Allergy to rocuronium: from clinical suspicion to correct diagnosis

Mast cell versus basophil activation test in allergy: Current status

In the past two decades, we witnessed the evolution of the basophil activation test (BAT) from mainly research applications to a potential complementary diagnostic tool to document IgE-dependent allergies. However, BAT presents some technical weaknesses. Around 10%-15% of tested patients are non-responders, BAT can be negative immediately post-reaction and the use of fresh basophils, ideally analysed within 4 h of collection, restricts the number of tests that can be performed per sample. The need for fresh basophils is especially limiting when conducting batch analyses and interlaboratory comparisons to harmonize BAT methodology. These limitations significantly hinder the wider application of BAT and urge the development of alternative testing, such as the mast cell activation test (MAT). The essential difference between BAT and MAT is the heterogeneity of the starting material used to perform the assays. Mast cells are tissue-resident, so cannot be easily accessed. Current alternative sources for functional studies are generating primary human mast cells, differentiated from donor progenitor cells, or using immortalized mast cell lines. Hence, the methodological approaches for MAT are not only vastly different from BAT, but also different among MAT protocols. This review summarizes the advantages and disadvantages of BAT and MAT assays, dedicating special attention to elucidating the key differences between the cellular sources used and provides an overview of studies hitherto performed comparing BAT and MAT in the diagnosis of IgE-mediated food and drug allergies.

Biomarkers of immediate drug hypersensitivity

Immediate drug hypersensitivity reactions (IDHRs) are a burden for patients and the health systems. This problem increases when taking into account that only a small proportion of patients initially labelled as allergic are finally confirmed after an allergological workup. The diverse nature of drugs involved will imply different interactions with the immunological system. Therefore, IDHRs can be produced by a wide array of mechanisms mediated by the drug interaction with specific antibodies or directly on effector target cells. These heterogeneous mechanisms imply an enhanced complexity for an accurate diagnosis and the identification of the phenotype and endotype at early stages of the reaction is of vital importance. Currently, several endophenotypic categories (type I IgE/non-IgE, cytokine release, Mast-related G-protein coupled receptor X2 (MRGPRX2) or Cyclooxygenase-1 (COX-1) inhibition and their associated biomarkers have been proposed. A precise knowledge of endotypes will permit to discriminate patients within the same phenotype, which is crucial in order to personalise diagnosis, future treatment and prevention to improve the patient's quality of life.

Flow-based basophil activation test in immediate drug hypersensitivity. An EAACI task force position paper

Diagnosing immediate drug hypersensitivity reactions (IDHRs) can pose a significant challenge and there is an urgent need for safe and reliable tests. Evidence has emerged that the basophil activation test (BAT), an in vitro assay that mirrors the in vivo response, can be a complementary test for many drugs. In this position paper, members of Task Force (TF) "Basophil activation test in the evaluation of Drug Hypersensitivity Reactions" from the European Academy of Allergy and Clinical Immunology (EAACI) present the data from a survey about the use and utility of BAT in IDHRs in Europe. The survey results indicate that there is a great interest for using BAT especially for diagnosing IDHRs. However, there are still main needs, mainly in the standardization of the protocols. Subsequently consensus-based recommendations were formulated for: (i) Technical aspects of BAT in IDHRs including type of sample, management of drugs, flow cytometry protocols, interpretation of the results; and (ii) Drug-specific aspects that should be taken into account when performing BAT in relation to betalactams, neuromuscular blocking agents, fluoroquinolones, chlorhexidine, opioids, radio contrast media, chemotherapeutics, biological agents, nonsteroidal anti-inflammatory drugs, COVID vaccine, and excipients. Moreover, aspects in the evaluation of pediatric population have also been considered. All this indicates that BAT offers the clinician and laboratory a complementary tool for a safe diagnostic for IDHRs, although its place in the diagnostic algorithm depends on the drug class and patient population (phenotype, geography, and age). The standardization of BAT is important for generalizing this method beyond the individual laboratory.

Comparison of the passive mast cell activation test with the basophil activation test for diagnosis of perioperative rocuronium hypersensitivity

BACKGROUND

Rocuronium is a major cause of perioperative hypersensitivity (POH). Skin tests (STs) and quantification of specific immunoglobulin E antibodies (sIgEs) can yield incongruent results. In such difficult cases, the basophil activation test (BAT) can be helpful. Here, we evaluated the passive mast cell activation test (pMAT) as a substitute of BAT as part of the diagnostic tests for rocuronium allergy.

METHODS

Sera from patients with a suspected POH reaction potentially related to rocuronium were included. All patients had a complete diagnostic investigation, including STs, quantification of sIgEs to morphine and rocuronium, and BAT. For execution of pMAT, human mast cells were generated from healthy donor peripheral blood CD34+ progenitor cells and sensitised overnight with patient sera.

RESULTS

In total, 90 sera were studied: 41 from ST+sIgE+ patients, 13 from ST-sIgE- patients, 20 from ST+sIgE- patients, and 16 from ST-sIgE+ patients. According to BAT results, patients were further allocated into subgroups. Of the 38 BAT+ patients, 25 (66%) showed a positive pMAT as well. Of the 44 BAT- patients, 43 (98%) also showed a negative pMAT. Mast cells that were not passively sensitised did not respond to rocuronium.

CONCLUSIONS

We show that the pMAT, in many cases, can substitute for BAT in the diagnosis of rocuronium hypersensitivity and advance diagnosis in difficult cases with uncertain ST or sIgE results when BAT is not locally available.

Suspected perioperative anaphylaxis: are we making the correct diagnosis?

We provide a commentary on aspects of a prospective study of the epidemiology of perioperative anaphylaxis in Japan (Japanese Epidemiologic Study for Perioperative Anaphylaxis [JESPA]). Accurate diagnosis of perioperative anaphylaxis is important for research but essential for clinical safety. We evaluate the diagnostic approach used in the JESPA study and caution against over-reliance on diagnostic tests that lack sensitivity and specificity when clinical data suggest an immediate perioperative hypersensitivity reaction is likely.

A quarter of a century fundamental and translational research in perioperative hypersensitivity and anaphylaxis at the Antwerp university hospital, a Belgian Centre of Excellence of the World Allergy Organization

Perioperative hypersensitivity constitutes an important health issue, with potential dramatic consequences of diagnostic mistakes. However, safe and correct diagnosis is not always straightforward, mainly because of the application of incorrect nomenclature, absence of easy accessible in-vitro/ex-vivo tests and uncertainties associated with the non-irritating skin test concentrations. In this editorial we summarize the time line, seminal findings, and major realizations of 25 years of research on the mechanisms, diagnosis, and management of perioperative hypersensitivity.

Neuromuscular blocking agent induced hypersensitivity reaction exploration: an update

Acute hypersensitivity reactions (AHRs) occurring in present-day anaesthesia can have severe, sometimes fatal, consequences and their incidence is increasing. The most frequent allergens responsible for AHR during anaesthesia are neuromuscular blocking agents (NMBAs) (70% of the cases) followed by antibiotics (18%), patent blue dye and methylene blue dye (5%), and latex (5%). Following an AHR, strategies for subsequent anaesthetic procedures (especially the choice of an NMBA) may be difficult to formulate due to inconclusive diagnostic analysis in up to 30% of AHRs. Current diagnosis of AHR relies on the detection of mast cell degranulation products and drug-specific type E immunoglobulins (IgE) in order to document an IgE-mediated anaphylaxis (IgE endotype). Nonetheless, other IgE-independent pathways can be involved in AHR, but their detection is not currently available in standard situations. The different mechanisms (endotypes) involved in peri-operative AHR may contribute to the inconclusive diagnostic work-up and this generates uncertainty concerning the culpable drug and strategy for subsequent anaesthetic procedures. This review provides details on the IgE endotype; an update on non-IgE related endotypes and the novel diagnostic tools that could characterise them. This detailed update is intended to provide explicit clinical reasoning tools to the anaesthesiologist faced with an incomplete AHR diagnostic work-up and to facilitate the decision-making process regarding anaesthetic procedures following an AHR to NMBAs.

Clinical reasoning in anaphylactic shock: addressing the challenges faced by anaesthesiologists in real time: A clinical review and management algorithms

Acute hypersensitivity reactions to drugs occur infrequently during anaesthesia and the peri-operative period. When clinical presentation includes the classical triad, erythema, cardiovascular abnormalities and increased airway pressure, the diagnosis is evident and the challenge is to prescribe a therapeutic regimen according to guidelines and to manage refractory signs in a timely manner. In many situations, however, the initial clinical signs are isolated, such as increased airway pressure or arterial hypotension. Rendering a differential diagnosis with causes and mechanisms other than acute hypersensitivity reactions (AHRs) is difficult, delaying treatment with possible worsening of the clinical signs, and even death, in previously healthy individuals. In these difficult diagnostic situations, clinical reasoning is mandatory, and guidelines do not explicitly explain the elements on which clinical reasoning can be built. In this article, based on clinical evidence whenever available, experimental data and pathophysiology, we propose algorithms that have been evaluated by experts. The goal of these algorithms is to provide explicit elements on which the differential diagnosis of AHRs can be made, accelerating the implementation of adequate therapy.

Practical guidelines for the response to perioperative anaphylaxis

Perioperative anaphylaxis is a severe adverse event during anesthesia that requires prompt diagnosis and treatment by physicians, including anesthesiologists. Muscle relaxants and antibiotics are the most common drugs that cause perioperative anaphylaxis in Japan, as in many countries. In addition, sugammadex appears to be a primary causative agent. Obtaining previous anesthesia records is necessary in a patient with a history of allergic reactions during anesthesia, whenever possible, to avoid recurrence of anaphylaxis. Although medical staff are likely to notice abnormal vital signs because of complete monitoring during anesthesia, surgical drapes make it difficult to notice the appearance of skin symptoms. Even if there are no skin symptoms, anaphylaxis should be suspected, especially when hypotension resistant to inotropes and vasopressors persists. For improving the diagnostic accuracy of anaphylaxis, it is helpful to collect blood samples to measure histamine/tryptase concentrations immediately after the events and at baseline. The first-line treatment for anaphylaxis is adrenaline. In the perioperative setting, adrenaline should be administered through the intravenous route, which has a faster effect onset and is secured in most cases. Adrenaline can cause serious complications including severe arrhythmias if the appropriate dose is not selected according to the severity of symptoms. The anesthesiologist should identify the causative agent after adverse events. The gold standard for identifying the causative agent is the skin test, but in vitro tests including specific IgE antibody measurements and basophil activation tests are also beneficial. The Working Group of the Japanese Society of Anesthesiologists has developed this practical guide to help appropriate prevention, early diagnosis and treatment, and postoperative diagnosis of anaphylaxis during anesthesia.Grade of recommendations and levels of evidence Anaphylaxis is a relatively rare condition with few controlled trials, and thus a so-called evidence-based scrutiny is difficult. Therefore, rather than showing evidence levels and indicating the level of recommendation, this practical guideline only describes the results of research available to date. The JSA will continue to investigate anaphylaxis during anesthesia, and the results may lead to an amendment of this practical guideline.

Novel Insights on MRGPRX2-Mediated Hypersensitivity to Neuromuscular Blocking Agents And Fluoroquinolones

Neuromuscular blocking agents (NMBAs) like atracurium and rocuronium as well as fluoroquinolones (FQs) cause mast cell-mediated anaphylaxis by activating Mas-related G protein-coupled receptor X2 (MRGPRX2), but many questions remain unanswered. Here, we address three of them, namely whether primary human mast cells show similar activation by these drugs as murine mast cells and mast cell lines, how sugammadex protects from atracurium-induced MRGPRX2-mediated mast cell activation, and why some but not all patients treated with rocuronium develop anaphylaxis. We used peripheral blood-derived cultured mast cells from healthy donors and patients, assessed mast cell activation and degranulation by quantifying intracellular calcium and CD63 expression, respectively, and made use of MRGPRX2-silencing, via electroporation with Dicer-substrate small interfering RNAs, and single cell flow cytometric analyses. Atracurium, ciprofloxacin, and levofloxacin activated and degranulated primary human mast cells, but only MRGPRX2-positive and not MRGPRX2-negative or -silenced mast cells. Sugammadex attenuated the atracurium-induced and MRGPRX2-mediated activation and degranulation of human mast cells by reducing free atracurium levels. The mast cells of patients with IgE-independent anaphylaxis to rocuronium were similar, in their MRGPRX2 expression and function, to those of patients with IgE-mediated anaphylaxis. These findings further improve our understanding of the role and relevance of MRGPRX2-driven mast cell activation in anaphylactic reactions to NMBAs and FQs and may help to improve their prediction, prevention, and treatment.

Detection of drug-specific immunoglobulin E (IgE) and acute mediator release for the diagnosis of immediate drug hypersensitivity reactions

The diagnosis of a drug hypersensitivity reaction (DHR) is complex. The first step after taking the clinical history is to look for a sensitization to confirm or exclude the diagnosis and to identify the culprit drug. Skin tests are the primary means of detecting sensitization in DHR, but are associated with a risk for a severe reaction and may be contraindicated. In vitro tests offer the potential to support or confirm a diagnosis of DHR and influence medical decision making. For immediate-type DHR, a few validated assays for measurement of specific IgE (sIgE) are commercially available to a limited number of drugs. In addition, several home-made sIgE radioimmunoassays have been used in other studies. The sensitivity of the sIgE assay is drug-dependant and generally low (0-85%) for betalactams and reported heterogeneous for other drugs ranging from 26% for chlorhexidine and 44% for suxamethonium to 92% for chlorhexidine. However, as all these studies included patients, in whom DHR was confirmed only by skin tests and not by provocation, the results have to be interpreted carefully and may be unreliable. Determination of mediators during an acute phase of a reaction may indirectly support the diagnosis of a DHR by demonstrating mast cell and basophil mediator release. Negative in vitro tests do not exclude a DHR or imputability of a drug, but a positive result may support causality and eliminate the necessity for a drug provocation test. Unfortunately, evidence is limited with a lack of well-controlled studies in larger numbers of well-phenotyped patients, which results in susceptibility for bias and a need for future multicenter studies.

Triggers of Exacerbation in Chronic Urticaria and Recurrent Angioedema-Prevalence and Relevance

Patients with urticaria and angioedema often have triggers that cause an outbreak or a swelling episode or worsen their chronic condition. Exploring these factors with each patient may result in better understanding and control of their disease. Patients should be advised to avoid known triggers, if feasible, or prepare to prevent or control an exacerbation with appropriate pretreatment if avoidance is not possible. In this review, we describe and discuss a variety of factors for which there is evidence that they cause or exacerbate chronic spontaneous urticaria and angioedema. These potentially exacerbating factors include drugs, food additives, and naturally occurring pseudoallergens, mental stress, and trauma.

Basophil and mast cell activation tests by flow cytometry in immediate drug hypersensitivity: Diagnosis and beyond

Immediate drug hypersensitivity reactions (IDHRs) constitute a significant health issue with serious consequences of diagnostic error. The primary diagnostics to document IDHRs usually consists of quantification of drug-specific IgE (sIgE) antibodies and skin tests. Unfortunately, the positive predictive value (PPV) and negative predictive value (NPV) of these tests are not absolutely, which leaves room for new tests. Over the last two decades, the basophil activation test (BAT), in which ex vivo activation of individual basophils is quantified by flow cytometry, has emerged as a reliable complementary diagnostic to document IDHRs, to explore allergenic recognition, to study cross-reactivity and to monitor therapy. However, the BAT is technically challenging requiring specialized personnel and equipment, fresh samples and the technique is lost as a diagnostic in patients showing a non-responder status of their cells. By consequence, the BAT has still not entered mainstream application. In contrast, mast cell activation tests (MATs) use serum samples that can be frozen, stored, and shipped to a recognized reference centre experienced in mast cell (MC) lines and/or cultures and capable of offering batch testing with necessary quality controls. This review does not only highlight the use of the BAT and MAT as diagnostics in IDHRs, but also outlines the potential of both techniques in further exploring and unveiling the mechanisms that govern drug-induced basophil and MC activation and degranulation.

Clinical value of in vitro tests for the management of severe drug hypersensitivity reactions

Drug hypersensitivity reactions (DHRs) occasionally present with severe cutaneous adverse reactions (SCARs) which result in a high risk of morbidity and mortality. Although SCARs are rare, the occurrence could lead to a significant increase in healthcare and economic burden, especially when more than one possible culprit drug is implicated. Therefore, the accurate identification of the culprit drug(s) is important for correct labeling and subsequent patient education and avoidance. To date, clinical evaluation using causality assessment has limitations because the assessment may be inaccurate due to the overlapping timelines when multiple drugs are initiated/continued. Moreover, drug provocation tests (DPTs) which is the gold standard in diagnosis, are contraindicated, and in vivo skin tests may also be associated with risks of triggering SCAR. The European Network for Drug Allergy recommended that in vitro tests, if available, should be performed before any in vivo tests. Basophil activation tests and lymphocyte transformation tests, could serve as reliable in vitro tests for both immediate and delayed-type DHR. Many academic medical centers with affiliated laboratory services offer these tests in the diagnostic evaluation of SCARs in clinical practice. This not only complements identification of the culprit drug(s), but may also be used to test for potentially non cross-reactive alternatives, hence avoiding DPTs. In this review, we summarize the roles of in vitro tests in identifying the culprit drug(s) in SCARs, issues with utilization and interpretation of test results, and our experience in clinical practice.

Skin Testing to Identify Safe Drugs for Patients with Rocuronium-Induced Anaphylaxis

Among patients who develop anaphylaxis during anesthesia, anaphylaxis caused by a neuromuscular blocking agent has the highest incidence. In patients who developed IgE-mediated anaphylaxis, and cross-reactivity among NMBAs is a concern in subsequent anesthetic procedures. We present a patient who developed rocuronium-induced anaphylaxis in whom the skin prick test (SPT) and intradermal test (IDT) could identify a safe drug to use in the subsequent anesthetic procedure. A 32-year-old female developed anaphylactic shock at the induction of general anesthesia. She recovered by administration of hydrocortisone and epinephrine. Skin tests including the SPT followed by the IDT revealed rocuronium as the drug that caused anaphylaxis and vecuronium as a safe drug to use for the subsequent general anesthesia. She safely underwent surgery with general anesthesia using vecuronium one month after the skin testing. There are not many reports on the effectiveness of the SPT followed by IDT in identifying the causative drug as well as a safe drug to use in the subsequent anesthetic procedure following anaphylaxis during anesthesia. The usefulness of the SPT should be re-evaluated.

Basophil Activation Experiments in Immediate Drug Hypersensitivity: More Than a Diagnostic Aid

BACKGROUND

Correct diagnosis of immediate drug hypersensitivity reactions (IDHRs) can pose a significant challenge, mainly because of the absence of reliable in vitro tests, uncertainties associated with skin testing, and incomplete understanding of the underlying mechanisms.

AIM

To summarize and hypothesize on the potential of basophil activation test (BAT) as a safe aid to explore the mechanistic endotypes of IDHR, to identify antibody recognition sites, and to monitor drug desensitization.

METHODS

A literature search was conducted using the keywords "allergy, basophil activation, CD63, CD203c, diagnosis, drugs, hypersensitivity, flow cytometry"; this was complemented by the authors' own expertise.

RESULTS

At present BAT has mainly been employed as a diagnostic aid. However, evidence is emerging that the technique might also deepen our insights in immune (allergic) and nonimmune (nonallergic) mechanistic processes of IDHR. It is anticipated that BAT might also benefit the identification of antibody recognition sites and benefit our understandings of desensitization strategies.

CONCLUSION

Although the nondiagnostic application of BAT in IDHR is still in its infancy, with increasing employment, we can expect the technique to become a valuable asset to study many domains of IDHR that remain poorly understood.

An EAACI position paper on the investigation of perioperative immediate hypersensitivity reactions

Perioperative immediate hypersensitivity reactions are rare. Subsequent allergy investigation is complicated by multiple simultaneous drug exposures, the use of drugs with potent effects and the many differential diagnoses to hypersensitivity in the perioperative setting. The approach to the investigation of these complex reactions is not standardized, and it is becoming increasingly apparent that collaboration between experts in the field of allergy/immunology/dermatology and anaesthesiology is needed to provide the best possible care for these patients. The EAACI task force behind this position paper has therefore combined the expertise of allergists, immunologists and anaesthesiologists. The aims of this position paper were to provide recommendations for the investigation of immediate-type perioperative hypersensitivity reactions and to provide practical information that can assist clinicians in planning and carrying out investigations.

Chlorhexidine Allergy: On the Rise and Often Overlooked

PURPOSE OF REVIEW

In recent years, the risk of allergy to chlorhexidine is increasingly recognised. In this review, we discuss why the allergy is so easily overlooked and point out several preventative initiatives that can minimise the risk of both chlorhexidine sensitisation and allergy development and accidental re-exposure in patients with chlorhexidine allergy. Testing for chlorhexidine allergy is also discussed.

RECENT FINDINGS

Numerous reports have been published from many different specialties. Symptoms range from mild skin symptoms to life-threatening anaphylaxis. Testing for chlorhexidine allergy is based on skin testing and in vitro testing. Recently, it was found that both skin prick testing and specific IgE have high sensitivities and specificities. This review gives an overview of chlorhexidine allergy with a special focus on preventative initiatives and testing.

Morphine and pholcodine-specific IgE have limited utility in the diagnosis of anaphylaxis to benzylisoquinolines

BACKGROUND

Investigation of immediate hypersensitivity reactions in the perioperative setting involves skin testing and measurement of specific IgE (sIgE) as standard practice. In the case of the neuromuscular blocking agents (NMBAs), the main allergenic epitopes have been shown to be substituted ammonium groups. Commercial assays are available for detection of sIgE to these epitopes using morphine and pholcodine substrates but questions have been raised about the effectiveness of these assays in the diagnosis of benzylisoquinoline anaphylaxis. This study was therefore undertaken to assess the effectiveness of these assays in the diagnosis of hypersensitivity reactions to this group of NMBAs.

METHODS

Analysis was carried out on all available results for patients assessed at the Royal North Shore Hospital Anaesthetic Allergy Clinic during the period June 2009 to June 2016. Standardised intradermal skin tests were performed with a panel of NMBAs. Measurement of sIgE to morphine and pholcodine was performed via the Phadia ImmunoCAP^® system.

RESULTS

For all patients with positive skin test results to NMBAs which included a benzylisoquinoline NMBA (n = 24), 75% exhibited negative sIgE to both morphine and pholcodine. Where patients were reactive to benzylisoquinoline NMBAs alone (n = 12), 100% exhibited negative sIgE results, indicating 0% sensitivity of the assays relative to skin testing, in this subgroup.

CONCLUSION

Use of sIgE testing to morphine and pholcodine in the assessment of NMBA immediate hypersensitivity is a valuable tool particularly in the case of reactions to the aminosteroid NMBAs. However, these assays are unreliable in detecting sensitisation to benzylisoquinoline NMBAs.

Individual risk assessment in the diagnosis of immediate type drug hypersensitivity reactions to betalactam and non-betalactam antibiotics using basophil activation test: a single center experience

BACKGROUND

Drug hypersensitivity reactions of immediate type pose a challenging problem, especially, if standard diagnostic procedures do not lead to conclusive results. The aim of this investigation is to identify, whether basophil activation test (BAT) is able to provide additional benefit in the diagnostic evaluation of immediate type drug hypersensitivity reactions to antibiotics in comparison with the routine allergological diagnostic methods.

MATERIALS AND METHODS

We investigated patients, who presented to the Department of Dermatology and Allergology of the University Hospital of RWTH Aachen in Germany for diagnostic workup of type I allergic reactions to antibiotics during the period from 2009 to 2012. The analysis was performed retrospectively based on patient records. The inclusion criteria were performed standard allergological in vivo diagnostic and a BAT as a part of diagnostic workup.

RESULTS

Eighty-two diagnostic investigations were performed in 52 patients. BAT was positive in 9 of 12 cases with a positive clinical history but negative skin test results. Furthermore, all patients who reported severe drug hypersensitivity reactions (anaphylactic reaction grade 2 and above) showed positive BAT (5/5), while only three of these five cases demonstrated a positive skin testing that led to the conclusion of possible immediate type drug hypersensitivity.

CONCLUSIONS

Although skin tests remain the most important part of the primary diagnostic investigation, BAT is an additional valuable and sensitive in vitro test in the diagnostic procedure of immediate type allergic reactions to antibiotics. However, further standardized investigations are needed in order to calculate exact sensitivity and specificity of this diagnostic tool in both, adult and pediatric populations.

In Vitro Diagnosis of Immediate Drug Hypersensitivity Anno 2017: Potentials and Limitations

Background

For most physicians, quantification of drug-specific immunoglobulin E (drug-sIgE) antibodies constitutes the primary in vitro measure to document immediate drug hypersensitivity reactions (IDHR). Unfortunately, this is often insufficient to correctly identify patients with IgE-mediated IDHR and impossible for non-IgE-mediated IDHR that result from alternative routes of basophil and mast cell activation. In these difficult cases, diagnosis might benefit from cellular tests such as basophil activation tests (BAT).

Aim

The aim was to review the potential and limitations of quantification of sIgE and BAT in diagnosing IDHR. The utility of quantification of serum tryptase is discussed.

Methods

A literature search was conducted using the key words allergy, basophil activation, CD63, CD203c, diagnosis, drugs, hypersensitivity, flow cytometry, specific IgE antibodies; this was complemented by the authors’ own experience.

Results

The drugs that have been most studied with both techniques are β-lactam antibiotics and curarizing neuromuscular blocking agents (NMBA). For sIgE morphine, data are available on the value of this test as a biomarker for sensitization to substituted ammonium structures that constitute the major epitope of NMBA, especially rocuronium and suxamethonium. For the BAT, there are also data on non-steroidal anti-inflammatory drugs (NSAIDs) and iodinated radiocontrast media. For β-lactam antibiotics, sensitivity and specificity of sIgE varies between 0 and 85% and 52 and 100%, respectively. For NMBA, sensitivity and specificity varies between 38.5 and 92% and 85.7 and 100%, respectively. Specific IgE to morphine should not be used in isolation to diagnose IDHR to NMBA nor opiates. For the BAT, sensitivity generally varies between 50 and 60%, whereas specificity attains 80%, except for quinolones and NSAIDs.

Conclusions

Although drug-sIgE assays and BAT can provide useful information in the diagnosis of IDHR, their predictive value is not absolute. Large-scale collaborative studies are mandatory to harmonize and optimize test protocols and to establish drug-specific decision thresholds.

The Value of In Vitro Tests to DiminishDrug Challenges

Drug hypersensitivity reactions have multiple implications for patient safety and health system costs, thus it is important to perform an accurate diagnosis. The diagnostic procedure includes a detailed clinical history, often unreliable; followed by skin tests, sometimes with low sensitivity or unavailable; and drug provocation testing, which is not risk-free for the patient, especially in severe reactions. In vitro tests could help to identify correctly the responsible agent, thus improving the diagnosis of these reactions, helping the physician to find safe alternatives, and reducing the need to perform drug provocation testing. However, it is necessary to confirm the sensitivity, specificity, negative and positive predictive values for these in vitro tests to enable their implementation in clinical practice. In this review, we have analyzed these parameters from different studies that have used in vitro test for evaluating drug hypersensitivity reactions and estimated the added value of these tests to the in vivo diagnosis.

Chlorhexidine allergy in four specialist allergy centres in the United Kingdom, 2009-13: clinical features and diagnostic tests

We describe an observational survey of diagnostic pathways in 104 patients attending four specialist allergy clinics in the United Kingdom following perioperative hypersensitivity reactions to chlorhexidine reactions. The majority were life-threatening. Men undergoing urological or cardiothoracic surgery predominated. Skin prick testing and specific immunoglobulin (sIg)E testing were the most common tests used for diagnosis. Fifty-three per cent of diagnoses were made on the basis of a single positive test. Where multiple tests were performed the sensitivity of intradermal, basophil activation and skin prick testing was 68% (50-86%), 50% (10-90%) and 35% (17-55%), respectively. Seven per cent were negative on screening tests initially, and 12 cases were only positive for a single test despite multiple testing. Intradermal tests appeared most sensitive in this context. Additional sensitization to other substances used perioperatively, particularly neuromuscular blocking agents (NMBA), was found in 28 patients, emphasizing the need to test for possible allergy to all drugs to which the patient was exposed even where chlorhexidine is positive.

Quantification of specific IgE antibodies in immediate drug hypersensitivity: More shortcomings than potentials?

BACKGROUND

For many physicians, quantification of serum drug-specific IgE (sIgE) antibodies constitutes the first measure in the diagnostic approach of immediate drug hypersensitivity reactions (IDHR).

AIM

To review the accuracy and limitations of the main drug-sIgE tests, especially those that are commercially available.

METHODS

A literature search was conducted, using the key-words allergy, diagnosis, drugs, hypersensitivity, specific IgE antibodies; this was complemented by the authors' own experience.

RESULTS

The drugs that have mostly been studied appeared to be β-lactam antibiotics, neuromuscular blocking agents (NMBA) and morphine, the latter as a biomarker for sensitisation to substituted ammonium structures that constitute the major epitope of NMBA. For β-lactams sensitivity and specificity varied between 0-85% and 52-100%, respectively. For NMBA, sensitivity and specificity varied between 38.5-92% and 92-100%, respectively. With respect to sIgE to morphine it appears this drug to be a sensitive biomarker for sensitisation to rocuronium and suxamethonium but not for atracurium. However, sIgE morphine should not be applied in isolation to diagnose IDHR to NMBA nor opiates.

CONCLUSIONS

Although drug-sIgE assay can provide valuable information they should not be performed in isolation to establish correct diagnosis, as their predictive value is not per se absolute. Larger comprehensive studies are urgently required to determine the accuracy of drug-sIgE assays.

Basophil Reactivity as Biomarker in Immediate Drug Hypersensitivity Reactions-Potential and Limitations

Immediate drug hypersensitivity reactions (DHRs) resemble typical immunoglobulin E (IgE)-mediated symptoms. Clinical manifestations range from local skin reactions, gastrointestinal and/or respiratory symptoms to severe systemic involvement with potential fatal outcome. Depending on the substance group of the eliciting drug the correct diagnosis is a major challenge. Skin testing and in vitro diagnostics are often unreliable and not reproducible. The involvement of drug-specific IgE is questionable in many cases. The culprit substance (parent drug or metabolite) and potential cross-reacting compounds are difficult to identify, patient history and drug provocation testing often remain the only means for diagnosis. Hence, several groups proposed basophil activation test (BAT) for the diagnosis of immediate DHRs as basophils are well-known effector cells in allergic reactions. However, the usefulness of BAT in immediate DHRs is highly variable and dependent on the drug itself plus its capacity to spontaneously conjugate to serum proteins. Stimulation with pure solutions of the parent drug or metabolites thereof vs. drug-protein conjugates may influence sensitivity and specificity of the test. We thus, reviewed the available literature about the use of BAT for diagnosing immediate DHRs against drug classes such as antibiotics, radio contrast media, neuromuscular blocking agents, non-steroidal anti-inflammatory drugs, and biologicals. Influencing factors like the selection of stimulants or of the identification and activation markers, the stimulation protocol, gating strategies, and cut-off definition are addressed in this overview on BAT performance. The overall aim is to evaluate the suitability of BAT as biomarker for the diagnosis of immediate drug-induced hypersensitivity reactions.

Clinical and diagnostic features of perioperative hypersensitivity to cefuroxime

INTRODUCTION

The Danish Anaesthesia Allergy Centre (DAAC) investigated 89 adult patients with suspected perioperative cefuroxime-associated hypersensitivity reactions between 2004 and 2013. The goals were to determine whether the time to index reaction after cefuroxime exposure could be used to implicate cefuroxime as the cause of the reactions and explore different test modalities in diagnosing cefuroxime hypersensitivity.

METHOD

Skin tests, in vitro tests, and titrated provocations were used to determine cefuroxime hypersensitivity. Patients were deemed cefuroxime positive on the basis of at least two positive tests and/or a positive provocation.

RESULTS

One or more tests were positive for cefuroxime in 24 of 89 (27.0%) patients. One was only specific IgE positive and was deemed cefuroxime negative. Twenty-three (25.8%) were deemed cefuroxime positive. There were four specific IgE-, 4 histamine release test-, 13 skin test-, and 14 provocation positive patients. There were eight (34.8%) patients who were only provocation positive. Data on time to index reaction after cefuroxime exposure were available for 80 patients (22 in the positive group and 58 in the negative group), 22 of 22 (100%) of positive patients reacted in <15 min vs. only 38 of 58 (65.5%) of negative patients.

CONCLUSION

All patients with confirmed hypersensitivity to cefuroxime reacted within 15 min of administration, but so did 65.5% of Cefuroxime negative patients, making timing of administration an unreliable predictor of causation in the perioperative setting. Provocations were always positive when carried out in skin test positive patients; however, eight patients had positive provocations only, highlighting the need for provocation in skin test negative patients.

In vitro Diagnosis of Immediate Drug Hypersensitivity: Should We Go with the Flow

BACKGROUND

Diagnosis of immediate drug hypersensitivity reactions (IDHRs) is based upon history taking, skin prick or intradermal tests and quantification of specific immunoglobulin E (IgE) antibodies. Unfortunately, this is often insufficient to correctly identify patients with IgE-mediated IDHRs and is impossible in the case of non-IgE-mediated IDHRs. Drug provocation tests (DPT) are considered the 'gold standard' diagnostic but are not always possible, for ethical and practical reasons. Therefore, the validation of new cellular tests such as basophil activation testing (BAT) was necessary. This review focuses on the applications of BAT in IDHRs.

METHODS

A literature search was conducted, using the words basophil, flow cytometry, immediate drug allergy and drugs; this was complemented by the authors' own expertise.

RESULTS

BAT/HistaFlow® is a useful diagnostic tool in IDHRs, mainly used to diagnose allergy to neuromuscular blocking agents (NMBAs), antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs) and iodinated radiocontrast media. Its sensitivity varies between 50 and 60%, and specificity attains 80%, except for with quinolones and NSAIDs.

CONCLUSIONS

The diagnostic utility of BAT (and to lesser extent HistaFlow) has been demonstrated and is mostly applied in IDHRs. However, larger-scale collaborative studies are necessary to optimize test protocols and validate the entry of BAT as a diagnostic instrument in drug allergy.

Immediate-type hypersensitivity drug reactions

Hypersensitivity reactions including anaphylaxis have been reported for nearly all classes of therapeutic reagents and these reactions can occur within minutes to hours of exposure. These reactions are unpredictable, not directly related to dose or the pharmacological action of the drug and have a relatively high mortality risk. This review will focus on the clinical presentation, immune mechanisms, diagnosis and prevention of the most serious form of immediate onset drug hypersensitivity reaction, anaphylaxis. The incidence of drug-induced anaphylaxis deaths appears to be increasing and our understanding of the multiple and complex reasons for the unpredictable nature of anaphylaxis to drugs is also expanding. This review highlights the importance of enhancing our understanding of the biology of the patient (i.e. immune response, genetics) as well as the pharmacology and chemistry of the drug when investigating, diagnosing and treating drug hypersensitivity. Misdiagnosis of drug hypersensitivity leads to substantial patient risk and cost. Although oral provocation is often considered the gold standard of diagnosis, it can pose a potential risk to the patient. There is an urgent need to improve and standardize diagnostic testing and desensitization protocols as other diagnostic tests currently available for assessment of immediate drug allergy are not highly predictive.

In vitro testing for diagnosis of idiosyncratic adverse drug reactions: Implications for pathophysiology

Idiosyncratic drug reactions (IDRs) represent a major health problem, as they are unpredictable, often severe and can be life threatening. The low incidence of IDRs makes their detection during drug development stages very difficult causing many post-marketing drug withdrawals and black box warnings. The fact that IDRs are always not predictable based on the drug's known pharmacology and have no clear dose-effect relationship with the culprit drug renders diagnosis of IDRs very challenging, if not impossible, without the aid of a reliable diagnostic test. The drug provocation test (DPT) is considered the gold standard for diagnosis of IDRs but it is not always safe to perform on patients. In vitro tests have the advantage of bearing no potential harm to patients. However, available in vitro tests are not commonly used clinically because of lack of validation and their complex and expensive procedures. This review discusses the current role of in vitro diagnostic testing for diagnosis of IDRs and gives a brief account of their technical and mechanistic aspects. Advantages, disadvantages and major challenges that prevent these tests from becoming mainstream diagnostic tools are also discussed here.

Predictive value of allergy tests for neuromuscular blocking agents: tackling an unmet need

BACKGROUND

Neuromuscular blocking agents (NMBAs) are a predominant cause of perioperative anaphylaxis in Europe. Diagnosis of NMBA allergy relies upon the careful review of the anaesthetic report complemented with skin tests. Additional diagnostic tests are quantification of specific IgE antibodies (sIgE) and basophil activation test (BAT). However, data on the predictive value of the skin tests, the BAT and the sIgE assays (drug-specific and substituted ammonium structures) are limited or not available, mainly because such exploration requires dangerous NMBA provocation tests.

METHODS

In this study, the predictive value of skin test, BAT and measurement of sIgE to substituted ammonium structures is gathered from a review of anaesthetic records of subsequent surgical procedures with NMBA administration and/or occurrence of perioperative incidents.

RESULTS

We investigated a series of 272 patients with perioperative anaphylaxis, of whom 100 had undergone second general anaesthesia. Negative skin test and negative BAT assisted the selection of alternative NMBA, which were well tolerated in all cases. Five patients with a positive sIgE to rocuronium but with negative skin testing and BAT safely received rocuronium during second anaesthesia. Twelve patients with sIgE reactivity to morphine, but negative skin test and BAT to benzylisoquinolines, tolerated administration of cisatracurium or atracurium. Alternatively, benzylisoquinoline allergy went undetected in the morphine solid-phase assay.

CONCLUSIONS

Skin test and BAT have an excellent negative predictive value in our series. The uneventful re-exposure of rocuronium in patients with an isolated positive sIgE result to rocuronium calls into question the predictive value of this assay and suggests sIgE serology to be less clinically predictive than the functional investigations relying upon activation of mast cells or basophils. The presence of a positive sIgE to substituted ammonium structures such as morphine does not preclude further use of benzylisoquinolines.