Our understanding of IgE-mediated drug allergy relies on the hapten concept, which is well established in inducing reactions of the immune system to small molecules like drugs. The role of hapten-carrier adducts in re-challenge reactions leading to mast cell degranulation and anaphylaxis is unclear. Based on clinical observations, the speed of adduct formation, skin and in-vitro tests to inert drug molecules, a different explanation of IgE-mediated reactions to drugs is proposed: These are a) A natural role of reduced mast cell (MC) reactivity in developing IgE-mediated reactions to drugs. This MC-unresponsiveness is antigen-specific and covers the serum drug concentrations, but allows reactivity to locally higher concentrations. b) Some non-covalent drug-protein complexes rely on rather affine bindings and have a similar appearance as covalent hapten-carrier adducts. Such drug-protein complexes represent so-called “fake antigens”, as they are unable to induce immunity, but may react with and crosslink preformed drug-specific IgE. As they are formed very rapidly and in high concentrations, they may cause fulminant MC degranulation and anaphylaxis. c) The generation of covalent hapten-protein adducts requires hours, either because the formation of covalent bonds requires time or because first a metabolic step for forming a reactive metabolite is required. This slow process of stable adduct formation has the advantage that it may give time to desensitize mast cells, even in already sensitized individuals. The consequences of this new interpretation of IgE mediated reactions to drugs are potentially wide-reaching for IgE-mediated drug allergy but also allergy in general.

The pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has made widespread impact recently. We aim to investigate the clinical characteristics of COVID-19 children with different severities and allergic status. Pediatric COVID-19 patients tended to have a mild clinical course. Patients with pneumonia had higher proportion of fever and cough and increased inflammatory biomarkers than those without pneumonia. There was no difference between allergic and non-allergic COVID-19 children in aspects of incidence, clinical features, laboratory and immunological findings. Allergy was not a risk factor for developing and severity of SARS-CoV-2 infection and hardly influenced the disease course of COVID-19 in children.

Background: Although the importance of ectopic lymphoid tissues (eLTs) in the pathophysiology of nasal polyps (NPs) is increasingly appreciated, the mechanisms underlying their formation remain unclear. Objective: To study the role of IL-17A, CXCL13 and lymphotoxin (LT) in eLT formation in NPs. Methods: The expression of CXCL13 and LT as well as their receptors, and the phenotypes of stromal cells in NPs were studied by flow cytometry, immunostaining, and RT-PCR. Purified nasal stromal cells and polyp B cells were cultured and a murine model with nasal type 17 inflammation was established for the mechanistic study. Results: Excessive CXCL13 production was found in NPs and correlated with enhanced IL-17A expression. Stromal cells, with an expansion of CD31-Pdpn+ fibroblastic reticular cell (FRC) type, were the major source of CXCL13 in NPs without eLTs. IL-17A induced FRC expansion and CXCL13 production in nasal stromal cells. In contrast, B cells were the main source of CXCL13 and LTα1β2 in NPs with eLTs. CXCL13 upregulated LTα1β2 expression on polyp B cells, which in turn promoted CXCL13 production from polyp B cells and nasal stromal cells. LTα1β2 induced expansion of FRCs and CD31+Pdpn+ lymphoid endothelial cells, corresponding to the phenotypic characteristic of stromal cells in NPs with eLTs. IL-17A gene knockout, and CXCL13 and LTβR blockage diminished nasal eLT formation in the murine model. Conclusion: We identified an important role of IL-17A-induced stromal cell remodeling in the initiation, and crosstalk between B and stromal cells via CXCL13 and LTα1β2 in the enlargement of eLTs in NPs.

Coronavirus disease 2019 (COVID-19), a respiratory tract infection caused by a novel human coronavirus, the severe acute respiratory syndrome coronavirus 2, leads to a wide spectrum of clinical manifestations ranging from asymptomatic cases to patients with mild and severe symptoms, with or without pneumonia. Given the huge influence caused by the overwhelming COVID-19 pandemic affecting over three million people worldwide, a wide spectrum of drugs is considered for the treatment in the concept of repurposing and off-label use. There is no knowledge about the diagnosis and clinical management of the drug hypersensitivity reactions that can potentially occur during the disease. This review brings together all the published information about the diagnosis and management of drug hypersensitivity reactions due to current and candidate off-label drugs and highlights relevant recommendations. Furthermore, it gathers all the dermatologic manifestations reported during the disease for guiding the clinicians to establish a better differential diagnosis of drug hypersensitivity reactions in the course of the disease.

Title: Real-life study in non-atopic severe asthma patients achieving disease control by omalizumab treatmentTo the Editor,Severe asthma is defined as asthma requiring treatment with guidelines-suggested medications for Global Initiative for Asthma (GINA) steps 4 or 5 or systemic corticosteroids for ≥50% of the previous year to prevent it from becoming ‘uncontrolled’ or which remains ‘uncontrolled’ despite this therapy.1 Up to 34%–50% of severe asthmatic patients have non-atopic (also called non-allergic) asthma. 2 A significant proportion of these patients have severe uncontrolled asthma, which requires high doses of inhaled corticosteroids (ICS) or even oral corticosteroids (OCS).2 Until the advent of biologics, treatment options in these patients have been very limited. For many years, both the pathogenesis knowledge and the results of clinical trials supported the view that anti-IgE treatment is specifically effective in allergic asthma. Interestingly, recent molecular and clinical evidence suggests that anti-IgE treatment might also be effective in patients with non-allergic asthma.2 Omalizumab (Xolair®) is an anti-IgE monoclonal antibody that selectively binds to human IgE and prevents the binding of IgE to its receptors. Although omalizumab is indicated in Europe in patients with severe persistent allergic asthma, several case reports and short series have provided data on the value of omalizumab in patients with non-atopic asthma.3,4The observational, multicenter, retrospective, real-life FENOMA study specifically evaluated patients who achieved full asthma control after one year of treatment with omalizumab.5 The study included 345 patients, 80 (23.2%) of whom had non-atopic asthma. The present post-hoc sub-analysis aims to describe the clinical improvement of patients with non-atopic asthma. Socio-demographic and asthma-related characteristics were collected at baseline. Outcomes analyzed at baseline and after one year of treatment were those included in the definition of asthma control by GEMA guidelines.5 Medical records were reviewed between February 2015 and June 2016. For statistical comparisons, the 2-sided Wilcoxon signed-rank test was used. A P-value of <0.05 was considered to be statistically significant. All analyses were performed with the SAS statistical package (version 9.4; SAS Institute, Cary, NC).The primary outcome of this post-hoc sub-analysis was to describe the baseline characteristics and clinical improvement of non-atopic asthma patients who achieved full disease control after one-year of treatment with omalizumab through i) frequency of daytime symptoms, ii) changes in use of ICS or OCS iii) need for rescue therapy, iv) pulmonary function (forced expiratory volume in 1 second [FEV1]), v) number of non-severe exacerbations and vi) use of healthcare resources, i.e. unplanned visits to primary care or specialists and the number of days of school or workplace absenteeism due to asthma worsening. Non-severe asthma exacerbations were defined as those that did not require OCS, emergency assistance or hospitalization. Secondary outcomes include an assessment of the percentage of eosinophil blood count and exhaled nitric oxide fraction (FeNO) before and after treatment.Demographic, clinical characteristics and asthma history (before starting treatment with omalizumab) are shown in Table 1 . Mean (SD) age of patients was 58.7 (12.2) years and 65% were female. Almost all patients had daytime symptoms, 92% of patients needed rescue medication, and the mean (SD) initial dose of omalizumab was 338.7 (153.1) mg.After one year of treatment with omalizumab 50.0% (n=40) of patients had no daytime symptoms, while 37.5% (n=30) and 12.5% (n=10) had symptoms 1 and 2 days per week, respectively. Forty-one (51.2%) of the 54 patients who were receiving OCS at entry, stopped treatment (P<0.0001). Of those continuing on OCS, the average reduction of the daily dose was not statistically significant (P=0.2132). More than half of patients (53.7%, n=43) needed no rescue medication. Median FEV1 increase was 15% and there was a reduction in the number of non-severe asthma exacerbations. After one year of treatment with omalizumab, a great reduction in unplanned visits and absenteeism from school or workplace (P<0.0001; Table 2 ) was observed.Of note, the effectiveness of omalizumab was previously assessed in a Spanish multicenter registry, which evaluated 29 non-atopic severe asthma patients over 2 years.6 However, our series is the most extensive study in patients with non-atopic asthma published to date in Spain, and provides data on full disease control. There have been several potential suggestions to explain the effectiveness of omalizumab in non-atopic patients.7 In a proof-of-concept study in non-atopic asthma patients, treatment with omalizumab resulted – as per in atopic patients – in a significant reduction of high-affinity IgE receptor (FcεRI) expression on blood basophils and plasmacytoid dendritic cells (pDC2), which hampered IgE binding and the subsequent production on proinflammatory mediators.8 Additionally, omalizumab treatment was associated with an increase in FEV1 with a positive trend in some relevant clinical endpoints, such as asthma exacerbations.8 In another proof-of-concept trial, omalizumab therapy (but not placebo) reduced IgE expression and IgE sensitization of target cells within the bronchial mucosa, and increased FEV1 versus baseline despite withdrawal of conventional therapy.9 Interestingly, it has been hypothesized that patients labelled as ‘non-allergic’ might in fact have a localized allergy to an unrecognized allergen, with elevated concentrations of allergen-specific IgE antibodies in the airways.7Our study has several limitations. Its single-arm retrospective nature relies on the accuracy and completeness of the information entered into the clinical records. This has especially affected predictors of response such as FeNO and the level of eosinophils, which were not routinely assessed in the clinical practice at the time of the study. The benefits of omalizumab presented here are those observed in the population of non-atopic patients who achieved disease control after one year of treatment with omalizumab. It is unknown how many other patients classified as non-atopic in the clinical practice did not benefit from this treatment.In summary, in the population of patients with non-atopic severe asthma who achieved full disease control after one year of treatment with omalizumab, the clinical and pulmonary benefits were remarkable and similar to those described for atopic patients. A reduction in the use of healthcare resources was also documented. Large randomized controlled trials are warranted to confirm the value of omalizumab in this population of patients.

COVID-19 Clinical trials: quality matters more than quantity