T-cell reaction to local anaesthetics: relationship to angioedema and urticaria after subcutaneous application--patch testing and LTT in patients with adverse reaction to local anaesthetics

In Vitro Assays for Diagnosis of Drug-Induced Nonsevere Exanthemas: A Systematic Review and Meta-Analysis

Frequent mislabelled causal relationship between drug hypersensitivity reactions and culprit drugs reinforces the need for an accurate diagnosis. The systematic reviews and meta-analyses of in vitro assays published so far focused on immediate reactions and the most severe delayed reactions, while the most frequent drug-induced delayed reactions-nonsevere exanthemas-have been underestimated. We aim to fill this gap. A systematic review of studies on in vitro assays used in the diagnosis of nonsevere drug-induced delayed reactions was conducted following the methodology of Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy Studies Statement. The EMBASE and PubMed databases were searched. We have included 33 studies from which we extracted the data, then performed meta-analysis where possible, or synthesised the evidence narratively. The quality of the analysed studies was assessed with the QUADAS-2 tool. The tests identified the most frequently were lymphocyte transformation test (LTT), ELISpot, and ELISA. In the meta-analysis carried out for LTT in reactions induce by beta-lactams, the pool estimate of sensitivity and specificity amounted to 49.1% (95% CI: 14.0%, 85.0%) and 94.6% (95% CI: 81.7%, 98.6%), respectively. The studies showed heterogeneity in study design and laboratory settings, which resulted in a wide range of specificity and sensitivity of testing.

Lymphocyte Transformation Test for drug allergy detection: when does it work?

BACKGROUND

The lymphocyte transformation test (LTT) is an in vitro test system for the detection of a sensitization in the context of allergies to drugs. Its reported sensitivity varies largely and seems to be affected by different parameters. In review articles, the average LTT performance was often calculated by combining overall mean sensitivities of various published studies, but without considering different patient characteristics or varying patient numbers per publication.

OBJECTIVE

This meta-analysis aims to investigate the impact of different patient-specific and methodical parameters on the sensitivity of the LTT based on data on the level of the individual patient extracted from single studies.

METHODS

We performed an advanced literature search in Pubmed and screened the identified publications according to previously defined inclusion criteria. In total, individual patient data from 721 patients were extracted from 30 studies. Random-effects meta-regression analyses were performed.

RESULTS

The analysis indicate that the ELISA-based read-out is more sensitive compared to the classical radioactivity method (ELISA: 80% vs. radioactivity: 66%;p=0.084). Interestingly, DRESS/DHISS is associated with a higher probability of a positive LTT test result compared to other investigated clinical phenotypes ("DRESS/DHISS" vs. "bullous reaction"; OR: 2.52;p-value=0.003). Our analysis also revealed an impact of the time to testing period after the occurrence of the allergic event ("<2 weeks" vs. "2 weeks-2 months"; OR: 2.12;p-value=0.034).

CONCLUSION

The read-out method and relevant clinical parameters affect the sensitivity of the LTT. These findings are based on a meta-analysis providing a higher level of evidence than a single study or previous reviews not considering individual patient data.

Lymphocyte transformation test: History and current approaches

Drug-induced hypersensitivity reactions encompass a variety of different clinical phenotypes ranging from harmless rashes to fatal reactions. They can be classified into allergic (i.e. drug allergy) and non-allergic reactions (i.e. non-allergic hypersensitivity). Drug allergies in turn can either be antibody (e.g. IgE) or T cell-mediated. One of the diagnostic tools for the in vitro detection of drug allergy is the lymphocyte transformation test (LTT) which is based on the activation and expansion of the drug-specific memory T cells following co-incubation of the patient's peripheral mononuclear cells (PMBC) with the suspected drug in vitro. The read-out parameter in the classical LTT is T cell proliferation which can be measured as counts per minute following the addition of radiolabeled thymidine to the cell culture. However, in the course of time different modifications of the classical LTT with regard to the read-out parameters and methods have been proposed. Likewise, variations of the LTT platform itself have been described in the literature. This review article describes the development of the classical LTT and its use in the context of drug allergy detection and summarizes the modifications which have been published over time.

Role of in vivo and in vitro Tests in the Diagnosis of Severe Cutaneous Adverse Reactions (SCAR) to Drug

Severe cutaneous adverse reactions (SCAR) are life-threatening conditions including acute generalized exanthematous pustulosis (AGEP), Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Diagnosis of causative underlying drug hypersensitivity (DH) is mandatory due to the high morbidity and mortality upon re-exposure with the incriminated drug. If an underlying DH is suspected, in vivo test, including patch tests (PTs), delayed-reading intradermal tests (IDTs) and in vitro tests can be performed in selected patients for which the suspected culprit drug is mandatory, or in order to find a safe alternative treatment. Positivity of in vivo and in vitro tests in SCAR to drug varies depending on the type of reaction and the incriminated drugs. Due to the severe nature of these reactions, drug provocation test (DPT) is highly contraindicated in patients who experienced SCAR. Thus, sensitivity is based on positive test results in patients with a suggestive clinical history. Patch tests still remain the first-line diagnostic tests in the majority of patients with SCAR, followed, in case of negative results, by delayed-reading IDTs, with the exception of patients with bullous diseases where IDTs are still contra-indicated. In vitro tests have shown promising results in the diagnosis of SCAR to drug. Positivity is particularly high when the lymphocyte transformation test (LTT) is combined with cytokines and cytotoxic markers measurement (cyto-LTT), but this still has to be confirmed with larger studies. Due to the rarity of SCAR, large multi-center collaborative studies are needed to better study the sensitivity and specificity of in vivo and in vitro tests.

H1R mediates local anesthetic-induced vascular permeability in angioedema

Angioedema may occur during local anesthetic (LA) injection in the perioperative period. Histaminergic angioedema is the most common form of angioedema. It has been reported that LA is a potential exogenous ligand for histamine receptor 1 (H₁R). Whether H₁R participates in LA-induced angioedema is still controversial. By using a constructed H₁R high-expressed cell model, siRNA transfection, pharmacologic means, and genetically modified animal models, here we showed that H₁R mediated LA-induced hyperpermeability. LA with uncycled N-methyl scaffold in the side chain (procaine, tetracaine and lidocaine) had a better strength of drug-H₁R affinity than that for LA with cycled N atom (bupivacaine and ropivacaine) by the molecular docking assay and equilibrium dissociation constant (K_D values) obtained from the cell membrane chromatography (CMC) relative standard method. Procaine, tetracaine, and lidocaine triggered big calcium mobilization in H₁R-HEK293 cells and human umbilical vein endothelial cells (HUVECs) but much weaker in NC-HEK293 cells or H₁R knockdown HUVECs. Besides, the results of transendothelial resistance measurement, paracellular flux assay and immunofluorescence showed that procaine induced H₁R-dependent hyperpermeability, which involved in PLCγ/IP3R/PKC, ERK1/2, Akt signaling pathways, downstream vascular endothelial cadherin (VE-cad) destabilization. Furthermore, H₁R gene knockout prevented paw swelling and vascular leakage caused by procaine, tetracaine, and lidocaine in vivo. This study supported a key role of H₁R in LA-induced angioedema, and suggested that in the design of LA structure, the ring formation of the N-methyl scaffold on the side chain can properly avoid the angioedema.

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.

In vitro tests for drug hypersensitivity reactions: an ENDA/EAACI Drug Allergy Interest Group position paper

Drug hypersensitivity reactions (DHRs) are a matter of great concern, both for outpatient and in hospital care. The evaluation of these patients is complex, because in vivo tests have a suboptimal sensitivity and can be time-consuming, expensive and potentially risky, especially drug provocation tests. There are several currently available in vitro methods that can be classified into two main groups: those that help to characterize the active phase of the reaction and those that help to identify the culprit drug. The utility of these in vitro methods depends on the mechanisms involved, meaning that they cannot be used for the evaluation of all types of DHRs. Moreover, their effectiveness has not been defined by a consensus agreement between experts in the field. Thus, the European Network on Drug Allergy and Drug Allergy Interest Group of the European Academy of Allergy and Clinical Immunology has organized a task force to provide data and recommendations regarding the available in vitro methods for DHR diagnosis. We have found that although there are many in vitro tests, few of them can be given a recommendation of grade B or above mainly because there is a lack of well-controlled studies, most information comes from small studies with few subjects and results are not always confirmed in later studies. Therefore, it is necessary to validate the currently available in vitro tests in a large series of well-characterized patients with DHR and to develop new tests for diagnosis.

Nickel sensitization and dietary nickel are a substantial cause of symptoms provocation in patients with chronic allergic-like dermatitis syndromes

Data in literature seem to show that, in patients with contact allergic dermatitis, dietary nickel might be a cause of systemic dermatitis, but little information exists in literature about the role of nickel sensitization and dietary nickel in patients with allergic-like chronic dermatitis syndromes. The prevalence of nickel sensitization in patients with chronic allergic-like, non-IgE-mediated skin diseases, and the possible impact of dietary nickel on symptom provocation and persistence has been assessed in the present retrospective study on a case series of 1726 patients referred to our allergy unit for chronic allergic-like skin diseases. IgE-mediated pathogenesis and other differential diagnoses excluded, patients were patch tested. Nickel-positive patients underwent an elimination diet and double-blind placebo-controlled nickel challenge (DBPCNC) test. A total of 339 (20%) tested nickel-positive. Fifty-two patients (15%) recovered by avoiding sources of nickel contact and 29 (10%) dropped out. Out of the remaining nickel-sensitized patients, 277 (80%) achieved complete or near complete recovery with low-nickel content diet, and 185 of them (89%) were positive to DBPCNC. We conclude that nickel sensitization and dietary nickel seem to be the chief trigger for provocation and persistence of symptoms in an important part (∼11%) of patients with chronic allergic-like dermatitis syndromes.

Hypersensitivity to local anaesthetics--update and proposal of evaluation algorithm

Local anaesthetics (LA) are widely used drugs. Adverse reactions are rare but may be caused by delayed-type hypersensitivity reactions and probably also immediate-type reactions. As it is not always easy to clinically differ between these subtypes, allergy skin testing should be considered. Although numerous test protocols have been published, how patients with hypersensitivity reactions to LA are ideally evaluated remains a topic of discussion. This review attempts to generate a comprehensive update on allergic reactions to LA and to present an algorithm that can be used for the evaluation of patients suspected with immediate- and delayed-type immune reactions. Literature was examined using PubMed-Medline, EMBASE, Biosis and Science Citation Index. Based on the literature, the proposed algorithm may safely and rapidly distinguish between immediate-type and delayed-type allergic immune reactions.

A practical guide to diagnose lesser-known immediate and delayed contrast media-induced adverse cutaneous reactions

The terms "immediate" and "delayed" adverse reactions induced by contrast media (CM) refer to the reactions' onset but do not provide substantial information concerning the clinical manifestation, the potential risk factors, the treatment modalities, or prevention. Because a variety of different reactions caused by different pathophysiological mechanisms may arise immediately or be delayed after CM injection, and because these need different management, the aim of the present paper is to present the clinical features and to exactly characterize lesser-known cutaneous reactions. A thorough knowledge of the clinical features, their adequate treatment, and, possibly, the subsequent diagnostic procedure for preventing recurrence after reexposure to CM would improve patient management.

Allergic reactions occurring during anaesthesia: diagnostic approach

Anaphylactic and anaphylactoid reactions to anaesthetic and associated agents used during the perioperative period have been increasingly reported during the last 3 decades. The frequency of life-threatening hypersensitivity reactions occurring during anaesthesia has been estimated to vary between 1/1.000 and 1/25.0000 procedures, with muscle relaxants being involved in almost three quarters of the cases. The mortality from these reactions is in the range of 3-6%. Nowadays, natural rubber latex also accounts for a significant number of perioperative anaphylaxis, particularly in children. Clinical manifestations do not allow to differentiate between IgE-mediated anaphylaxis and anaphylactoid reactions resulting from non-specific mediator release. Successful management of these patients requires multidisciplinary approach and includes prompt recognition and stabilisation of the acute event by the attending anaesthetist, determination of the responsible agent(s) with avoidance of subsequent administration of incriminated compound(s). The latter is based upon correct identification of the responsible drug and potentially cross-reactive compounds by the allergist and requires a detailed review of the anaesthetic report as well as appropriate in vitro and in vivo allergy tests. At present, the overall performance of skin tests makes them the "gold standard" for diagnosis of muscle relaxant-induced perioperative hypersensitivity reactions. In addition, given their good negative predictive value, skin tests have been proven to be a useful tool to tailor the appropriate therapeutic alternative. For other compounds diagnosis is more difficult but newer techniques such as analysis of in vitro activated basophils can be helpful.

Late-onset allergy-like reactions to X-ray contrast media

PURPOSE OF REVIEW

The purpose of the present review is to describe recent insight into the pathomechanism of the late-onset allergy-like reactions which affect 2-3% of contrast medium-exposed patients, and to give advice regarding prophylactic measures to avoid recurrence of such reactions.

RECENT FINDINGS

It is well recognized that the majority of contrast media-induced late-onset reactions are cutaneous reactions of the maculopapular, urticarial and angioedema types, with occasional occurrence of more serious, bullous eruptions. Recent findings strongly indicate that these reactions are T cell-mediated. The current evidences for this concept are the described clinical symptoms; the high incidence of reactions in interleukin-2-treated patients; the positive results from skin, provocation and lymphocyte transformation testing of affected patients; and the histopathology of skin eruptions and positive skin test sites.

SUMMARY

On the basis of this new knowledge, several prophylactic measures are proposed to avoid repeat reactions in patients with previous late-onset contrast medium reactions. All persons receiving contrast media should be informed that transient skin reactions may develop up to 7 days after contrast medium exposure. Those who experience such reactions should be advised to see an allergist for diagnosis of the reaction. Skin testing with a panel of different contrast media appears to be useful for confirming the presence of an allergic reaction and for identifying alternative contrast media that can be safely used. For undiagnosed persons, a contrast medium that is structurally different from the product that precipitated the reaction should be chosen if re-exposure to contrast media is required. Pretreatment with corticosteroids may also be tried, although its protective effect has not been systematically studied.