Comparison of two basophil activation markers CD63 and CD203c in the diagnosis of amoxicillin allergy

Basophil activation test is a complementary tool in the diagnosis of immediate reactions to platinum salts and taxanes

BACKGROUND

Delabelling pathways offer confirmatory diagnosis and can prevent unnecessary second-line therapies or drug desensitization procedures after chemotherapeutic hypersensitivity reactions (CHT-HSRs). However, these pathways rely on risky in vivo tests. Data on whether in vitro tests could be helpful are scarce. We assessed the role of basophil activation test (BAT) in the diagnosis of HSRs to platin salts (PSs) and taxanes (TXs) in a well-defined population featuring varied endophenotypes and severities of HSRs.

METHODS

We conducted a 3-year-long multicentric, prospective study with 121 suspected-immediate CHT-HSR patients. The allergy workup included clinical history (initial reaction based on Type I, cytokine release syndrome, and mixed phenotype's symptoms and if unable to fit in any of these, as "indeterminate"), skin testing (ST), and drug provocation testing (DPT), provided risk assessment was favorable. Final diagnosis classified patients as "hypersensitive," "non-hypersensitive," or "inconclusive." We performed BAT using CD63 and CD203c as activation markers in patients and controls. Patients underwent DPT regardless of BAT results to prevent bias.

RESULTS

ST positivity significantly correlated with skin involvement, Type I phenotype, cancer recurrence, and lifetime exposures before reactions. DPTs were negative in all indeterminate phenotype patients (p = .02) and those considered low-risk, whereas they were negative in 62% moderate-risk patients. 55% were confirmed as hypersensitive (mainly Type I reactions, p < .0001), 24% as non-hypersensitive (mainly TXs and indeterminate phenotypes), and 21% as inconclusive. BAT showed 79% sensitivity in Type I IgE-mediated reactions to PSs with a high correlation to ST.

CONCLUSIONS

BAT is a promising tool for delabelling and endotyping CHT-HSRs, especially Type I reactions to PSs, possibly identifying patients at risk of positive DPT. ST seems useful in confirming CHT-HSRs, especially PS-induced reactions, and DPT remains the gold standard, being essential even in moderate-risk patients.

Applications of basophil activation test in paediatric allergic diseases

Basophilic granulocytes, containing and releasing histamine after a specific allergy stimulation, are directly involved in IgE-mediated allergic reactions. CD63 is a transmembrane protein of secretory lysosomes of basophils and its upregulation is related with the release of histamine to the extracellular space during IgE-mediated allergic reactions. Basophil activation test (BAT) measures the activation of circulating basophils upon the in vitro stimulation of living blood cells with specific allergens. Such a test is particularly safe and reproducible and has recently emerged as a new promising diagnostic tool for allergic diseases. BAT can be used to diagnose food allergy and represents a promising alternative to oral food challenge tests, especially in children as it is less invasive, safer, and cheaper than the gold standard tests. As a biomarker of tolerance and reactivity, it is also useful to monitor natural resolution and clinical response to immune-modulatory treatments. Regarding drug allergies, BAT is even the only possible applicable diagnostic tool for allergy reactions to some drugs, because of the lack of alternative test, or given that those commonly used are unreliable, or equivocal. Additionally, BAT allows to screen patients with more active urticarial and identify Hymenoptera-allergic patients with negative venom-specific immunoglobulin (Ig)E. In respiratory allergic diseases, BAT can facilitate the diagnosis of local allergic rhinitis and evaluate basophil allergen sensitivity in allergic asthma. Although IgE-sensitization in allergic asthma is usually demonstrated by skin prick test and specific IgE, those tests do not predict the clinical allergy contribution to asthma pathogenesis. To date, the potential of BAT in the diagnostic work-up of allergic diseases is well established, but a better standardization of its use is needed. This narrative review summarizes the state-of-the-art BAT technology and applications in pediatric allergic diseases, focusing on immune-related mechanisms and the BAT real clinical utility.

Increased CD123 + HLA-DR- Granulocytes in Allergic Rhinitis and Influence of Allergens on Expression of Cell Membrane Markers

BACKGROUND

It is reported that CD123 + HLA-DR- cells in PBMC are basophils, and CD203c, CD63, and FcεRI molecules are activation markers of basophils. However, little is known of CD123 + HLA-DR-cells in blood granulocytes.

OBJECTIVE

To investigate the presence of CD123 + HLA-DR- cells in the blood granulocytes and peripheral PBMC of patients with allergic rhinitis (AR), as well as the impact of allergens on the cell membrane markers of basophils.

METHODS

Flow cytometry was used to detect the expression of the membrane molecules.

RESULTS

While CD123 + HLA-DR- PBMCs are representative of basophils, their presence did not significantly change in patients with AR. In contrast, both the percentage and number of CD123 + HLA-DR- granulocytes, which make up only up to 50% of basophils, were significantly increased in patients with seasonal (sAR) and perennial AR (pAR). CD63+, CD203c+, and FcεRIα+ cells within CD123 + HLA-DR- granulocytes also showed enhanced activity in patients with AR. Allergen extracts from house dust mite allergen extract (HDME) and Artemisia sieversiana wild extract further increased the number of CD123 + HLA-DR- cells in granulocytes of sAR and pAR patients, as well as in PBMCs of pAR patients.

CONCLUSIONS

The use of CD123 + HLA-DR- granulocytes and PBMC may not be sufficient for diagnosing AR. Allergens could potentially contribute to the development of AR by influencing the number of CD123 + HLA-DR- cells, as well as the expression of CD63, CD203c, and FcεRIαin these cells.

Involvement of autologous myeloid dendritic cells in the evaluation of immediate hypersensitivity reactions to betalactams

BACKGROUND

Amoxicillin (AX) and clavulanic acid (CLV) are the betalactam antibiotics (BLs) most used to treat bacterial infections, although they can trigger immediate hypersensitivity reactions (IDHRs). The maturation analysis of monocyte-derived dendritic cells (moDCs) and their capacity to induce proliferative response of lymphocytes are useful to test the sensitisation to a drug, although without optimal sensitivity. Nevertheless, this can be improved using directly isolated DCs such as myeloid DCs (mDCs).

METHODS

mDCs and moDCs were obtained from 28 allergic patients (AP), 14 to AX, 14 to CLV and from 10 healthy controls (HC). The expression of CCR7, CD40, CD80, CD83, and CD86 was analysed after stimulation with both BLs. We measured the capacity of these pre-primed DCs to induce drug-specific activation of different lymphocyte subpopulations, CD3+, CD4+, CD8+, CD4+Th1, and CD4+Th2, by flow cytometry.

RESULTS

Higher expression of CCR7, CD40, CD80, CD83, and CD86 was observed on mDCs compared to moDCs from AP after stimulating with the culprit BL. Similarly, mDCs induced higher proliferative response, mainly of CD4+Th2 cells, compared to moDCs, reaching up to 67% of positive results with AX, whereas of only 25% with CLV.

CONCLUSIONS

mDCs from selective AP efficiently recognise the culprit drug which trigger the IDHR. mDCs also trigger proliferation of lymphocytes, mainly those with a Th2 cytokine pattern, although these responses depend on the nature of the drug, mimicking the patient's reaction.

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.

Performance Characteristics of Basophil Activation Tests for Diagnosing Penicillin Allergy: A Meta-Analysis

BACKGROUND

Approximately 10% of the global population identify themselves as penicillin allergic, yet 90% are not truly allergic and could safely tolerate penicillin. There is no simple way to identify these people. Current in vitro diagnostics include specific immunoglobulin E (with a sensitivity of 19% and specificity of 97%) and a basophil activation test (BAT) with undefined sensitivity and specificity.

OBJECTIVE

To define the sensitivity and specificity of BAT in the diagnosis of penicillin allergy METHODS: We searched PubMed and EMBASE from inception to April 2, 2023, for original studies evaluating the performance characteristics of BAT for penicillin allergy in adults. Study selection, data extraction, risk of bias, assessment with QUADAS-2 tool, certainty assessment with Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology were performed independently, in duplicate. Meta-analysis was performed using Reitsma methodology.

RESULTS

Twenty-two studies fulfilled the inclusion criteria. Twelve used the same positive threshold giving a summary point sensitivity 51% (95% confidence interval [95% CI]46%-56%) and specificity 89% (95% CI 85%-93%). Significant risk of bias was identified owing to patient selection. GRADE certainty of evidence rated sensitivity very low due to imprecision and specificity as low. There was great heterogeneity in methods used. Use of 1,000 basophils per test did not improve performance above 500 basophils.

CONCLUSIONS

BAT sensitivity is highly variable across studies and remains too low to be considered as a routine element of clinical practice. BAT specificity is not as good as specific immunoglobulin E in penicillin allergy diagnosis. Significant further work is required in this field before clinical application of BAT in routine practice.

Real-Life Utility of Basophil Activation Test in the Diagnosis of Immediate Hypersensitivity Drug Reactions

INTRODUCTION

The basophil activation test (BAT) is a flow cytometry laboratory technique that assesses the level of activation indicators expressed on the surface of basophils. We conducted a real-life study in a prospective cohort of patients with reported drug hypersensitivity reactions to determine the true relevance of BAT as a diagnostic tool for assessing immediate hypersensitivity reactions to medicines.

METHODS

We prospectively assessed individuals with clinical suspicion of immediate hypersensitivity reactions to drugs over a 2-year period. The allergological evaluation was carried out in accordance with European Academy of Allergy and Clinical Immunology (EAACI) guidance. All patients underwent BAT using the activation marker CD63.

RESULTS

In total 13 patients with 54 reported immediate drug hypersensitivity reactions to medications were included in this study. Twelve were female (92.3%) and one was male (7.70%). The mean ± SD age of the patients was 47.31 ± 19.94 years. Antibiotics were tested in 35.2% (19/54) of patients, corticosteroids in 24.1% (13/54), iodinated contrast medium in 14.8% (8/54), and NSAIDs in 5.6% (3/54). There was no correlation between the BAT results and the age of patients, gender, type of medication, or time interval between the allergic reaction and BAT procedure. The sensitivity of BAT 5% CD63+ basophils to drugs was 97.6%, specificity was 96% for drug allergies, positive predictive value (PPV) was 94.3%, and negative predictive value (NPV) was 95.2%.

CONCLUSIONS

The sensitivity of BAT for drug allergies is limited, but it can nevertheless be very helpful before contemplating provocation testing in cases of life-threatening drug allergies where patients cannot be rechallenged or in cases of medications for which no other tests are available or their results are ambiguous.

Diagnosis of immediate reactions to amoxicillin: Comparison of basophil activation markers CD63 and CD203c in a prospective study

BACKGROUND

Amoxicillin (AX) combined or not with clavulanic acid (CLV) is frequently involved in IgE-mediated reactions. Drug provocation test (DPT) is considered as the gold standard for diagnosis, although contraindicated in high-risk patients. Basophil activation test (BAT) can help diagnose immediate reactions to beta-lactams, although controversy exists regarding the best activation marker. We have performed a real-life study in a prospective cohort to analyze the real value of BAT as diagnostic tool and the best activation marker, CD63 and CD203c, for the evaluation of immediate reactions to these drugs.

METHODS

We prospectively evaluated patients with a clinical suspicion of immediate reactions after AX or AX-CLV administration during a 6-year period. The allergological work-up was done following the EAACI recommendations. BAT was performed in all patients using CD63 and CD203c as activation markers.

RESULTS

In AX-allergic patients, both activation markers, CD63 and CD203c, showed similar SE values (48.6% and 46.7%, respectively); however, specificity was of 81.1% and 94.6%, respectively, with CD203c showing good positive predictive value and like-hood ratio. In CLV-allergic patients, CD203c showed higher SE (50%) than CD63 (42.9%), maintaining the same value of SP (80%). Combining the results of both markers can slightly increase the sensitivity (51.4% for AX and 54.8% for CLV), although decreasing the specificity (79.7% and 73%, respectively). Interestingly, all patients with an anaphylactic shock showed a positive BAT to CLV using CD203c.

CONCLUSIONS

BAT using CD203c showed a good confirmatory power, especially for AX allergy. Placing BAT as a first step in the diagnostic procedure can help reduce the need of performing a complete allergological work-up in 46.6% of patients, diminishing the risk of reinducing allergic reactions.

Standardizing In Vitro β-Lactam Antibiotic Allergy Testing with Synthetic IgE

The global prevalence of β-lactam allergy poses a major challenge in administering first-line antibiotics, such as penicillins, to a significant portion of the population. The lack of β-lactam IgE antibody pools with defined selectivity hampers the standardization and validation of in vitro assays for β-lactam allergy testing. To address this limitation, this study introduces a synthetic IgE specific to β-lactam antibiotics as a valuable tool for drug allergy research and diagnostic tests. Using phage display technology, we constructed a library of human single-chain antibody fragments (scFv) to target the primary determinant of amoxicillin, a widely used β-lactam antibiotic. Subsequently, we produced a complete human synthetic IgE molecule using the highly efficient baculovirus expression vector system. This synthetic IgE molecule served as a standard in an in vitro chemiluminescence immunoassay for β-lactam antibiotic allergy testing. Our results demonstrated a detection limit of 0.05 IU/mL (0.63 pM), excellent specificity (100%), and a four-fold higher clinical sensitivity (73%) compared to the in vitro reference assay when testing a cohort of 150 serum samples. These findings have significant implications for reliable interlaboratory comparison studies, accurate labeling of allergic patients, and combating the global public health threat of antimicrobial resistance. Furthermore, by serving as a valuable trueness control material, the synthetic IgE facilitates the standardization of diagnostic tests for β-lactam allergy and demonstrates the potential of utilizing this synthetic strategy as a promising approach for generating reference materials in drug allergy research and diagnostics.

Diagnostic utility of basophil CD203c expression in β-lactam allergy

Background: A diagnosis of immunoglobulin E (IgE) mediated reactions to β-lactam (BL) antibiotics is still challenging because of the limited availability of skin-prick test (SPT), and standardization issues, particularly with newer BLs, are still ongoing. Because encouraging data are increasingly emerging in the use of basophil activation tests in the diagnosis of IgE-mediated drug hypersensitivity reactions, in this study, we aimed to determine CD203c expression, a basophil surface marker, in the diagnosis of IgE-mediated hypersensitivity to BL antibiotics. Methods: This study included two groups of subjects. The first group (group 1) (n = 20) included patients with a diagnosis of IgE-mediated allergy to BLs as confirmed through STs or drug provocation tests, and the control group consisted of healthy volunteers (group 2) (n = 24). Expression of CD203c by flow cytometry was studied in samples stimulated by two different concentrations of six different BL antibiotics. A stimulation index ≥ 2 was considered a positive response. Results: The study groups had comparable age and sex distribution. In the entire group, the sensitivity and specificity of CD203c were 29.4% (5 out of 17) and 82.6% (19 out of 23), respectively. When considering the single reactors, two among four patients who were allergic to amoxicillin demonstrated upregulation of CD203c with amoxicillin, which makes 50% sensitivity. The specificity was 100%. Conclusion: Our data demonstrated that assessment of CD203c in the diagnosis of IgE-mediated reactions to BLs provided encouraging results, particularly with amoxicillin allergy. However, this finding needs to be verified in a larger number of cases.

Basophil Activation Test Shows Poor Sensitivity in Immediate Amoxicillin Allergy

BACKGROUND

In light of the pandemic of spurious penicillin allergy, correct diagnosis of amoxicillin (AX) allergy is of great importance. The diagnosis of immediate hypersensitivity reactions relies on skin tests and specific IgE, and although reliable, these are not absolutely predictive. Therefore, drug challenges are needed in some cases, which contain the risk of severe reactions. Safe in vitro diagnostics as an alternative for the drug challenge in the diagnostic workup of AX allergy would be more than welcome to fill this gap. In this respect, the basophil activation test (BAT) has shown potential, but its clinical reliability is doubtful.

OBJECTIVE

To investigate the reliability of the BAT to AX and determining its exact place in the diagnostic algorithm of AX allergy.

METHODS

BAT for AX was performed in 70 exposed control individuals and 66 patients diagnosed according to the European Academy of Allergy and Clinical Immunology guidelines for AX allergy. Upregulation of both CD63 and CD203c was flow-cytometrically assessed.

RESULTS

Analyses revealed that 1370 μmol/L and 685 μmol/L were the most discriminative stimulation concentrations for CD63 and CD203c upregulation, respectively, and a diagnostic threshold of 9% for positivity for both markers was identified. At these concentrations, sensitivity and specificity for CD63 upregulation were 13% and 100%, respectively, and for CD203c upregulation, 23% and 98%.

CONCLUSIONS

BAT with dual analysis of CD63 and CD203c is of poor performance to document AX allergy. The sensitivity is too low to let it occupy a prominent role in the diagnostic algorithm.

Towards standardizing basophil identification by flow cytometry

Background

Basophils normally make up <2% of the white blood cells (WBC). There is no clear consensus for basophil identification by flow cytometry. The increased demand for basophil activation test (BAT) to identifying and monitoring allergic patients highlights the need for a standardized approach to identify basophils.

Methods

Using flow cytometry we analyzed whole blood stained with antibodies against: IgE, CD123, CD193, CD203c, CD3, HLADR, FcɛRI, CRTH2 and CD45. We examined unstimulated blood as well as blood stimulated with Anti-IgE and fMLP. Finally, we compared the results to a complete blood count (CBC) from an FDA approved hematological analyzer.

Results

Basophil identification relying on just one surface marker performed worse than approaches utilizing two identification markers. The percentage of basophils from WBC determined by flow cytometry results had a good correlation with the CBC results even though the CBC results were generally higher. Stimulating whole blood with the basophil activators did not interfere with the basophil identification markers.

Conclusion

In flow cytometry assays, two surface markers should be used for identifying basophils and if a very pure basophil fraction is desired a third marker can be considered. In our hands the approaches that included CD123 in combination with either CD193, HLADR^negative or FcɛRI performed the best.

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.

Increased expressions of CD123, CD63, CD203c, and Fc epsilon receptor I on blood leukocytes of allergic asthma

Background : Altered basophil identification markers have been discovered to associate with allergic asthma (AA) in recent years. However, little is known about the expression of basophil markers in blood granulocytes. Aim: To parallel test blood basophils in peripheral blood mononuclear cell (PBMC) and granulocyte populations of patients with AA and AA combined with allergic rhinitis (ARA) Methods: The expressions of surface molecules were determined via flow cytometry. CD123 expressing cells in blood were isolated using a cell sorting technique, and mouse AA models were employed for in vivo study. Results: The numbers of CD123+HLA-DR- cells in the granulocytes of AA and ARA patients markedly increased. However, only 49.7% of CD123+HLA-DR- cells in granulocytes and 99.0% of CD123+HLA-DR- cells in PBMCs were basophils. Almost all CD123+HLA-DR- cells expressed CD63 regardless in granulocytes or PBMC. The numbers of CD63, Fc epsilon receptor I (FcεRI), and CD203c expressing cells markedly enhanced in CD123+HLA-DR- granulocytes of AA and ARA patients. Mean fluorescence intensity (MFI) of CD63 and CD203c expressions on CD123+HLA-DR- PBMC and granulocytes of AA and ARA patients dramatically elevated. House dust mite extract (HDME) and Artemisia sieversiana wild allergen extract (ASWE) enhanced the numbers of CD63+CD123+HLA-DR- granulocytes and PBMC and the MFI of CD203c expression on CD123+HLA-DR- granulocyte of AA and ARA patients. Histamine, tryptase, and PGD2 enhanced proportions of CD123+ KU812 cells. ASWE- and HDME-induced AA mice showed upregulated CD63 expression on basophils. In conclusion, upregulated expressions of CD123, CD203c, CD63, and FcεRIα in PBMC and granulocytes of patients with AA and ARA suggest that CD123+HLA-DR- cells may contribute to the development of AA and ARA.

Exploring the role of basophil activation test in diagnosis of Dermatophagoides farinae sensitization and evaluation of therapeutic efficacy of subcutaneous immunotherapy in children

OBJECTIVE

It aims to detect basophil activation ratio (%CD63⁺ ) in peripheral blood of children with allergic asthma and rhinitis by using Flow cytometry (FCM) , so as to analyze the application values and clinical relevance of the Basophil Activation Test (BAT) in diagnosis of Dermatophagoides farinae (Derf) sensitization and monitoring therapeutic efficacy of subcutaneous immunotherapy (SCIT).

METHODS

It was a prospective study. From the newly diagnosed children with asthma and rhinitis in our pediatric clinic, 39 patients diagnosed Derf sensitization and 15 patients not allergic to Derf were enrolled; another 4 healthy children were taken as control group. Using Derf extracts in concentration of 1 μg/ml, 10 μg/ml and 100 μg/ml as the stimulus, BAT results were expressed as %CD63⁺ in diagnosis of Derf sensitization and its correlation with skin prick tests (SPT), serum total IgE (tIgE), specific IgE (sIgE), sIgE/tIgE, specific IgG4 (sIgG4), FEV1%pred in pulmonary ventilation function, exhaled nitric oxide (FeNO), children asthma control test (C-ACT) and visual analogue scale (VAS) were observed. In sensitization group, %CD63⁺ , sIgG4 and clinical indicators were detected again from patients who had received SCIT to analyze their internal connections.

RESULTS

The average levels of %CD63⁺ in three concentrations showed an increasing concentration-dependent trend overall. %CD63⁺ in sensitization group was significantly higher than that in the other two groups. The analysis of ROC for Derf sensitization showed the area under the curve (AUC) for BAT in three concentrations were higher than that for sIgE whose AUC is 0.893. %CD63⁺ was positively correlated with SPT grade, sIgE, sIgE/tIgE and VAS, and negatively correlated with C-ACT. In patients receiving SCIT, %CD63⁺ became lower and sIgG4 level became higher than pretreatment. There was no obvious change in sIgG4 in those who hadn't received SCIT.

CONCLUSIONS

BAT is a reliable and non-invasive tool for diagnosis of Derf sensitization in children with asthma and rhinitis. CD63-based BAT has clinical value to monitor outcome of SCIT, and the change of basophil activation is inherently related to induction of sIgG4.

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.

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.

BAT in the Diagnosis of Drug Allergy: a Novel Tool in Clinical Daily Practice?

PURPOSE OF REVIEW

The aim of this study is to critically review the relevant literature published on basophil activation test, presenting the current knowledge and future perspectives.

RECENT FINDINGS

Basophil activation test (BAT) results varied accordingly to the class of the drug studied, and have promising results in immediate hypersensitivity reactions to pyrazolone (selective reactors), neuromuscular blockers, beta-lactams, and platinum compounds, all examples of classical IgE-mediated hypersensitivity drug reactions. Currently, BAT is applied in research settings, but based in the results of our review, the test can be considered as a diagnostic tool for daily practice for selected patients and selected drugs, when the test is available, particularly for patients who experienced severe reactions and when diagnosis cannot be stablished by serum-specific IgE and skin testing, in order to avoid unnecessary drug provocations tests.

Evaluation of basophil activation caused by transgenic rice seeds expressing whole T cell epitopes of the major Japanese cedar pollen allergens

Background

Japanese cedar (JC) pollinosis is a serious type I allergic disease in Japan. Although subcutaneous immunotherapy and sublingual immunotherapy have been applied to treat JC pollinosis, high doses of allergens may cause IgE-mediated allergic reactions. The transgenic rice seeds that contain genetically modified Cry j 1 and Cry j 2, the two major allergens of JC pollen, have been developed as candidates for oral immunotherapy. Although the antigens in the transgenic rice seeds (Tg-rice seeds) were engineered such that they decrease binding ability with IgE and they are of insufficient length to cross-link IgE on the surface of mast cells or basophils, the safety of Tg-rice seeds for patients with JC pollinosis was unclear.

Methods

To verify the safety of Tg-rice seeds in terms of allergies, we investigated the percentage of activated basophils induced by Tg-rice seed extract in the basophil activation test. Blood samples from 29 patients with JC pollinosis were collected. Tg-rice seed extract, non-transgenic wild-type rice seed extract, and Cry j 1 and Cry j 2 were mixed with the blood with reagents. The percentage of activated basophils was assessed by CD203c expression, a basophil activation marker.

Results

The percentage of activated basophils after the stimulation with Tg-rice seed extract was 4.5 ± 1.6% (mean ± SD) compared with 62.9 ± 20.2% after Cry j 1- and Cry j 2-stimulation (difference 58.4%, P < 0.001, 95% confidence interval 51.0–65.9%).

Conclusions

The results will contribute to the safety of Tg-rice seeds in terms of allergies.

Causal Relationship Between Anti-TPO IgE and Chronic Urticaria by In Vitro and In Vivo Tests

PURPOSE

Immunoglobulin (Ig) E autoantibodies against thyroid antigens such as thyroid peroxidase (TPO) have been demonstrated in chronic spontaneous urticaria (CSU) patients in higher frequency than healthy subjects. However, if these IgE autoantibodies can trigger urticaria is still a matter of study. The aim of this study was to investigate the relationship between concomitant IgE autoantibodies against thyroid antigens in CSU.

METHODS

Patients with CSU, healthy subjects and patients with autoimmune thyroid disease (ATD) were recruited. Total IgE and specific anti-TPO IgE and IgG were assessed in all subjects. The basophil activation test and skin tests with TPO were performed to demonstrate whether this antigen could selectively induce urticaria reaction in subjects with positive anti-TPO IgE.

RESULTS

Anti-TPO IgE was present in all 3 groups (CSU: 34.0%, ATD: 16.6%, healthy subjects: 8.1%). Anti-TPO IgE levels were higher in CSU patients, whereas anti-TPO IgG were higher in ATD patients. After exposure to TPO, CD203c expression from patients with CSU and anti-TPO IgE significantly increased in comparison to the other groups; 33.0% vs. 14.0% in ATD patients and 9.0% in control subjects (P < 0.05). Skin reactions with TPO were higher in patients with CSU according to the intradermal (CSU: 18.0%, ATD: 3.3%, control: 8.0%) and skin prick tests (12.0%, 0%, 0%, respectively). Passive transfer of anti-TPO IgE from a CSU patient to the skin of control subjects without anti-TPO IgE induced a positive skin reaction.

CONCLUSIONS

Anti-TPO IgE is not a specific biomarker for CSU. However, IgE against TPO plays a pathogenic role in inducing effector cell activation and skin exacerbation in some patients with CSU.

Prueba de activación de basófilos: aspectos técnicos, metodológicos y su utilidad clínica

Introducción. La prueba de activación de basófilos (PAB) se considera una técnica confiable y segura para el diagnóstico de problemas alérgicos.Objetivo. Profundizar en el estado del arte de la PAB y su utilidad clínica.Materiales y métodos. Se realizó una revisión narrativa de la literatura mediante la búsqueda electrónica en las bases de datos y metabuscadores Ovid Medline, Google Scholar y PubMed, sin limitar la búsqueda por fecha, idioma o tipo de artículo. Se buscaron artículos sobre los detalles técnicos de la PAB y su utilidad clínica en el manejo de las enfermedades alérgicas.Resultados. De los marcadores de activación, CD63 ha sido el más estudiado y es el que mejor representa un evento de degranulación anafiláctica, mientras que CD203c es representativo de varias formas de degranulación. La superioridad de uno sobre otro como prueba diagnóstica depende del problema alérgico estudiado. En cuanto a los métodos de detección de basófilos, su selección con un único marcador, CCR3, se propone como una opción con buena relación de costo-efectividad.Conclusiones. La PAB es una herramienta prometedora para evaluar en clínica las reacciones alérgicas de forma segura. Es necesario una mayor estandarización de protocolos para obtener resultados más reproducibles.

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.

Pros and Cons of Clinical Basophil Testing (BAT)

PURPOSE OF REVIEW

We review basophil testing by flow cytometry with an emphasis on advantages and disadvantages.

RECENT FINDINGS

There are many tools available to assess the presence and severity of allergic diseases in patients. For 50 years, peripheral blood basophils have been used as tools to study these diseases. It is a very accessible cell that binds IgE antibody and secretes the classical mediators responsible for the symptoms of allergic reactions. In the last decade, an even more accessible methodology, using flow cytometry, has been developed to enhance the ability to use basophils for both mechanistic and clinical diagnostics. Basophil testing has been included in diagnostics for different forms of allergies as well as to monitor disease status. A variety of studies have begun to establish both precise methods and their clinical relevance for disease diagnosis, but there remain some important questions on how to take optimal advantage of the behaviours of basophils.

In Vitro Diagnostic Testing for Antibiotic Allergy

Allergy to antibiotics is an important worldwide problem, with an estimated prevalence of up to 10% of the population. Reaction patterns for different antibiotics have changed in accordance with consumption trends. Most of the allergic reactions to antibiotics have been reported for betalactams, followed by quinolones and macrolides and, to a lesser extent, to others, such as metronidazole clindamycin and sulfonamides. The diagnostic procedure includes a detailed clinical history, which is not always possible and can be unreliable. This is usually followed by in vivo, skin, and drug provocation tests. These are not recommended for severe, potentially lifethreaten reactions or for drugs that are known to produce a high rate of false positive results. Given the limitations of in vivo tests, in vitro test can be helpful for diagnosis, despite having suboptimal sensitivity. The most highly employed techniques for diagnosing immediate reactions to antibiotics are immunoassays and basophil activation tests, while lymphocyte transformation tests are more commonly used to diagnose non-immediate reactions. In this review, we describe different in vitro techniques employed to diagnose antibiotic allergy.

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.

Increased cis-to-trans urocanic acid ratio in the skin of chronic spontaneous urticaria patients

Increased filaggrin expression was found to be correlated with severity scores in chronic spontaneous urticaria (CSU); however, the role of filaggrin breakdown products (FBPs) in CSU has not been studied. We collected stratum corneum (SC) specimens from the volar forearms of 10 CSU patients, 10 AD patients, and 10 healthy normal controls (NCs) and measured contents of FBPs (pyrrolidone carboxylic acid [PCA] and urocanic acid [UCA]) using UPLC-MS/MS, transepidermal water loss (TEWL) and epidermal pH. Compared to NCs, cis-UCA level was increased in CSU lesions (P < 0.05) and decreased in AD lesions (P < 0.01). The cis-to-trans-UCA ratio in SC specimens from CSU patients was significantly greater than those from AD and NC subjects. AD lesions had lower FBP and PCA contents compared to NC skin (both P < 0.001), and higher TEWL and pH compared to CSU lesions. Moreover, cis-UCA, but not trans-UCA, enhanced the IgE-mediated basophil activation, as well as IgE- and calcium-mediated degranulation of LAD-2 cells, in a dose-dependent manner. These findings suggest that increased cis-to-trans UCA ratio in the epidermis is a distinct feature of CSU, which could enhance mast cell degranulation. Modulation of cis-UCA may be a potential target for skin diseases associated with IgE-mediated mast cell degranulation.

Evolution of diagnostic approaches in betalactam hypersensitivity

INTRODUCTION

Betalactams are the most widely used drugs against infections and the primary cause of antibiotic hypersensitivity reactions. Reaction patterns for different betalactams have been changing in accordance with consumption trends, and vary among countries. As a consequence, in vivo and in vitro tests have had to change with to keep up with new tendencies. Areas covered: This review is focused on advances in betalactam hypersensitivity diagnosis. Changes in in vivo methods have been limited to the inclusion of new haptens. In contrast, major progress has been achieved for in vitro tests since the 1960s, from the first description of immunoassays, the basophil activation test and the lymphocyte transformation test, to the more sophisticated assays developed in last years. Expert commentary: Issues with diagnosis are related to test sensitivity. In vivo tests show higher sensitivity, however they can be risky, especially in severe and life-threatening reactions. Therefore, we believe that in vitro tests should be the preferred method. Current efforts are under way to enhance their sensitivity. Only multidisciplinary approaches involving immunology, proteomics, nanotechnology and chemistry can help us to fully understand conjugate structures and mechanisms involved in hypersensitivity reactions to betalactams, and consequently lead to advances in in vitro methods.

The Evolution of Human Basophil Biology from Neglect towards Understanding of Their Immune Functions

Being discovered long ago basophils have been neglected for more than a century. During the past decade evidence emerged that basophils share features of innate and adaptive immunity. Nowadays, basophils are best known for their striking effector role in the allergic reaction. They hence have been used for establishing new diagnostic tests and therapeutic approaches and for characterizing natural and recombinant allergens as well as hypoallergens, which display lower or diminished IgE-binding activity. However, it was a long way from discovery in 1879 until identification of their function in hypersensitivity reactions, including adverse drug reactions. Starting with a historical background, this review highlights the modern view on basophil biology.

Exploratory analysis of CD63 and CD203c expression in basophils from hazelnut sensitized and allergic individuals

Background

Sensitization to hazelnut (HN) is frequent and requires clarification to determine whether this sensitization is clinically relevant. The aim of this study was to investigate basophil activation profiles in HN-sensitized and allergic subjects.

Methods

Basophil activation was determined by flow cytometric analyses of CD63 and CD203c expression using several HN allergen concentrations. Depending on their clinical reaction pattern, an oral allergy symptom group (OAS, n = 20), a systemic reaction group (n = 12) and a sensitized group without clinical symptoms (n = 20) were identified. Additionally, 10 non-allergic and non-sensitized individuals served as controls.

Results

CD63 and CD203c expression differed between allergic (OAS and systemic group) and sensitized subjects. The HN concentration required to activate 30% of CD203c⁺ basophils [effective concentration (EC)30] was significantly higher in sensitized versus the allergic group (p = 0.0089). This was more pronounced when the basophil allergen threshold sensitivity (CD-sens) was calculated (CD63: p = 0.018; CD203c: p = 0.009).

Conclusion

Our data indicate that the basophil activation test may provide information to better distinguish between sensitized and allergic subjects if several allergen concentrations are considered. CD203c expression displayed a better discrimination compared to CD63; therefore, its diagnostic value might be superior compared with CD63.

Electronic supplementary material

The online version of this article (doi:10.1186/s13601-016-0134-7) contains supplementary material, which is available to authorized users.

The Basophil Activation Test Is Safe and Useful for Confirming Drug-Induced Anaphylaxis

The basophil activation test (BAT) has been suggested as a complementary method for diagnosing drug allergies. The aim of this study was to evaluate the clinical utility of this test in patients with drug-induced anaphylaxis. In total, 19 patients, all of whom had a history of moderate to severe anaphylaxis, were enrolled. None of the causative drugs had available in vitro tests or reliable skin tests; these drugs included, among others, first and second-generation cephalosporins, H2 blockers, and muscle relaxants. The BAT yielded positive results in 57.9% of the cases, which was similar those results of skin prick and intradermal tests (42.1% and 57.9%, respectively). When basophils were double labelled with CD63 and CD203c, both of which are basophil activation markers, the positive rate was increased from 57.9% to 73.7%. Therefore, the results of this study confirm that the BAT is a quick, reliable, and safe diagnostic tool for patients with drug-induced anaphylaxis.

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.

Hypersensitivity to fluoroquinolones: The expression of basophil activation markers depends on the clinical entity and the culprit fluoroquinolone

Although fluoroquinolones (FQs) are generally well-tolerated antibiotics, increasing numbers of hypersensitivity reactions have been reported. These can be evaluated in vitro by basophil activation tests (BATs); however, sensitivity is not optimal. Many factors could influence sensitivity such as basophil activation markers. The objective of this study was to evaluate the influence of 2 different activations markers, CD63 and CD203c, on the sensitivity of BAT to FQ. We studied 17 patients with immediate allergic reactions to FQ. BAT was performed with moxifloxacin and ciprofloxacin using CD193 (CCR3) for basophil selection and CD203c or CD63 as activation markers. Stimulation with ciprofloxacin induced a significantly higher expression of CD63 in ciprofloxacin-allergic patients compared to moxifloxacin-allergic patients (P = 0.002). In patients allergic to moxifloxacin with anaphylactic shock, we have observed an increase in the percentage of cells that upregulate CD203c, whereas patients with anaphylaxis preferentially upregulate CD63. The best sensitivity-specificity was obtained using a cutoff of 3 and the culprit FQ, using CD203c for moxifloxacin-allergic patients (sensitivity = 36.4%; specificity = 94.4%), and CD63 for ciprofloxacin-allergic patients (sensitivity = 83.3%; specificity = 88.9%). A negative correlation was found between the upregulation of CD63 and CD203c and the time interval between the reaction occurrence and the performance of the test (Spearman r = -0.446; P < 0.001 for CD63 and Spearman r = -0.386; P < 0.001 for CD203c). The performance of BAT for FQ allergy must be optimized for each drug, taking into account possible differences in the stimulation mechanism that leads to the upregulation of different activation markers.

Current and future biomarkers in allergic asthma

Diagnosis early in life, sensitization, asthma endotypes, monitoring of disease and treatment progression are key motivations for the exploration of biomarkers for allergic rhinitis and allergic asthma. The number of genes related to allergic rhinitis and allergic asthma increases steadily; however, prognostic genes have not yet entered clinical application. We hypothesize that the combination of multiple genes may generate biomarkers with prognostic potential. The current review attempts to group more than 161 different potential biomarkers involved in respiratory inflammation to pave the way for future classifiers. The potential biomarkers are categorized into either epithelial or infiltrate-derived or mixed origin, epithelial biomarkers. Furthermore, surface markers were grouped into cell-type-specific categories. The current literature provides multiple biomarkers for potential asthma endotypes that are related to T-cell phenotypes such as Th1, Th2, Th9, Th17, Th22 and Tregs and their lead cytokines. Eosinophilic and neutrophilic asthma endotypes are also classified by epithelium-derived CCL-26 and osteopontin, respectively. There are currently about 20 epithelium-derived biomarkers exclusively derived from epithelium, which are likely to innovate biomarker panels as they are easy to sample. This article systematically reviews and categorizes genes and collects current evidence that may promote these biomarkers to become part of allergic rhinitis or allergic asthma classifiers with high prognostic value.

Flow-assisted basophil activation tests in immediate drug hypersensitivity: two decades of Antwerp experience

The last two decades have witnessed that flow-assisted analysis of in vitro-activated basophils can constitute a valuable adjunct in the in vitro diagnostic approach of immediate drug hypersensitivity reactions (IDHR). This article summarises the current experience with the basophil activation test in the diagnosis of IDHR, with particular focus on allergy to curarising neuromuscular blocking agents, antibiotics (β-lactams and fluoroquinolones), iodinated radiocontrast media and opiates.

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.

The clinical utility of basophil activation testing in diagnosis and monitoring of allergic disease

The basophil activation test (BAT) has become a pervasive test for allergic response through the development of flow cytometry, discovery of activation markers such as CD63 and unique markers identifying basophil granulocytes. Basophil activation test measures basophil response to allergen cross-linking IgE on between 150 and 2000 basophil granulocytes in <0.1 ml fresh blood. Dichotomous activation is assessed as the fraction of reacting basophils. In addition to clinical history, skin prick test, and specific IgE determination, BAT can be a part of the diagnostic evaluation of patients with food-, insect venom-, and drug allergy and chronic urticaria. It may be helpful in determining the clinically relevant allergen. Basophil sensitivity may be used to monitor patients on allergen immunotherapy, anti-IgE treatment or in the natural resolution of allergy. Basophil activation test may use fewer resources and be more reproducible than challenge testing. As it is less stressful for the patient and avoids severe allergic reactions, BAT ought to precede challenge testing. An important next step is to standardize BAT and make it available in diagnostic laboratories. The nature of basophil activation as an ex vivo challenge makes it a multifaceted and promising tool for the allergist. In this EAACI task force position paper, we provide an overview of the practical and technical details as well as the clinical utility of BAT in diagnosis and management of allergic diseases.

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.

Carboplatin-induced severe hypersensitivity reaction: role of IgE-dependent basophil activation and FcεRI

Basophil activation was observed in patients with a history of carboplatin-induced severe hypersensitivity reaction (HR). However, the precise mechanism by which carboplatin induces basophil activation and the associated surrogate markers remains to be elucidated. To investigate whether IgE-dependent mechanisms, including the overexpression of FcεRI, participate in carboplatin-induced basophil activation, 13 ovarian cancer patients were enrolled: 5 with a history of carboplatin-induced severe hypersensitivity reaction within the past 2 years, and 8 with no such history. The expression levels of FcεRI, IgE, and CD203c on basophils were measured using a flow cytometer. Immunoglobulin E-dependent basophil activation was evaluated by testing for IgE passive sensitization using lactic acid, and by testing for phosphatidylinositol 3-kinase inhibition, using wortmannin. In three patients positive for carboplatin hypersensitivity, pretreatment with wortmannin almost completely inhibited carboplatin-induced basophil activation (P < 0.05). In a healthy control subject, whose own IgE showed no response to carboplatin, acquired reactivity to carboplatin when exposed to plasma from patients positive for carboplatin hypersensitivity. This did not occur when the same experiment was carried out using plasma from the patients negative for carboplatin hypersensitivity. Moreover, pretreatment with omalizumab, a monoclonal anti-IgE antibody, almost completely blocked carboplatin-induced basophil activation in the plasma of patients positive for carboplatin hypersensitivity. On further investigation, the HR-positive group had significantly higher levels of FcεRI compared with the negative group (P < 0.05). In conclusion, an IgE-dependent mechanism incorporating FcεRI overexpression participates in carboplatin-induced severe HR. These results establish the relevance of monitoring the pharmacodynamic changes of basophils to prevent carboplatin-induced severe HR.

Diagnosis and management of immediate hypersensitivity reactions to cephalosporins

Cephalosporins can cause a range of hypersensitivity reactions, including IgE-mediated, immediate reactions. Cephalosporin allergy has been reported with use of a specific cephalosporin, as a cross-reaction between different cephalosporins or as a cross-reaction to other β-lactam antibiotics. Unlike penicillins, the exact allergenic determinants of cephalosporins are less well understood and thus, standardized diagnostic skin testing is not available. Nevertheless, skin testing with diluted solutions of cephalosporins can be valuable in confirming IgE-mediated hypersensitivity reactions. In vitro tests are in development using recent technological advances and can be used as complementary tests. However, they are not commonly used because of their reduced sensitivity and limited availability. In selected cases of inconclusive results in both skin tests and IgE assays, a graded challenge or induction of drug tolerance with the implicated cephalosporin should be performed.