Nonallergic drug hypersensitivity reactions

Amphotericin B for injection triggers degranulation of human LAD2 mast cells by MRGPRX2 and pseudo-allergic reactions in mice via MRGPRB2 activation

Amphotericin B, a polyene macrolide antifungal agent, still plays an important role in the management of serious systemic fungal infections. Amphotericin B deoxycholate (AmBd) has been used to treat invasive fungal infections for over 60 years and remains the primary clinical formulation currently available. Anaphylactoid reactions triggered by AmBd in the clinic have been documented. However, the molecular and cellular events contributing to these reactions have not been clearly elucidated to date. This study demonstrates that the human Mas-related G protein-coupled receptor X2 (MRGPRX2) is the receptor that mediates these anaphylactoid responses. Molecular docking and cellular thermal shift assay (CETSA) indicate that AmBd exhibits potential affinity with MRGPRX2. In vitro, exposure to AmBd results in significant release of LAD2 mast cell granules and induces intracellular Ca2+ mobilization as well as activation of PLC-γ/IP3R and PI3K/AKT signaling pathways. However, these phenomena are reduced in MRGPRX2-knockdown LAD2 cells. In vivo, AmBd triggers paw swelling and a rapid drop in core body temperature in wild-type (WT) mice. However, these reactions are almost absent in MRGPRB2 (the mouse homolog of MRGPRX2) knockout mice (MRGPRB2MUT, MUT). The above results suggest that AmBd activates PLC-γ/IP3R and PI3K/AKT signaling via MRGPRX2 (in human LAD2 mast cells) or MRGPRB2 (in mice), leading to the release of mast cell granules and subsequent triggering of pseudo-allergic reactions. Taken together, this study clarifies the role of MRGPRX2 in triggering pseudo-allergic reactions to AmBd and suggests that MRGPRX2 could be a potential therapeutic target for controlling these reactions.

Ibuprofen and Other Arylpropionics: The Relevance in Immediate Hypersensitivity Drug Reactions

BACKGROUND

Ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), is the most frequent medication to be involved in hypersensitivity drug reactions (HDRs). Other analgesic/anti-inflammatory drugs in the arylpropionic group are also relevant, albeit to a lesser extent. Ibuprofen is widely consumed by people of all ages, both on medical prescription and over the counter; moreover, it is an organic contaminant of surface waters and foods. While numerous drugs cause HDR, ibuprofen's underlying mechanisms are more intricate and involve both specific immunological and non-immunological mediated reactions.

SUMMARY

we concentrate on immediate responses, including urticaria with or without angioedema, anaphylaxis, and angioedema, classifying reactions according to whether they are caused by single or multiple NSAIDs and based on the mechanisms at play. Both groups may experience anaphylaxis, defined as an immediate, severe systemic reaction involving at least two organs, though the frequency and severity can vary. Following this classification, more clinical manifestations can be identified. Diagnosis is partly based on a detailed clinical history, including information about ibuprofen and/or other arylpropionic derivatives involved, the interval between drug intake and symptoms onset, clinical manifestations, number of episodes, and the patient's tolerance or response to other medications - mainly non-chemically related NSAID - both before and after reactions to ibuprofen and/or other arylpropionic drugs. A drug provocation test is frequently necessary to make a diagnosis.

KEY MESSAGE

Because ibuprofen is the most widely prescribed NSAID, it is reasonable to assume its role as the leading cause of HDR will only become more important.

Drug-induced hypersensitivity reactions in a Lebanese outpatient population: A decade-long retrospective analysis (2012-2021)

Background

Drug hypersensitivity reactions (DHRs) are becoming more common as a result of increasing prevalence and case complexity. Allergists and clinical immunologists worldwide are challenged daily to adequately diagnose and manage these reactions. Data in the literature regarding DHR outpatient consultations are scarce worldwide, limited in the Middle East, and currently unavailable in Lebanon.

Objective

This retrospective study aimed to evaluate the characteristics of all reported DHRs over 10 years in a tertiary-care allergy clinic in Lebanon.

Methods

We conducted a decade-long (2012-21) retrospective analysis of the archived medical records of patients with a history of DHRs. Demographics, clinical history, diagnostic tools, and characteristics of the DHRs were collected and analyzed.

Results

A total of 758 patients experienced DHRs to therapeutic molecules provided for ambulatory care. Our results identified 72 medications. The most frequently implicated drug classes included β-lactam antibiotics (53.8%), followed closely by nonsteroidal anti-inflammatory drugs (48.9%). Of the 758 patients, 32.6% reported DHRs to multiple molecules, and 11.8% reported concomitant DHRs to 1 or several molecules provided in the perioperative setting. Of those, opioids and neuromuscular blocking agents were the 2 most common therapeutic classes. Furthermore, we evaluated the cross-reactivity between molecules of the same class. In neuromuscular blocking agents, rocuronium and cisatracurium were the most commonly cross-reactive, and for opioids, the most common association we recorded was with morphine and pethidine.

Conclusion

Our findings constitute the first step toward a more comprehensive evaluation of the clinical characteristics of DHRs in Lebanon.

Dl-3-n-butylphthalide induced anaphylactic shock: a case report

Dl-3-n-butylphthalide (DL-NBP) has good neuroprotective function and is safe for use in patients with acute ischaemic stroke. DL-NBP induced anaphylactic shock is rarely reported. Here we describe the case of a 75-year-old woman who received an injection of DL-NBP (25 mg/100 mL intravenously guttae, twice daily) for acute ischaemic stroke. Approximately 5 min after the DL-NBP injection was administered, the patient developed a decrease in blood pressure and an increase in heart rate along with skin pruritus, mottlement of the lower limbs, discomfort, and the desire to defecate, following which DL-NBP was discontinued immediately. The patient recovered with antiallergic therapy and could tolerate further treatment. We emphasise that the increased use of DL-NBP in recent year raises the importance of attention to potential allergies in clinical use, especially in patients with a history of allergies to multiple drugs.

Anaphylactoid reactions induced by Shuanghuanglian injection and Shenmai injection and metabolomics analysis

Introduction: Shuanghuanglian injection (lyophilized) (SHLI) is commonly used to treat respiratory tract infection. Shenmai injection (SMI) is mainly used to treat cardiovascular diseases. Despite their widespread clinical use, anaphylactoid reactions (ARs) induced by SHLI and SMI have been reported, which have attracted broad attention. However, the impact of ARs on metabolic changes and the underlying mechanisms are still unclear. Methods: ICR mice were used as model animals and were treated with normal saline, C48/80, SHLI and SMI, respectively. The behavior of mice, auricle blue staining and Evans Blue exudation were used as indexes to evaluate the sensitization of SHLI and SMI and determine the optimal sensitization dose. Anaphylactoid mice model was established based on the optimal dose and enzyme-linked immunosorbent assay (ELISA) was used to model verification. Afterwards, plasma samples of administered mice were profiled by LC-MS metabolomics and analyzed to evaluate the changes in metabolites. Results: High doses of both SHLI and SMI can induce severe anaphylactoid reactions while the reaction induced by SMI was weaker. A Partial Least-Squares Discriminant Analysis (PLS-DA) score plot indicated that following administration, significant metabolic changes occurred in mice. 23 distinct metabolites, including deoxycholic acid, histamine, and 5-hydroxytryptophan, were identified in the SHLI groups. 11 distinct metabolites, including androsterone, 17α-hydroxypregnenolone, and 5-hydroxyindoleacetate, were identified in the SMI groups. Meanwhile, different metabolic pathways of SHLI and SMI were predicted by different metabolites. The associated metabolic pathways include steroid hormone biosynthesis, tryptophan metabolism, histidine metabolism, arachidonic acid metabolism, nicotinate and nicotinamide metabolism, and primary bile acid biosynthesis. Conclusion: Study showed that both SHLI and SMI can induce varying degrees of anaphylactoid reactions, a positive correlation between response intensity and dose was observed. Metabolomics showed that SHLI and SMI may promote the simultaneous release of hormones and inflammatory factors by disturbing relevant metabolic pathways, while SMI may also inhibit the release of inflammatory factors in arachidonic acid metabolic pathway, indicating both pro-inflammatory and anti-inflammatory effects. This study will serve as a reference for developing a new approach to evaluate the safety of SHLI and SMI from perspective of susceptible drug varieties. However, ARs mechanism requires further verification.

[Principles of allergy diagnostics]

BACKGROUND

Allergies are frequent and approximately 30% of the general population in Germany are affected. The specific sensitization against an allergen is asymptomatic. On renewed allergen contact the symptoms are indicative of the underlying pathomechanism. A variety of different test procedures are available to identify allergic reactions.

OBJECTIVE AND AIM

In this review article the typical clinical symptoms of allergic reactions are assigned to mechanisms and possible test methods are presented and discussed. Current developments in recombinant serum diagnostics and cellular testing methods are presented.

Hypersensitivity reactions to small molecule drugs

Drug hypersensitivity reactions induced by small molecule drugs encompass a broad spectrum of adverse drug reactions with heterogeneous clinical presentations and mechanisms. These reactions are classified into allergic drug hypersensitivity reactions and non-allergic drug hypersensitivity reactions. At present, the hapten theory, pharmacological interaction with immune receptors (p-i) concept, altered peptide repertoire model, and altered T-cell receptor (TCR) repertoire model have been proposed to explain how small molecule drugs or their metabolites induce allergic drug hypersensitivity reactions. Meanwhile, direct activation of mast cells, provoking the complement system, stimulating or inhibiting inflammatory reaction-related enzymes, accumulating bradykinin, and/or triggering vascular hyperpermeability are considered as the main factors causing non-allergic drug hypersensitivity reactions. To date, many investigations have been performed to explore the underlying mechanisms involved in drug hypersensitivity reactions and to search for predictive and preventive methods in both clinical and non-clinical trials. However, validated methods for predicting and diagnosing hypersensitivity reactions to small molecule drugs and deeper insight into the relevant underlying mechanisms are still limited.

Anaphylaxis: Definition, Epidemiology, Diagnostic Challenges, Grading System

There are many definitions of anaphylaxis in the medical literature. The authors propose a modified definition of anaphylaxis to be used for clinical decision making that promotes the early utilization of intramuscular epinephrine. Anaphylaxis can be a result of an allergic or nonallergic mechanism. In general, allergic reactions are more severe; however, any type of anaphylaxis can result in death and improve with IM epinephrine. The World Allergy Organization's Grading Criteria for allergic systemic reactions are adapted as a guide to identify manifestations that may progress to anaphylaxis. The intent is to promote and encourage the use of IM epinephrine in the health care setting before the progression of manifestations and the onset of life-threatening respiratory or cardiovascular dysfunction generally recognized as meeting the definition of anaphylaxis.

Therapeutic Potential of MRGPRX2 Inhibitors on Mast Cells

Mast cells (MCs) act as primary effectors in inflammatory and allergic reactions by releasing intracellularly-stored inflammatory mediators in diseases. The two major pathways for MC activation are known to be immunoglobulin E (IgE)-dependent and -independent. Although IgE-dependent signaling is the main pathway to MC activation, IgE-independent pathways have also been found to serve pivotal roles in the pathophysiology of various inflammatory conditions. Recent studies have shown that human and mouse MCs express several regulatory receptors such as toll-like receptors (TLRs), CD48, C300a, and GPCRs, including mas-related GPCR-X2 (MRGPRX2). MRGPRX2 has been reported as a novel GPCR that is expressed in MCs activated by basic secretagogues, neurokinin peptides, host defense antimicrobial peptides, and small molecule compounds (e.g., neuromuscular blocking agents) and leads to MC degranulation and eicosanoids release under in vitro experimental condition. Functional analyses of MRGPRX2 and Mrgprb2 (mouse ortholog) indicate that MRGPRX2 is involved in MC hypersensitivity reactions causing neuroinflammation such as postoperative pain, type 2 inflammation, non-histaminergic itch, and drug-induced anaphylactic-like reactions. In this review, we discuss the roles in innate immunity through functional studies on MRGPRX2-mediated IgE-independent MC activation and also the therapeutic potential of MRGPRX2 inhibitors on allergic and inflammatory diseases.

Preparation and Evaluation of Lipid Emulsion Containing 13 Vitamins for Injection Without Anaphylactoid Reactions

Objective

Multivitamins containing Tween 80 can cause anaphylactoid reactions. The objective of this study was to develop a new lipid emulsion containing 13 fat- and water-soluble vitamins for injection (13V-LE) that were simultaneously dissolved in one bottle and to evaluate the stability of and anaphylactoid reactions to 13V-LE.

Methods

Particle size, ζ-potential, and polydispersity of 13V-LE were assayed with a Zetasizer Nano ZS. Entrapment efficiency of 13V-LE was determined with HPLC. Behavior, histamine, and blood pressure of beagle dogs were investigated by observation, fluorospectrophotometry, and sphygmomanometry.

Results

The 13V-LE with the smallest particles and highest entrapment efficiency with stable ζ-potential was composed of soybean oil, glycerin (2.25%, w:v), egg lecithin (1.2%, w:v), and purified water. There was no obvious change in characteristics of the 13V-LE samples in terms of appearance, size distribution, ζ-potential, pH value, or concentration over 6 months. In anaphylactoid reactions tests, when being administered with the multivitamin Infuvite Adult containing Tween 80, six beagles showed grade IV symptoms (P<0.01 vs control), low blood pressure, and high plasma-histamine concentrations (P<0.05 or P<0.01). However, there were no significant differences in behavior, blood pressure, or histamine concentration in the dogs before and after administration in the 13V-LE group.

Conclusion

The 13V-LE formulation is a suitable intravenous lipid emulsion without anaphylactoid reactions.

Non-IgE-mediated anaphylaxis

Anaphylaxis is a rapidly evolving, acute, life-threatening reaction that occurs rapidly on contact with a trigger. Anaphylaxis is classically defined as an allergen-driven process that induces specific IgE and the activation of mast cells and basophils through the cross-linking of IgE receptors. However, it is clear that non-IgE-mediated pathways can induce symptoms indistinguishable from those of classic anaphylaxis, and their activation could explain the severity of IgE-mediated anaphylaxis. Indeed, mast cells and basophils can be activated by antibodies against IgE or their receptors, by molecules such as anaphylatoxins, or through G-coupled receptors. Some other allergens can induce antibodies of class IgG that can activate neutrophils to produce a molecule similar to histamine to induce anaphylaxis. Finally, some inflammatory mediators such as bradykinin or prostaglandin can also modulate mast cell and basophil activation as well as directly cause vasodilation and bronchoconstriction, resulting in anaphylaxis-like reactions.

Safety of the Xuesaitong injection in China: results from a large-scale multicentre post-marketing surveillance study in a real-world setting

OBJECTIVE

The safety profile of traditional Chinese medicine injections has emerged as the greatest challenge to their clinical application. The authors aimed to perform a post-marketing surveillance study in a real-world setting to evaluate the safety of the Xuesaitong (XST) injection in China.

METHODS

This multi-centre, post-marketing, observational study enrolled patients who received XST injections in 42 centres in China between March 2015 and November 2017. Adverse drug reactions (ADRs) and adverse drug events (ADEs) were collected and evaluated in a post-marketing database. Logistic regression analysis was performed to analyse the risk factors for ADRs.

RESULTS

A total of 30,008 consecutive patients with a mean age of 62.29 ± 14.58 years were included in this post-marketing study. The incidences of ADEs and ADRs were 0.5% and 0.33%, respectively. The most common clinical manifestations were damage to skin and appendages (47.66%). There were four new kinds of ADEs found in the present monitoring study. The majority of ADRs were type B (62.62%) and occurred within 24 h after XST injection treatment. No severe ADRs were reported in this analysis. Multivariate logistic regression analysis showed that the hospital level (OR = 0.607; 95% CI = 0.407-0.906; p = .0144), hypertension (OR = 1.979; 95% CI, 1.323-2.959; p = .0009) and solvent type (OR = 2.951; 95% CI, 1.608-5.417; p = .0005) were risk factors for ADR occurrence.

CONCLUSION

XST injection is well tolerated and has a favourable safety profile for patients in a real-world setting. This post-marketing study provided further evidence of the safety of XST injections for clinical applications.

5-HMF induces anaphylactoid reactions in vivo and in vitro

AIM

Excessive exposure to 5-hydroxymethylfurfural (5-HMF), which is a common impurity in various sugar-containing products, induces serious side effects. Our previous study revealed that 5-HMF exerted immune sensitizing potential when injected into rodents. In this study, we explored 5-HMF mediated anaphylactoid reactions and its underlying molecular mechanisms.

METHODS

We investigated anaphylactoid reactions in Brown Norway (BN) rats and Institute of Cancer Research (ICR) mice to identify 5-HMF mediated in vivo anaphylactoid reactions. RBL-2H3 and P815 cell degranulation models were also established, and degranulation, enzyme-linked immunosorbent, filamentous actin (F-actin) microfilament staining, and western blot assays were performed in these cells.

RESULTS

We showed that 5-HMF induced anaphylactoid reactions by increasing blood vessel permeability in mice, and significantly elevating histamine (His) and glutathione peroxidase-1 (Gpx-1) levels in rat serum. Moreover, after incubation with 5-HMF, β-hexosaminidase (β-Hex), His, IL-4 and IL-6 levels were all significantly increased, thereby inducing cellular degranulation in RBL-2H3 and P815 cells. Finally, 5-HMF also upregulated Lyn, Syk, p38 and JNK protein phosphorylation levels.

CONCLUSIONS

Our findings suggest that 5-HMF induces anaphylactoid reactions both in vivo and in vitro, therefore 5-HMF limits in sugar-containing products should receive more regulatory attention.

Adverse cutaneous reactions to chemotherapeutic drugs

Drug reactions resulting from chemotherapy agents are common and frequently affect the skin. Although often benign, a select few of these cutaneous reactions may necessitate immediate changes to the antineoplastic regimens. Given the diversity of chemotherapeutic skin reactions and their complex implications on patient management, an organized conceptual schema is imperative for proper patient care. We evaluate a number of commonly seen chemotherapy-induced skin toxicities organized by pathogenic mechanism and drug class, providing a framework for the identification and categorization of adverse events to prevent unrecognition. Groupings of these reactions include direct cytotoxicity and/or drug accumulation, immunologic hypersensitivity, and aberrant molecular signaling.

Hypersensitivity reaction of the gingiva to chlorhexidine: case report and literature review

OBJECTIVE

The aim of this case report was to document a case of delayed-type hypersensitivity reaction of the gingiva to chlorhexidine and review the literature on oral mucosal hypersensitivity reactions associated to chlorhexidine-containing oral hygiene products.

STUDY DESIGN

A 58-year-old man presented with a well-demarcated erythematous area on the right upper anterior gingiva. Incisional biopsy was performed. Postoperatively, chlorhexidine digluconate gel was prescribed twice a day, but the patient did not use it because he experienced intense burning immediately after the first application. The microscopic diagnosis was nonspecific mucositis. Hypersensitivity reaction was suspected. The patient reported use of 0.004% chlorhexidine digluconate-based toothpaste twice a day in the past few years. A delayed-type hypersensitivity reaction to the toothpaste was hypothesized, and its use was discontinued. Chlorhexidine, the common ingredient of both the toothpaste and the gel, was considered the allergen. The literature was reviewed on chlorhexidine-induced oral hypersensitivity reactions.

RESULTS

Two weeks after cessation of toothpaste use, complete remission of the lesion was observed without additional intervention. Four years later, no recurrence has been reported. The literature review yielded 7 studies reporting 20 patients with intraoral manifestations of hypersensitivity reactions associated with chlorhexidine-containing oral hygiene products.

CONCLUSIONS

Clinicians should be aware that oral hygiene products containing even low concentrations of chlorhexidine might induce hypersensitivity reactions.

The diagnosis of hypersensitivity to antibiotics is rarely confirmed by allergy work-up in cystic fibrosis patients

Cystic fibrosis (CF) patients receive many antibiotic treatments for recurrent respiratory infections and frequently report antibiotic hypersensitivity reactions (HSRs). In this retrospective study, medical records of CF patients were reviewed to clarify the clinical features, the culprit antibiotics, and the prevalence of antibiotic HSRs in the CF population. From 601 CF patients, 95 suspected antibiotic HSRs occurred in 60 patients (prevalence of 10.0%). β-Lactams were the most common inducers, but cotrimoxazole was also frequently involved. Seventy-six of 95 suspected HSRs were assessed by allergy workup including skin tests (43/76 reactions) and/or drug reintroduction as a full course of the culprit antibiotic (73 of 76 reactions). From the 43 suspected HSRs that were skin-tested, only three had positive skin tests and were not subjected to drug readministration. All the other 73 suspected HSRs received a full course of the culprit antibiotic: HSR symptoms recurred in 10 of 73 cases and therefore were considered as confirmed antibiotic HSRs; for the remaining 63 suspected HSRs that did not relapse after drug readministration, the diagnosis of antibiotic HSRs was excluded. In summary, 13 of 76 suspected HSRs were confirmed as antibiotic HSRs. The prevalence of suspected and confirmed antibiotic HSRs in CF patients appears similar to that reported in the general population. Of note, most of the antibiotic suspected HSRs are not confirmed after allergology workup. A complete allergy workup appears therefore crucial to make a correct diagnosis and to avoid unnecessary contraindication of major antibiotics.

Eremomycin pyrrolidide: a novel semisynthetic glycopeptide with improved chemotherapeutic properties

PURPOSE

Development of new semisynthetic glycopeptides with improved antibacterial efficacy and reduced pseudoallergic reactions.

METHODS

Semisynthetic glycopeptides 3-6 were synthesized from vancomycin (1) or eremomycin (2) by the condensation with pyrrolidine or piperidine. The minimum inhibitory concentration (MIC) for the new derivatives was measured by the broth micro-dilution method on a panel of clinical isolates of Staphylococcus and Enterococcus. Acute toxicity (50% lethal dose, maximum tolerated doses), antibacterial efficacy on model of systemic bacterial infection with S. aureus and pseudoallergic inflammatory reaction (on concanavalin A) of eremomycin pyrrolidide (5) were evaluated in mice according to standard procedures.

RESULTS

The eremomycin pyrrolidide (5) was the most active compound and showed a high activity against Gram-positive bacteria: vancomycin-susceptible staphylococci and enterococci (minimum inhibitory concentrations [MICs] 0.13-0.25 mg/L), as well as vancomycin-intermediate resistant Staphylococcus aureus (MICs 1 mg/L). Antimicrobial susceptibility tested on a panel of 676 isolates showed that 5 had similar activity for the genera Staphylococcus and Enterococcus with MIC90=0.5 mg/L, while vancomycin had MIC90=1-2 mg/L. The number of resistant strains of Enterococcus faecium (vancomycin-resistant enterococci) (MIC =64 mg/L) with this value was 7 (8%) for vancomycin (1) and 0 for the compound 5. In vivo comparative studies in a mouse model of systemic bacterial infection with S. aureus demonstrated that the efficacy of 5 was notably higher than that of the original antibiotics 1 and 2. In contrast to 1, compound 5 did not induce pseudoallergic inflammatory reaction (on concanavalin A).

CONCLUSION

The new semisynthetic derivative eremomycin pyrrolidide (5) has high activity against staphylococci and enterococci including vancomycin-resistant strains. Compound 5 has a higher efficacy in a model of staphylococcal sepsis than vancomycin (1) or eremomycin (2). In striking contrast to natural antibiotics, the novel derivative 5 does not induce a pseudoallergic inflammatory reaction to concanavalin A and therefore has no histamine release activity. These results indicate the advantages of a new semisynthetic glycopeptide antibiotic eremomycin pyrrolidide (5) which may be a prospective antimicrobial agent for further pre-clinical and clinical evaluations.

Cisatracurium induces mast cell activation and pseudo-allergic reactions via MRGPRX2

BACKGROUND

Pseudo-allergic reactions occur when patients receive muscle relaxants during perioperative anesthesia. These reactions may result in a serious threat to the patient's life, particularly to a child's life. Cisatracurium, a relatively new NMBA, has resulted in bronchospasms and cardiovascular collapse. However, the mechanisms underlying the anaphylactoid reactions caused by cisatracurium have not been fully elucidated.

METHODS

In the present study, the MRGPRX2-related pseudo-allergic reactions induced by cisatracurium were investigated using hindpaw swelling and extravasation assays in vivo and mast cell degranulation assays.

RESULTS

Cisatracurium caused anaphylactoid reactions in wild-type mice. However, cisatracurium did not induce a similar phenomenon in KitW-sh/W-sh mice. Furthermore, mast cell-related G protein-coupled receptor B2-knockout mice did not display an inflammatory response upon treatment with cisatracurium. Cisatracurium induced LAD2 cell degranulation, leading to the dose-dependent release of β-hexosaminidase, histamine and TNF-α. However, cisatracurium only induced the release of low levels of these mediator LAD2 cells transfected with MRGPRX2 siRNA. Cisatracurium also stimulated intracellular Ca²⁺ influx in MRGPRX2-HEK293 cells compared with that in NC-HKE293 cells. Interestingly, cytokine release was not observed in LAD2 cells even with high dose of cisatracurium.

CONCLUSIONS

Cisatracurium activated MRGPRX2 and triggered mast cell degranulation, leading to anaphylactoid reactions. Therefore, strategies targeting MRGPRX2 might potentially block cisatracurium-induced pseudo-allergic reactions.

Importance of hypersensitivity in adverse reactions to drugs in the elderly

Background

The use of drugs in the elderly is very extensive because of the frequent occurrence of chronic diseases. Adverse drug reactions (ADRs) commonly occur in geriatric patients receiving multiple therapeutic regimens. In the literature, little attention has been given to ADRs in the elderly, and particularly to allergic reactions.

Objective

The aim of the present study is to provide data on possible inappropriate prescriptions in the elderly in relation to allergic reactions and to identify a list of drugs which are likely inducers of allergic reactions.

Methods

We retrospectively evaluated ADRs in patients referring to Immunoallergy Unit of Hospital Policlinico in Bari on the basis of Beers criteria. Among adverse reactions, hypersensitivity reactions were extracted and a comparison between different age groups was assessed.

Results

Out of 823 patients with ADRs, in 30.6% hypersensitivity drug reactions (HDR) were diagnosed. Data about drug intake, comorbidities and clinical presentation were collected, aiming to identify possible risk factors. An evaluation of drugs most commonly involved was assessed.

Conclusions

HDR are reported to represent 5-10% of all ADRs, while in our study population the prevalence was about 30%. This suggests the need to develop strategies to minimize the incidence of drug allergy in the elderly, as well to reduce the phenomenon of inappropriate prescriptions.

An Updated Review of the Molecular Mechanisms in Drug Hypersensitivity

Drug hypersensitivity may manifest ranging from milder skin reactions (e.g., maculopapular exanthema and urticaria) to severe systemic reactions, such as anaphylaxis, drug reactions with eosinophilia and systemic symptoms (DRESS)/drug-induced hypersensitivity syndrome (DIHS), or Stevens–Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN). Current pharmacogenomic studies have made important strides in the prevention of some drug hypersensitivity through the identification of relevant genetic variants, particularly for genes encoding drug-metabolizing enzymes and human leukocyte antigens (HLAs). The associations identified by these studies are usually drug, phenotype, and ethnic specific. The drug presentation models that explain how small drug antigens might interact with HLA and T cell receptor (TCR) molecules in drug hypersensitivity include the hapten theory, the p-i concept, the altered peptide repertoire model, and the altered TCR repertoire model. The broad spectrum of clinical manifestations of drug hypersensitivity involving different drugs, as well as the various pathomechanisms involved, makes the diagnosis and management of it more challenging. This review highlights recent advances in our understanding of the predisposing factors, immune mechanisms, pathogenesis, diagnostic tools, and therapeutic approaches for drug hypersensitivity.

RhoA/ROCK Signaling Pathway Mediates Shuanghuanglian Injection-Induced Pseudo-allergic Reactions

Background: Shuanghuanglian injection (SHLI) is a famous Chinese medicine used as an intravenous preparation for the treatment of acute respiratory tract infections. In the recent years, the immediate hypersensitivity reactions induced by SHLI have attracted broad attention. However, the mechanism involved in these reactions has not yet been elucidated. The present study aims to explore the characteristics of the immediate hypersensitivity reactions induced by SHLI and deciphers the role of the RhoA/ROCK signaling pathway in these reactions.

Methods: SHLI-immunized mice or naive mice were intravenously injected (i.v.) with SHLI (600 mg/kg) once, and vascular leakage in the ears was evaluated. Passive cutaneous anaphylaxis test was conducted using sera collected from SHLI-immunized mice. Naive mice were administered (i.v.) with a single dose of 150, 300, or 600 mg/kg of SHLI, and vascular leakage, histamine release, and histopathological alterations in the ears, lungs, and intestines were tested. In vitro, human umbilical vein endothelial cell (HUVEC) monolayer was incubated with SHLI (0.05, 0.1, or 0.15 mg/mL), and the changes in endothelial permeability and cytoskeleton were observed. Western blot analysis was performed and ROCK inhibitor was employed to investigate the contribution of the RhoA/ROCK signaling pathway in SHLI-induced hypersensitivity reactions, both in HUVECs and in mice.

Results: Our results indicate that SHLI was able to cause immediate dose-dependent vascular leakage, edema, and exudates in the ears, lungs, and intestines, and histamine release in mice. These were pseudo-allergic reactions, as SHLI-specific IgE was not elicited during sensitization. In addition, SHLI induced reorganization of actin cytoskeleton and disrupted the endothelial barrier. The administration of SHLI directly activated the RhoA/ROCK signaling pathway both in HUVECs and in the ears, lungs, and intestines of mice. Fasudil hydrochloride, a ROCK inhibitor, ameliorated the SHLI-induced hypersensitivity reactions in both endothelial cells and mice indicating its protective effect. SHLI-induced pseudo-allergic reactions were mediated by the activation of the RhoA/ROCK signaling pathway.

Conclusion: This study presents a novel mechanism of SHLI-induced immediate hypersensitivity reactions and suggests a potential therapeutic strategy to prevent the associated adverse reactions.

Drug desensitization in 17-year-old male with Mast Cell Activation Syndrome, pneumonia, and antibiotic hypersensitivities

Rapid desensitization (RD) is utilized in order to provide necessary medications to patients with drug hypersensitivity. RD is performed in a closely monitored setting to protect patients from severe anaphylactic or anaphylactoid reactions. A recently classified syndrome, mast cell activation syndrome (MCAS), has been defined by episodic symptoms caused by mast cell mediators and is associated with specific laboratory markers. Patient with MCAS and history of systemic reactions to ceftriaxone and azithromycin presented with pneumonia requiring treatment with ceftriaxone and azithromycin, both provided via desensitization protocols. Desensitization for drug hypersensitivities in the setting of MCAS presents several controversial issues as mechanism of hypersensitivity may not be related to IgE-mediated but rather non-specific mast-cell degranulation. The controversies of diagnosis and management of antibiotic hypersensitivity in patients with MCAS discussed. Our case demonstrates that desensitization protocols can be used in MCAS patients with noted hypersensitivities. The intricacies of desensitization in the setting of MCAS are not fully understood and will require further research and characterization.

Typical antimicrobials induce mast cell degranulation and anaphylactoid reactions via MRGPRX2 and its murine homologue MRGPRB2

Mast cells are unique immune cells that function as sentinels in host defence reactions, including immediate hypersensitivity responses and allergic responses. The mast cell-specific receptor named MAS-related G protein-coupled receptor X2 (MRGPRX2) triggers mast-cell degranulation, a key process in anaphylactoid reactions. It is widely observed that antimicrobials can induce pseudo-allergic reactions (i.e. IgE-independent mechanism) with symptoms ranging from skin inflammation to life-threatening systemic anaphylaxis. However, their direct involvement and the mechanisms underlying anaphylactoid reactions caused by antimicrobials have not been demonstrated. Structurally different antimicrobials were screened by Ca²⁺ imaging using MRGPRX2 overexpressing HEK293 cells. MRGPRX2 related anaphylactoid reactions induced by these components were investigated by body temperature drop and mast cell degranulation assays. We showed that MRGPRX2 is involved in allergic-like reactions to three types of antimicrobials in a dose-dependent manner. However, mast cells lacking the receptor show reduced degranulation. Furthermore, mice without MAS-related G protein-coupled receptor B2 (the orthologous gene of MRGPRX2) exhibited reduced substance-induced inflammation. Interestingly, β-lactam and antiviral nucleoside analogues did not induce anaphylactic reactions, which were also observed in vitro. These results should alarm many clinicians that such drugs might induce anaphylactoid reactions and provide guidance on safe dosage of these drugs.

Ginsenoside F2 induces the release of mediators associated with Anaphylactoid reactions

Recently, the allergenicity of ginsenosides, as main active components in ginseng, has attracted much attention. Ginsenoside Rb1 and Rd. have been reported to induce anaphylactoid reaction. In this study, the allergenicity of a series of 20(S)-protopanaxadiol (PPD) type ginsenosides, including Rb1, Rd., F2, Compound K and 20(S)-PPD, was evaluated in rat basophilic leukemia 2H3 (RBL2H3) cells. As a result, 20(S)-PPD had no effect on the mast cell degranulation, but other components showed anaphylactoid potential to different extent. The allergenicity was stronger and stronger according to the order "Rb1, Rd., F2, Compound K". Then, F2 was further verified in RBL-2H3 cells, mouse peritoneal mast cells (MPMCs), Laboratory of Allergic Disease 2 (LAD2) human mast cells in vitro and mice in vivo. Results showed that F2 could induce a significant increase of histamine release and translocation of phosphatidylserine in RBL-2H3 cells. F2 also increased β-hexosaminidase release and the intracellular Ca²⁺ concentration of MPMCs and LAD2 cells. In addition, histamine level in serum of mice was elevated dose-dependently. Our study revealed the potential structure-allergenicity relationship of 20(S)-PPD type ginsenosides and first verified the allergenicity of ginsenoside F2. This study could guide the establishment of quality standards for safe application of ginsenoside-containing preparations.

Reclassifying Anaphylaxis to Neuromuscular Blocking Agents Based on the Presumed Patho-Mechanism: IgE-Mediated, Pharmacological Adverse Reaction or "Innate Hypersensitivity"?

Approximately 60% of perioperative anaphylactic reactions are thought to be immunoglobulin IgE mediated, whereas 40% are thought to be non-IgE mediated hypersensitivity reactions (both considered non-dose-related type B adverse drug reactions). In both cases, symptoms are elicited by mast cell degranulation. Also, pharmacological reactions to drugs (type A, dose-related) may sometimes mimic symptoms triggered by mast cell degranulation. In case of hypotension, bronchospasm, or urticarial rash due to mast cell degranulation, identification of the responsible mechanism is complicated. However, determination of the type of the underlying adverse drug reaction is of paramount interest for the decision of whether the culprit drug may be re-administered. Neuromuscular blocking agents (NMBA) are among the most frequent cause of perioperative anaphylaxis. Recently, it has been shown that NMBA may activate mast cells independently from IgE antibodies via the human Mas-related G-protein-coupled receptor member X2 (MRGPRX2). In light of this new insight into the patho-mechanism of pseudo-allergic adverse drug reactions, in which as drug-receptor interaction results in anaphylaxis like symptoms, we critically reviewed the literature on NMBA-induced perioperative anaphylaxis. We challenge the dogma that NMBA mainly cause IgE-mediated anaphylaxis via an IgE-mediated mechanism, which is based on studies that consider positive skin test to be specific for IgE-mediated hypersensitivity. Finally, we discuss the question whether MRGPRX2 mediated pseudo-allergic reactions should be re-classified as type A adverse reactions.

Alternative Anaphylactic Routes: The Potential Role of Macrophages

Anaphylaxis is an acute, life-threatening, multisystem syndrome resulting from the sudden release of mediators from effector cells. There are two potential pathways for anaphylaxis. The first one, IgE-dependent anaphylaxis, is induced by antigen (Ag) cross-linking of Ag-specific IgE bound to the high-affinity IgE receptor (FcεRI) on mast cells and basophils. The second one, IgG-dependent anaphylaxis is induced by Ag cross-linking of Ag-specific IgG bound to IgG receptors (FcγRI, FcγRIIA, FcγRIIB, FcγRIIC, and FcγRIIIA) on macrophages, neutrophils, and basophils. Macrophages exhibit a huge functional plasticity and are capable of exerting their scavenging, bactericidal, and regulatory functions under a wide variety of tissue conditions. Herein, we will review their potential role in the triggering and development of anaphylaxis. Thereby, macrophages, among other immune cells, play a role in both anaphylactic pathways (1) by responding to anaphylactic mediators secreted by mast cells after specific IgE cross-linking or (2) by acting as effector cells in the anaphylactic response mediated by IgG. In this review, we will go over the cellular and molecular mechanisms that take place in the above-mentioned anaphylactic pathways and will discuss the clinical implications in human allergic reactions.

In Vivo Cysteinyl Leukotriene Release in Allergic and Nonallergic Immediate Hypersensitivity Reactions during Anesthesia

BACKGROUND

Immediate hypersensitivity reactions occurring during anesthesia are classified as allergic when skin tests and mast cell tryptase are positive and as nonallergic when negative results are obtained. Cysteinyl leukotrienes (cysLTs) are potent mediators synthesized by mast cell and eosinophil that induce bronchial constriction. They could play a role in hypersensitivity reactions.

METHODS

cysLT C4, D4, and E4 concentrations were measured by a competition immunoassay in serial plasma samples obtained prospectively from 21 anesthetized controls and retrospectively from 34 patients who reacted at induction of anesthesia (24 with allergic and 10 with nonallergic reactions).

RESULTS

In controls, the median (interquartile range) cysLT concentration was 0.83 (0.69 to 1.02) μg/l before anesthesia and was unchanged 30 min, 6 h, and 24 h afterward. In the patients with allergic reactions, the values were highly increased 30 to 60 min after the reaction (17.9 [7.8 to 36.0] μg/l), while the patients with nonallergic reactions had less increased values (7.3 [3.0 to 11.5] μg/l). The difference between the three groups was significant (P < 0.0001). Increased values persisted during the 24 h of observation. Concentrations were significantly higher in patients with bronchospasm (P = 0.016).

CONCLUSIONS

cysLTs appear to be an important mediator of allergic and nonallergic immediate hypersensitivity reactions. These findings might open a new field for management of patients with hypersensitivity reactions, especially nonallergic ones.

Pharmacogenomics of off-target adverse drug reactions

Off-target adverse drug reactions (ADRs) are associated with significant morbidity and costs to the healthcare system, and their occurrence is not predictable based on the known pharmacological action of the drug's therapeutic effect. Off-target ADRs may or may not be associated with immunological memory, although they can manifest with a variety of shared clinical features, including maculopapular exanthema, severe cutaneous adverse reactions (SCARs), angioedema, pruritus and bronchospasm. Discovery of specific genes associated with a particular ADR phenotype is a foundational component of clinical translation into screening programmes for their prevention. In this review, genetic associations of off-target drug-induced ADRs that have a clinical phenotype suggestive of an immunologically mediated process and their mechanisms are highlighted. A significant proportion of these reactions lack immunological memory and current data are informative for these ADRs with regard to disease pathophysiology, therapeutic targets and biomarkers which may identify patients at greatest risk. Although many serious delayed immune-mediated (IM)-ADRs show strong human leukocyte antigen associations, only a small subset have successfully been implemented in screening programmes. More recently, other factors, such as drug metabolism, have been shown to contribute to the risk of the IM-ADR. In the future, pharmacogenomic targets and an understanding of how they interact with drugs to cause ADRs will be applied to drug design and preclinical testing, and this will allow selection of optimal therapy to improve patient safety.

Adverse Medication Reactions

Cutaneous adverse drug reactions (ADRs) are among the most frequent adverse reactions in patients receiving drug therapy. They have a broad spectrum of clinical manifestations, are caused by various drugs, and result from different pathophysiological mechanisms. Hence, their diagnosis and management is challenging.

Severe cutaneous ADRs comprise a group of diseases with major morbidity and mortality, reaching 30 % mortality rate in cases of Toxic Epidermal Necrolysis.

This chapter covers the terminology, epidemiology, pathogenesis and classification of cutaneous ADR, describes the severe cutaneous ADRs and the clinical and laboratory approach to the patient with cutaneous ADR and presents the translation of laboratory-based discoveries on the genetic predisposition and pathogenesis of cutaneous ADRs to clinical management guidelines.

Involvement of Histamine and RhoA/ROCK in Penicillin Immediate Hypersensitivity Reactions

The mechanism of penicillin immediate hypersensitivity reactions has not been completely elucidated. These reactions are generally considered to be mediated by IgE, but penicillin-specific IgE could not be detected in most cases. This study demonstrated that penicillin was able to cause vascular hyperpermeability in a mouse model mimicking clinical symptoms of penicillin immediate hypersensitivity reactions. The first exposure to penicillin also induced immediate edema and exudative reactions in ears and lungs of mice in a dose-dependent manner. Vasodilation was noted in microvessels in ears. These reactions were unlikely to be immune-mediated reactions, because no penicillin-specific IgE was produced. Furthermore, penicillin treatment directly elicited rapid histamine release. Penicillin also led to F-actin reorganization in human umbilical vein endothelial cells and increased the permeability of the endothelial monolayer. Activation of the RhoA/ROCK signaling pathway was observed in ears and lungs of mice and in endothelial cells after treatment with penicillin. Both an anti-histamine agent and a ROCK inhibitor attenuated penicillin immediate hypersensitivity reactions in mice. This study presents a novel mechanism of penicillin immediate hypersensitivity reactions and suggests a potential preventive approach against these reactions.

A standard for terminology in chronic pelvic pain syndromes: A report from the chronic pelvic pain working group of the international continence society

AIMS

Terms used in the field of chronic pelvic pain (CPP) are poorly defined and often confusing. An International Continence Society (ICS) Standard for Terminology in chronic pelvic pain syndromes (CPPS) has been developed with the aim of improving diagnosis and treatment of patients affected by chronic pelvic pain syndromes. The standard aims to facilitate research, enhance therapy development and support healthcare delivery, for healthcare providers, and patients. This document looks at the whole person and all the domains (organ systems) in a systematic way.

METHODS

A dedicated working group (WG) was instituted by the ICS Standardisation Steering Committee according to published procedures. The WG extracted information from existing relevant guidelines, consensus documents, and scientific publications. Medline and other databases were searched in relation to each chronic pelvic pain domain from 1980 to 2014. Existing ICS Standards for terminology were utilized where appropriate to ensure transparency, accessibility, flexibility, and evolution. Consensus was based on majority agreement.

RESULTS

The multidisciplinary CPPS Standard reports updated consensus terminology in nine domains; lower urinary tract, female genital, male genital, gastrointestinal, musculoskeletal, neurological aspects, psychological aspects, sexual aspects, and comorbidities. Each is described in terms of symptoms, signs and further evaluation.

CONCLUSION

The document presents preferred terms and definitions for symptoms, signs, and evaluation (diagnostic work-up) of female and male patients with chronic pelvic pain syndromes, serving as a platform for ongoing development in this field. Neurourol. Urodynam. 36:984-1008, 2017. © 2016 Wiley Periodicals, Inc.

Human IgE-independent systemic anaphylaxis

Anaphylaxis is a rapidly developing, life-threatening, generalized or systemic allergic reaction that is classically elicited by antigen crosslinking of antigen-specific IgE bound to the high-affinity IgE receptor FcεRI on mast cells and basophils. This initiates signals that induce cellular degranulation with release and secretion of vasoactive mediators, enzymes, and cytokines. However, IgE-independent mechanisms of anaphylaxis have been clearly demonstrated in experimental animals. These include IgG-dependent anaphylaxis, which involves the triggering of mediator release by IgG/antigen complex crosslinking of FcγRs on macrophages, basophils, and neutrophils; anaphylaxis mediated by binding of the complement-derived peptides C3a and C5a to their receptors on mast cells, basophils, and other myeloid cells; and direct activation of mast cells by drugs that interact with receptors on these cells. Here we review the mechanisms involved in these IgE-independent forms of anaphylaxis and the clinical evidence for their human relevance. We conclude that this evidence supports the existence of all 3 IgE-independent mechanisms as important causes of human disease, although practical and ethical considerations preclude their demonstration to the degree of certainty possible with animal models. Furthermore, we cite evidence that different clinical situations can suggest different mechanisms as having a primal role in anaphylaxis and that IgE-dependent and distinct IgE-independent mechanisms can act together to increase anaphylaxis severity. As specific agents become available that can interfere with mechanisms involved in the different types of anaphylaxis, recognition of specific types of anaphylaxis is likely to become important for optimal prophylaxis and therapy.

LC-ESI-TOF-MS-based metabolomic analysis of ginsenoside Rd-induced anaphylactoid reaction in mice

A ginsenoside Rd-induced anaphylactoid reaction in mice was investigated by LC-ESI-TOF-MS-based metabolomic analysis as well as general toxicological assessments.

Nonclinical evaluation of the potential for mast cell activation by an erythropoietin analog

The erythropoietin analog peginesatide was withdrawn from marketing due to unexpected severe anaphylactic reactions associated with administration of the multi-use formulation. The adverse events occurred rapidly following the first ever administration of the drug with most affected patients becoming symptomatic in less than 30min. This is most consistent with an anaphylactoid reaction due to direct activation of mast cells. Laboratory evaluation was undertaken using rat peritoneal mast cells as the model system. Initial studies showed that high concentrations of the formulated drug as well as formulated vehicle alone could cause mast cell degranulation as measured by histamine release. The purified active drug was not able to cause histamine release whereas the vehicle filtrate and lab created drug vehicle were equally potent at causing histamine release. Individual formulations of vehicle leaving one component out showed that histamine release was due to phenol. Dose response studies with phenol showed a very sharp dose response curve that was similar in three buffer systems. Cellular analysis by flow cytometry showed that the histamine release was not due to cell death, and that changes in light scatter parameters consistent with degranulation were rapidly observed. Limited testing with primary human mast cells showed a similar dose response of histamine release with exposure to phenol. To provide in vivo confirmation, rats were injected with vehicle formulated with various concentrations of phenol via a jugular vein cannula. Significant release of histamine was detected in blood samples taken 2min after dosing at the highest concentrations tested.

Hypersensitivity from intravenous iron products

In the last several years, intravenous therapy with iron products has been more widely used. Although it has been a standard procedure in dialysis-associated anemia since the early 1990s, its use is expanding to a host of conditions associated with iron deficiency, especially young women with heavy uterine bleeding and pregnancy. Free iron is associated with unacceptable high toxicity inducing severe, hemodynamically significant symptoms. Subsequently, formulations that contain the iron as an iron carbohydrate nanoparticle have been designed. With newer formulations, including low-molecular-weight iron dextran, iron sucrose, ferric gluconate, ferumoxytol, iron isomaltoside, and ferric carboxymaltose, serious adverse events are rare.

Coexistence of angioedema alone with impaired glucose tolerance

BACKGROUND

Most patients with chronic spontaneous urticaria (CSU) exhibit recurrent angioedema. As of yet, the pathogenesis of angioedema in CSU is largely unclear, especially when angioedema occurs in patients who do not develop wheals. Over the past years, we and others have repeatedly observed that patients with recurrent angioedema alone exhibit impaired glucose tolerance.

AIM

To assess blood glucose levels and glucose tolerance in these patients and to compare the results to those of CSU patients who do not develop angioedema.

METHODS

A total of 29 patients with angioedema alone (15 women, mean age 43.2 ± 12.8 years) and 33 CSU patients (17 women, mean age 41.9 ± 17 years) were investigated and compared for clinical features and laboratory values, including fasting and random blood glucose levels, and glycated hemoglobin (HbA1c%). All patients were subjected to oral glucose tolerance testing (OGTT).

RESULTS

Fasting plasma glucose levels, random blood glucose levels and OGTT glucose levels were significantly higher in patients with angioedema alone as compared to CSU patients. Glucose tolerance was impaired in 17 of 29 patients with angioedema alone (58.6%) and only in 2 of 33 CSU patients (6.1%). Patients were found to have an increased risk of high glucose (OR 1.74) and HbA1c (OR 1.83) blood levels and of developing a high BMI (OR 1.97).

CONCLUSION

Recurrent angioedema in patients who do not develop wheals appears to be associated with impaired glucose tolerance and elevated blood glucose levels. We recommend blood glucose measurements in patients with recurrent angioedema alone.

Anaphylaxis and urticaria

Anaphylaxis and urticaria are common presenting allergic complaints. Affecting up to 2% of the population, anaphylaxis is a serious, life-threatening allergic reaction. Although not life-threatening, urticaria is a rash of transient, erythematous, pruritic wheals that can be bothersome and affects up to 25% of the population. All cases of anaphylaxis warrant thorough clinical evaluation by the allergist-immunologist, although most cases of urticaria are self-limited and do not require specialist referral. This article offers an overview of our current knowledge on the epidemiology, pathogenesis, triggers, diagnosis, and treatment of anaphylaxis and urticaria.

Diagnostic value of histamine and tryptase concentrations in severe anaphylaxis with shock or cardiac arrest during anesthesia

BACKGROUND

The diagnosis of acute life-threatening allergic reactions during anesthesia relies on clinical signs, histamine and/or tryptase measurements, and allergic testing. In patients who die after the reaction, skin tests cannot be performed, and the effect of resuscitation manoeuvres on mediator concentrations is unknown. The authors compared plasma histamine and tryptase concentrations in patients with severe allergic reactions during anesthesia with those measured in patients with shock due to other causes.

METHODS

Patients with life-threatening allergic reactions were retrieved from a previous database (Group ALLERGY). All had positive allergy tests to administered agents. Patients with severe septic/cardiogenic shock or cardiac arrest (Group CONTROL) had histamine and tryptase measurements during resuscitation manoeuvres. Receiver operating characteristics curves were built to calculate the optimal mediator thresholds differentiating allergic reactions from others.

RESULTS

One hundred patients were included, 75 in Group ALLERGY (cardiovascular collapse, 67; cardiac arrest, 8) and 25 in Group CONTROL (shock, 11; cardiac arrest, 14). Mean histamine and tryptase concentrations remained unchanged throughout resuscitation in Group CONTROL and were significantly higher in Group ALLERGY. The optimal thresholds indicating an allergic mechanism were determined as 6.35 nmol/l for histamine (sensitivity: 90.7% [95% CI, 81.7 to 96.1]; specificity: 91.7% [73.0 to 98.9]) and 7.35 μg/l for tryptase (sensitivity: 92% [83.4 to 97.0]; specificity: 92% [73.9 to 99.0]).

CONCLUSIONS

Resuscitation manoeuvres by themselves did not modify mediator concentrations. Virtually all life-threatening reactions during anesthesia associated with mediator concentrations exceeding the thresholds were allergic events. These findings have potential forensic interest when a patient dies during anesthesia.