrast Media Hypersensitivity.1 In their comment, they raised attention to the possible addition of desensitization to radiocontrast media (RCM) management, which was not depicted in the algorithm.2 I have been well aware of several reports on desensitization and have already discussed them in a previous paper, however commented there that “successful desensitization of RCM has been reported for immediate hypersensitivity reactions to RCM, but it is only used anectodically” and concluded not to include this procedure into the algorithm.3In addition to the two papers on desensitization to RCM cited by Dr. Alaes, also a handful other cases have been published, some of them older. To my knowledge, at least as far as I can access these case reports, in none of these patients a proper allergy diagnosis and management has been performed and in most, if not all of these patients, desensitization probably was unnecessary. In the described cases, skin testing has not been performed or was even negative indicating a higher probability for a non-allergic immediate hypersensitivity reaction (IHR), in the history before desensitization was performed in several cases the RCM was not changed, but the same not tolerated RCM was given again and radiologists in vain relied on premedication to prevent recurrent attacks, and no skin test-negative RCM was identified and used. None of the cases published convinced me of the need for desensitization. Performing the examination with a skin test-negative RCM would with a high probability be successful.4 I would expect the success of desensitization was rather due to changing to a different isoosmolar RCM (and probably not to adding premedication) than the desensitization procedure itself, as alone changing the implicated RCM to another one in one study reduced the risk of recurrent IHR by 67.1% (odds ratio: 0.329; P = 0.001), whereas steroid premedication did not show protective effects.5Our group of European Network on Drug Allergy experts have highlighted that rapid desensitization is a procedure that can be used to provide a temporary tolerance to a first-line drug when no alternative is available.6 This implies for RCM hypersensitivity that using a skin-test-negative RCM for the next examination as an alternative drug is next step and not immediate desensitization. One problem with desensitization is that too many doctors employ it uncritically and without prior proper allergy workup, best with drug provocation test. The high rate of successful desensitizations without prior confirmation of drug hypersensitivity in the literature is in part explained by the fact that many of those patients would not have reacted anyway. I have yet to find convincing evidence to add desensitization as a standard therapeutic option to the RCM management algorithm.Having said this, I am eagerly following up the literature on RCM desensitization with great interest to be prepared, should I encounter an own patient, who would react severely to an alternative skin test-negative RCM after following the algorithm. Until now, colleagues and I have not met such a patient, however, I would seriously consider desensitization as an option in such a situation. Thus, I thank Dres. Alnaes and Helsen Bergen for bringing up that interesting topic for discussion.

In the newly published article: “Medical algorithm: Diagnosis and treatment of radiocontrast media hypersensitivity” K. Brockow [1], suggested an algorithm for the evaluation of hypersensitivity to radiocontrast media (RCM). However, one important aspect has been left out of the suggested algorithm, the opportunity to desensitize patients with probable or confirmed immediate hypersensitivity reactions to radiocontrast media.  Especially those reacting to more than one substance. Desensitization to allergens is a standard preventative measure of anaphylaxis when patients have a history of severe immediate hypersensitivity reactions to a drug, and there are no therapeutic alternatives [2]. Protocols for RCM desensitization are known from case reports [3,4], and need more work and research before standardized protocols can be recommended, but they can facilitate the use of radiocontrast media in important situations such as the need for acute coronary angiograms. Such situations are rare, but an algorithm should include information and pathways to facilitate the best treatment possible for all patients. Suggested change in the algorithm is to include the option “rapid desensitization” in the pathway “RCM urgently needed without test possibility and indispensable need for the RCM”, and in the pathway for ”patients with confirmed RCM hypersensitivity with immediate hypersensitivity reactions to several RCM’s for situations with indispensable need for RCM”. This would help to facilitate the best point of care for more patients with hypersensitivity to RCM. Dr. Alnæs has nothing to disclose. Dr Alnæs is the only contributor to this article.  1.     Knut Brockow, Medical algorithm: Diagnosis and treatment of radiocontrast media hypersensitivity Allergy 2020 ;75:1278-1280. doi: 10.1111/all.14147. 2.     P. Demoly  N. F. Adkinson  K. Brockow et al. International Consensus on drug allergy, Allergy 2014; 69: 420-437.  https://doi.org/10.1111/all.123503.     Mona Al-Ahmada and Tito Rodriguez Bouzab ,Successful desensitization to radiocontrast media in two high-risk cardiac patients. Ann Saudi Med. 2017; 37(4): 333–335. doi: 10.5144/0256-4947.2017.333 4.     Saurav Uppal , Anthony E DeCicco , Anselma Intini  et al. Rapid Desensitization to Overcome Contrast Allergy Prior to Urgent Coronary Angiography. Int Heart J  2018; 30; 59(3):622-625. doi: 10.1536/ihj.17-395.

Drug hypersensitivity reactions (DHRs) represent a global threat to healthcare systems due to their incidence, with a significant increase over last years1. DHR figures are overestimated in the general population since less than 40% of cases initially labelled as allergic can be confirmed as such when evaluated in an allergy unit2. Achieving an accurate diagnosis is complex and time consuming; besides, tests must be tailored to specific clinical manifestations and underlying mechanisms and will depend on the culprit drugs. Diagnosis often requires performing drug provocation tests (DPTs), which are especially problematic for severe reactions, making management of these patients challenging and expensive for the health care system.Clinically, DHRs are classified into immediate and non-immediate, based on the time interval between drug exposure and onset of the symptoms3. The most severe immediate reaction is anaphylaxis. This issue of the journal has been dedicated o drug hypersensitivity, which is becoming a major public health issue during the last decade, especially with the introduction of biologicals to medicine. Bilo et al. 4 evaluated the anaphylaxis mortality rate in Italy from 2004 to 2016 and found an average mortality rate for definite anaphylaxis (ICD-10 code) of 0.51 per million population per year, mostly due to the use of medications (73.7%), although in 98% of the cases culprit drugs were not identified. Regarding non-immediate reactions, one of the most challenging diagnoses is drug reaction with eosinophilia and systemic symptoms (DRESS), which is sometimes difficult, at an early stage, due to overlapping clinical symptoms with maculopapular exanthema (MPE). Pedruzzi et al. 5 identified 7 microRNAs (miRNAs) that correctly classified DRESS or MPE patients and were associated with keratinocyte differentiation/skin inflammation, type I IFN pathway viral replication, ATP-binding cassette transporters, and T lymphocyte polarisation, being all of them potential biomarkers. Non-immunologically mediated adverse reactions, such as attention-deficit/hyperactivity disorder (ADHD) are reported by Fuhrmannet al. 6 in association with systemic H1-antihistamines administration in school-age children, especially the 1st generation agents.The mechanism underlying DHR and the reason why patients treated with the same drug develop a tolerance response or an immediate or non-immediate DHR is not completely understood (Figure 1). Therefore, the prediction of who may experience a DHR, and if so, in what form, remains clinically obscure for most drugs. Goh SJR et al. 7 elegantly analyse this complexity, using non-immediate reactions to penicillins as a model. They focus on the understanding of the role of nature of the lesional T cells, the characterisation of drug-responsive T cells isolated from patient blood, and the potential mechanisms by which penicillins enter the antigen-processing and presentation pathway to stimulate these deleterious responses.Regarding specific drugs involved in allergy, betalactam antibiotics (BL) are the most frequent culprit, being many reactions mediated by IgE. This type of reaction varies among patients, with some reacting only to one BL and others to several of them; it tends to change over time and differs between European countries, depending on BL consumption. Nowadays, amoxicillin (AX), alone or in combination with the β-lactamase inhibitor clavulanic acid (CLV), is the most often prescribed BL worldwide (Figure 2) and the most common elicitor of reactions in both children and adults. It is unclear why patients after the administration of AX-CLV develop selective hypersensitivity to AX, while tolerating CLV and vice-versa. Ariza et al. 8 generated drug-specific T-cell clones from AX- or CLV-selective immediate hypersensitivity patients and found that both AX- and CLV-specific clones were generated irrespective of whether AX or CLV was the culprit, although a higher secretion of Th2 cytokines (IL-13 and IL-5) was detected when clones were activated with the culprit BL compared with clones stimulated with the tolerated BL, in which higher secretion of Th1 cytokines (IFN-γ) was observed. Regarding selective non-immediate reactions to CLV, Copaescu A et al. 9 report on a cohort of patients with a history of non-immediate reaction to CLV, who demonstrated a delayed intradermal skin test response to CLV, 17% were allergic to both CLV and ampicillin, and 83% were selective reactors with good tolerance to AX. IFN-γ release enzyme-linked immunospot (ELISpot) was performed giving a sensitivity of 33%. Other drugs such as sulphonamides, either antibiotic or non-antibiotics are important triggers of non-immediate DHRs. Vilchez-Sanchez et al. 10 showed that lymphocyte transformation tests (LTT) can help avoid the performance of DPT with a sensitivity of 75%, a specificity of 100%, and negative and positive predictive values of 72.7% and 100%, respectively.There has been a great expansion in the use of biological agents (mainly monoclonal antibodies (mAbs)), and they have greatly improved the treatment landscape of hemato-oncologic, autoimmune, inflammatory and rheumatologic diseases. In parallel, the incidence rate of reported DHRs associated with these products has increased considerably within the last years, ranging from mild to life-threatening. Yang BC et al. 11 recommend risk stratification as the first step for managing patients with DHRs to these drugs. In cases with negative skin test and mild reactions, DPT is an option, and in moderate or severe reactions, desensitisation becomes the preferred approach. In cases with positive skin test, desensitisation is the recommended course of action, especially when there is no alternative medication. Desensitisation is also widely used in the management of immediate hypersensitivity reactions to chemotherapy agents, such as platinums. There is suspicion about the presence of a longer memory of tolerance in subsequent desensitisation protocols partially resembling the regulatory tolerance mechanisms induced by allergen immunotherapy. Tüzer et al. 12 demonstrate the possible role of IL-10 in desensitisation with platinums, as they found a dynamic change in serum IL-10 levels observed as an increase during desensitisation and a decrease in between the protocols.Finally, a wide spectrum of drugs has been considered for treatment of coronavirus disease 2019 (COVID-19) and all of them can potentially induce DHRs. Gelincik A et al .13 reviewed DHRs in COVID-19 times to these drugs, with knowledge mainly coming from previous clinical experience in patients not infected with COVID-19. As in other viral infections, skin symptoms, including exanthemas, may appear during the evolution of the disease, leading to differential diagnosis with DHRs. Whether COVID-19 can aggravate T–cell mediated DHRs reactions as some viruses is at present unknown.We can conclude that new drugs are continuously introduced into the markets and confirmed as inducers of hypersensitivity reactions. We still do not completely understand the mechanisms underlying many of these reactions and further studies for improving diagnostic and management are needed even in classic and well-studied drugs as BLs.Abbreviations: AX: Amoxicillin; CLV: Clavulanic acid; COVID-19: Coronavirus disease 2019; DHR: Drug hypersensitivity reactions; DPT: Drug provocation tests; DRESS: Drug reaction with eosinophilia and systemic symptoms; ELISpot: enzyme-linked immunospot; LTT: Lymphocyte transformation tests; MPE: Maculopapular exanthema.

To the Editor, Immediate hypersensitivity reactions are related to mast cell and/or basophil activation. The mediators released such as tryptase and histamine are involved in clinical symptoms and are key parameters that contribute to diagnosis. Serum tryptase concentrations peak between 30 minutes and 4 hours following the reaction. Tryptase release is considered a robust marker of mast cell degranulation but is not informative in mild reactions.1 Histamine is released at the early beginning of the reaction but has a short half-life. The concentration value can be altered by pre-analytic conditions.2 Anaphylactic reactions can occur during night and week-end when laboratories can’t take charge of samples. To our knowledge, no thorough study of the stability in whole blood of these markers in anaphylaxis has been published. The aim of our study was to evaluate the impact of whole blood sample storage conditions (temperature and delay before centrifugation and plasma collection) on the reliability of tryptase and histamine measurements.Blood samples from 14 patients suspected of anaphylactic reactions (grade 2 to 4 of the Ring and Messmer scale)3 and from 10 volunteers were collected on EDTA after signed informed consent (CCPPRB Caen Basse-Normandie protocol 2004-32). The description of the patient anaphylactic episodes appears in Table 1.When received in the lab, an aliquot of whole blood was processed for diagnostic (reference measurement) and the remaining was divided in aliquots stored at room temperature (RT) or at +4°C for 24, 72 hours or 7 days (patients) or 2, 6, 24 or 72 hours for controls before centrifugation and plasma collection.Total tryptase concentrations were measured by an automated fluoroimmunoassay (ThermoFisher, Phadia SAS, ). Increased tryptase is defined as ≥ 1.2 x basal value + 2 µg.L-1.4 In our hands, tryptase uncertainties of measurement for low and high concentrations (9 µg.L-1 and 38.2 µg.L-1) are 17% and 16% respectively, in accordance with published results.5 Plasma histamine concentrations were measured by a radioimmunoassay (Beckman Coulter, Immunotech, France). Increased values defined by the manufacturer are >10 nmol.L-1, in accordance with published data.6 In our hands, histamine uncertainties of measurement for low and moderate concentrations (4.7 nmol.L-1 and 12.9 nmol.L-1) were 22% and 25%, respectively.The differences between the concentrations measured before and after storage were compared by paired two-tailed t-tests using SAS software. Results were considered significant for p < 0.05.As shown in Figure 1A, storage conditions did not modify tryptase concentrations (linear regression: slope=1.079, R²=0.9675). Tryptase concentrations appeared stable in whole blood left at +4°C for 7 days or 72 hours at RT.Histamine concentrations in patient samples were not modified during 72h at +4°C (Figure 1B) or at RT (Figure 1C). In the control group at RT, histamine concentrations were significantly increased at 6 hours (p=0.005) although moderately increased and staying within the limits of uncertainty measurement and never reaching the positivity threshold (Figure 1E). After 24 hours at RT a false positivity was observed for 8 of 10 samples (p<0.0001) (Figure 1E). At +4°C, histamine concentrations were significantly increased after 24 hours (p<0.0001) but remained in the limits of uncertainty measurement and under the threshold of positivity (Figure 1D). After 72h at +4°C, histamine concentrations exceeded the limits of uncertainty measurement and the positivity threshold for 4 samples of 10 (Figure 1D).Tryptase and histamine measurements are recommended to prove degranulation in anaphylaxis.7 Anaphylactic reactions occur unexpectedly. It is thus important to master sample shipment and processing before mediator measurement.The knowledge of possible artifacts modifying the measured values is necessary for the biochemist to address accreditation criteria of pre-analytic requirements (ISO 15189 standard) and for the physician to rely on trustable diagnostic data.Tryptase stability in whole blood had not been described. Our data has shown no impact on results after 72h at RT or 7 days at +4°C. Tryptase stability in plasma or serum has been evaluated by the manufacturer who ensured stability for 48h at RT or 5 days at +2°C to +8°C (Thermofisher).8 Thus, measured values of tryptase appear highly reliable.Histamine stability in whole blood had only been evaluated in controls and false positive results may be attributed to passive release from basophil during prolonged storage.2 We observed no impact for patient blood samples after 72h at +4°C or at RT. In contrast, false positive results were observed in controls after storage at RT during 24h or at +4°C during 72h. Histamine is known to be stable in the plasma obtained after centrifugation up to 4 days at RT for patients and controls.9According to these results, we suggest that whole blood samples can be stored at +4°C up to 72h for histamine and 7 days for tryptase when the laboratory is not available immediately. In any case, the biochemist must accept all these unrenewable samples. It is his role to take into account the pre-analytical conditions to interpret the results and provide helpful information to the physician.Keywords : pre-analytic; tryptase; histamine; whole blood.