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Background: Evaluation of drug allergy is intricate because of nonstandardized testing and challenge method variability., Objective: To determine the clinical and epidemiologic characteristics of a large group of patients with suspected drug allergies who underwent 1 or more provocation tests (PT), and to establish whether performing this test in fewer steps is safe and effective., Methods: A cross-sectional descriptive study was conducted in patients with suspected drug allergies who underwent a provocation test at the allergy service of Fundación Valle del Lili, Cali, Colombia, from January 2011 to August 2017., Results: A total of 508 patients underwent 615 PTs; the median age was 34.5 years (range, 1-87 years) and 332 were women (65.3%). The most frequently implicated drugs were nonsteroidal anti-inflammatory drugs in 362 patients (58.9%), followed by beta-lactam antibiotics in 170 (27.6%), and non-beta-lactam antibiotics in 21 (3.4%). The most typically described manifestations were cutaneous urticaria in 282 patients (45.8%) and angioedema in 220 (35.7%). Most patients underwent the PT without performing other previous tests, which were done in only 92 patients (18.3%). Skin prick tests and intradermal reaction tests were performed in 81 patients (15%); all results were negative. In 519 patients (84.3%), the PT was performed in 2 steps without a placebo. Of the PTs performed in 2 steps, 492 (94.8%) had negative results. In addition, PT was performed in 195 patients (37.6%) in whom 2 equal doses of the drug was administered; 186 patients (95.4%) had negative results., Conclusion: Performing an open PT (without previous tests) in 2 steps among patients with low-risk drug reactions is safe. However, every case must be analyzed individually in terms of the risk-benefit ratio., (Copyright © 2020 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Immunogenicity assays are required to measure antidrug antibodies that are generated against biotherapeutic modalities. As for any ligand-binding assays, critical reagents (CR) play a crucial role in immunogenicity assays, as the robustness and reliability of an assay are defined by the quality and long-term availability of these reagents. The current regulatory guidelines do not provide clear directions on how to implement and verify lot-to-lot changes of CR during an assay life cycle, or the acceptance criteria that should be used when implementing new lots of CR. These aspects were extensively discussed within the European Bioanalysis Forum community. In this paper, CR for immunogenicity assays are identified and the minimum requirements for introducing new lots of CR in immunogenicity assays are described.

Purpose of Review: To present the most recent evidence on beta-lactam hypersensitivity reactions in children., Recent Findings: Drug provocation tests (DPTs) are the gold standard when investigating beta-lactam allergy in children and evidence is increasingly supporting DPTs without skin tests as a safe approach when evaluating children with nonimmediate mild reactions to beta-lactams. Of note, data are limited in the adolescent population, and this attitude may not apply to this age group. Standardization of DPT protocols is required in nonimmediate reactions, as many protocols ranging from 1 to 10 days have been described. The optimal duration of DPT is still unknown, with extended protocols providing slightly more sensitivity and possible higher long-term compliance, at the expense of potential side effects associated with prolonged antibiotic use. On the other hand, 1-day DPTs will identify the vast majority of patients, and the rest will only develop a mild rash during a subsequent full treatment. The natural history of beta-lactam allergy in children is not well studied with recent evidence pointing to the resolution of most confirmed beta-lactam allergies after 3 years., Summary: Further studies are needed for the standardization of DPT protocols and to confirm the favourable natural history of beta-lactam drug allergies in children. In addition, multicentric studies are required to confirm the increasingly accepted position of performing DPTs without skin tests in nonimmediate mild reactions to beta-lactams and to further evaluate the possibility of performing DPTs in benign immediate reactions to beta-lactams in children.

Purpose of Review: NSAIDs are the drugs most frequently involved in hypersensitivity reactions (HSR). These are frequently prescribed at all ages. HSR are of great concern and can affect people at any age. These drugs can induce reactions by stimulating the adaptive immune system (IgE or T cell), known as selective responders or more frequently by abnormalities in biochemical pathways related with prostaglandin metabolism. These are known as cross-intolerant. With some exceptions, skin testing and in-vitro studies are of little value in selective responders., Recent Findings: In the last years, several classifications have been provided based on clinical symptoms, time interval between drug intake and appearance of symptoms, response to other nonchemically related NSAIDs and the underlying disease. Based on this classification, several well differentiated categories within each group of entities cross-intolerant and selective responders are now recognized. The most complex groups for evaluation are cross-intolerant in which three major groups exist: NSAIDs exacerbated respiratory disease, NSAIDs exacerbated cutaneous disease and NSAIDs-induced urticaria/angioedema in the absence of chronic spontaneous urticaria. Within the selective responders, there are two mechanisms involved: drug-specific IgE or T-cell effector responses. New entities have been added to this classification like mixed reactions within the cross-intolerant category, that must manifest as anaphylaxis and multiple immediate selective reactions., Summary: The precise evaluation of patients with NSAIDs hypersensitivity following established guidelines will improve not only our understanding but also the management of these entities. As the number of patients affected with NSAIDs is important, further studies are warranted.

Background: The drug provocation test (DPT) is considered as the gold standard to diagnose drug allergy and is particularly important in the diagnosis of nonimmediate beta-lactam (BL) allergy in children. The natural history of BL allergy remains unknown., Objective: Our main aim was to evaluate the natural history of nonimmediate BL hypersensitivity and the long-term tolerance acquisition, and our secondary objective was to determine the negative predictive value (NPV) of the DPT following a 2-day protocol., Methods: Children developing a benign rash while treated by BL were prospectively recruited at the Emergency Department of the Geneva University Hospital from 2006 to 2011 and challenged with the incriminated BL (initial diagnostic drug provocation test [idDPT]) following a 2-day protocol. In case of a positive idDPT, the patients underwent a follow-up drug provocation test (fuDPT) 3 years later. In case of a negative idDPT, we sent a questionnaire to assess tolerance of a subsequent treatment with the incriminated BL., Results: Among the 18 children with a positive idDPT, 16 children (89%) had a negative fuDPT and 2 children developed a benign exanthema. Among those 16 children, 11 tolerated a subsequent treatment with the incriminated BL without any reaction, suggesting natural antibiotic tolerance acquisition. From another point of view, we found that the NPV of the DPT following a 2-day protocol was excellent at 96.7%., Conclusions: Our data strongly suggest that a fuDPT is safe and useful to assess tolerance acquisition in children with a confirmed benign nonimmediate BL allergy. In addition, our results support the use of a short DPT protocol (2 days), which led to a high NPV of 96.7% in our population, with a favorable benefit-risk balance., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Titanium is used in a wide variety of materials ranging from medical devices to materials used in everyday life. Adverse biological reactions that could occur in patients, consumers, and workers should be monitored and prevented. There is a lack of available agents to test and predict titanium-related hypersensitivity. The aim of this study was to develop two bioavailable titanium substances in ionic and nanoparticulate form to serve as antigens for hypersensitivity testing in vitro. Peripheral blood mononuclear cells from 20 test subjects were stimulated with the antigens and secretion of monocytic and lymphatic cytokines and chemokines were measured by a multiplex bead assay. Lymphocyte stimulation indices were also determined in a subset of test subjects by measuring CD69 and HLA-DR expression by flow cytometry. Cytokine profiling revealed that both antigens increased production of typical monocyte and macrophage secreted cytokines after 24 h, with significant increases in IL-1β, IL-7, IL-10, IL-12, IL-2R, IL-6, GM-CSF, TNF-α, IL-1RA, MIP-1α, MIP-1β, IFN-α, and IL-15. Lymphatic cytokines and chemokines were not significantly induced by activation. After seven days of stimulation, ionic-Ti (2.5 μg/mL) caused proliferation (stimulation index > 2) of CD4+ cells and CD8+ cells in all persons tested ( N = 6), while titanium dioxide nanoparticles (50 μg/mL) only caused significant proliferation of CD4+ cells. Our preliminary results show that the experimental titanium antigens, especially the ionic form, induce a general inflammatory response in vitro. A relevant cohort of test subjects is required to further elucidate their potential for predictive hypersensitivity testing., Competing Interests: The authors declare no conflict of interest.

Drug-induced liver injury (DILI) is a growing problem. Diagnostic methods to differentiate DILI caused by an adaptive immune response from liver injury of other causes or to identify the responsible drug in patients receiving multiple drugs, herbals and/or dietary supplements (polypharmacy) have not yet been established. The lymphocyte transformation test (LTT) has been proposed as a diagnostic method to determine if a subject with an apparent hypersensitivity reaction has become sensitized to a specific drug. In this test, peripheral blood mononuclear cells (PBMC) collected from a subject are incubated with drug(s) suspected of causing the reaction. Cell proliferation, measured by the incorporation of [ 3 H]-thymidine into new DNA, is considered evidence of a drug-specific immune response. The objectives of the current studies were to: (1) develop and optimize a modified version of the LTT (mLTT) and (2) investigate the feasibility of using the mLTT for diagnosing DILI associated with an adaptive immune response and identifying the responsible drug. PBMC collected from donors with a history of drug hypersensitivity reactions to specific drugs (manifested as skin rash) were used as positive controls for assay optimization. Following optimization, samples collected from 24 subjects enrolled in the U.S. Drug-Induced Liver Injury Network (DILIN) were tested in the mLTT. Using cytokine and granzyme B production as the primary endpoints to demonstrate lymphocyte sensitization to a specific drug, most samples from the DILIN subjects failed to respond. However, robust positive mLTT responses were observed for two of four samples from three DILIN subjects with hepatitis due to isoniazid (INH). We conclude that the mLTT, as performed here on frozen and thawed PBMC, is not a reliable test for diagnosing DILI caused by all drugs, but that it may be useful for confirming the role of the adaptive immune response in DILI ascribed to INH.

Suspected allergy to penicillins and cephalosporins is very common in childhood. After a proper evaluation, allergy will be confirmed only in a small portion of them. Intradermal tests are usually part of the allergy workup, but they are painful for children and time-consuming, and their role has been debated. A systematic review found only two studies reporting a positive predictive value of skin tests in children of 36% and 33%, respectively, leading to a high rate of inaccurate diagnosis. Moreover, considering that skin tests are negative in more than 90%-95% of cases, an oral provocation test (OPT) is finally needed to confirm tolerance in most of these children. Positive OPT are rare, and even where children demonstrate reproducible signs on challenge, they rarely constitute immediate or serious symptoms. Therefore, OPT to the index antibiotic without skin tests are increasingly being considered an accepted procedure for children with a suspected mild non-immediate reaction related to a beta-lactam antibiotic. Furthermore, a recent research has taken the same approach including children with suspected mild immediate reactions, with similar safety and positive results. In light of recent evidence highlighted, it is now the time for large and multicentric studies to confirm that OPT with the index antibiotic, without skin tests, are safe and convenient for children with a history of a mild reaction with a beta-lactam antibiotic before it can be recommended in pediatric allergy guidelines., (© 2017 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.)

Background: Penicillin allergy is commonly reported in the pediatric emergency department (ED). True penicillin allergy is rare, yet the diagnosis results from the denial of first-line antibiotics. We hypothesize that all children presenting to the pediatric ED with symptoms deemed to be low-risk for immunoglobulin E-mediated hypersensitivity will return negative results for true penicillin allergy., Methods: Parents of children aged 4 to 18 years old presenting to the pediatric ED with a history of parent-reported penicillin allergy completed an allergy questionnaire. A prespecified 100 children categorized as low-risk on the basis of reported symptoms completed penicillin allergy testing by using a standard 3-tier testing process. The percent of children with negative allergy testing results was calculated with a 95% confidence interval., Results: Five hundred ninety-seven parents completed the questionnaire describing their child's reported allergy symptoms. Three hundred two (51%) children had low-risk symptoms and were eligible for testing. Of those, 100 children were tested for penicillin allergy. The median (interquartile range) age at testing was 9 years (5-12). The median (interquartile range) age at allergy diagnosis was 1 year (9 months-3 years). Rash (97 [97%]) and itching (63 [63%]) were the most commonly reported allergy symptoms. Overall, 100 children (100%; 95% confidence interval 96.4%-100%) were found to have negative results for penicillin allergy and had their labeled penicillin allergy removed from their medical record., Conclusions: All children categorized as low-risk by our penicillin allergy questionnaire were found to have negative results for true penicillin allergy. The utilization of this questionnaire in the pediatric ED may facilitate increased use of first-line penicillin antibiotics., Competing Interests: POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2017 by the American Academy of Pediatrics.)

Unlabelled: Drug allergy is the third most common reason for allergy consultations. There is a tendency to call any adverse drug reaction (ADR) allergic, even without confirmatory allergy study., Objectives: (1) Evaluate time of resolution allergy to beta-lactam's study in a sample of 100 patients. (2) Analyse cost-effectiveness of current diagnostic study (skin tests, specific IgE and drug provocation test (DPT)). (3) Describe type and frequency of ADRs in adult/paediatric patients. (4) Compare cost of complete study with DPT. (5) Assess the need to restructure current study methodology according to results obtained. The study is part of a strategic plan of the allergy department (2005-2010). Patients with suspected allergy to beta-lactams were included. Procedures performed: medical history, specific IgE, skin tests and DPT. Cost/patient analysis. Cost of protocol analysis for current diagnostic/direct DPT., Results: 100 patients were studied, 52 females/48 males; 43 children/57 adults., Symptoms: 89 cutaneous, 4 anaphylaxis, 3 vasovagal reactions, 6 non-specific symptoms and 4 not recalled. Allergy was confirmed in six patients (only one child). Complete-study cost: 149.3 Euros/patient. DPT-study cost: 97.19 Euros/patient (34.9% less). Resolution time 9-13 months, absenteeism 28.04%., Conclusions: In the series studied, diagnosis of allergy to beta-lactams was confirmed in 6% of patients (2.3% of paediatric patients). After analysing results and cost of the study we believe that we should propose a specific diagnostic algorithm in those paediatric patients without suspected IgE-mediated ADR, and for those patients direct DPT should be conducted. This will reduce cost/patient (-34.9%), time of resolution and absenteeism., (Copyright © 2014 SEICAP. Published by Elsevier Espana. All rights reserved.)

In the face of increasing prevalence of hypersensitivity reactions, introduction of effective, reliable and safe methods plays a crucial role in their diagnosing. Among the currently available laboratory (in vitro) methods is basophil activation test (BAT). It is a flow- cytometry based assay that allows to identificate in the blood sample basophils and additionally to asses the degree of cell activation after exposure to an antigen. The most common superficial identification markers are CD63 and CD203c, which increase in number after activation. Basophil actvation test can be applied to confirm diagnosis of allergy to Hymenoptera venoms, food, pollens and hypersensitivity to drugs. The aim of present paper is to present theoretical methods of this test as well as its pros and cons. We focus also on presentation of clinical case where BAT seemed to be a necessary addition to a routine diagnostic pathway. We present a case of identification of the culprit drug which caused an anaphylactic reaction.

Multiple drug hypersensitivity (MDH) is an allergy to two or more chemically unrelated drugs. We present a case of MDH caused by antituberculosis agents during the treatment of tuberculous meningitis (TBM). A 64-year-old man without a history of drug allergy developed fever and severe headache. Examination of cerebrospinal fluid showed lymphocytosis, a low glucose level, and a high ADA activity, suggestive of TBM. The patient was treated with isoniazid, rifampicin, pyrazinamide, and ethambutol, and his symptoms resolved quickly. However, 20 days after the initiation of therapy, he developed remittent fever without mucocutaneous lesions. A drug-induced lymphocyte stimulation test was positive for isoniazid, rifampicin, and pyrazinamide, which was consistent with a diagnosis of MDH. All the antituberculosis drugs were replaced with levofloxacin and ethionamide, both of which have excellent cerebrospinal fluid penetration, and the fever subsided. The patient made a full recovery from TBM. Because standard antituberculosis regimens include three or four antituberculosis drugs, it is difficult to determine the culprit drug when hypersensitivity occurs. Moreover, there can be multiple causative drugs as illustrated by the present case. During a time-consuming desensitization therapy, TBM could flare up, leading to permanent neurological damage. Thus, treatment with suitable alternative drugs should be started immediately.

Background: Graded challenges are the criterion standard for evaluating adverse drug reactions (ADR). Evidence-based guidelines regarding the optimal number of steps for challenges are lacking., Objective: To determine the safety and outcomes of 1- or 2-step test doses among patients with ADRs seen by the allergy/immunology consult service and to compare the outcomes of 1- or 2-step test doses with multistep challenges performed during the same time period., Methods: We conducted a retrospective chart review of all 1- or 2-step test doses and multistep challenges at a single academic center between 2008 and 2013. Patient demographics, symptoms of initial ADRs, and outcomes of test doses and multistep challenges were reviewed. ADRs were classified by type and were graded by severity. Outcomes of 1- or 2-step test doses were compared with multistep challenges., Results: We identified 456 patients who underwent 497 one- or 2-step test doses (mean age, 51 years; 67.5% female patients). The most common drugs that prompted test doses were β-lactams (62%). The majority of patients (n = 444 [89%]) did not experience any ADRs during test doses. ADRs that occurred during test doses (n = 53 [11%]) were most commonly non-immune-mediated (45%) or IgE-mediated (32%), with grade 1 or 2 severity (100%). Forty-nine percent of ADRs during test doses did not receive any treatment. The ADR rate during multistep challenges (10/82 [12%]) was similar to test doses., Conclusion: One- or 2-step test doses were safe for evaluation of ADRs. Multistep challenges did not confer added safety. Furthermore, 1- or 2-step test doses did not raise concern for induction of tolerance., (Published by Elsevier Inc.)

Non-immediate drug reactions (NIR) are induced by specific immunological mechanisms and involve the recognition of hapten molecules by the immune system, with the participation of dendritic cells and other antigen-presenting cells. This process is followed by an effector response that can induce several clinical entities, ranging from mild to severe. The type of immunological recognition can be used as the basis for the diagnostic approach. Both in vivo and in vitro tests are available for the diagnosis of NIR. In vivo tests consist of the reproduction of a diminished immune response with the culprit drug and in vitro tests are based on the stimulation of memory cells in culture. If both tests give negative results, a drug provocation test can be used.

NSAIDs are the most commonly used medications worldwide and are responsible for almost 25% of adverse drug reactions. Such reactions can have different manifestations and can be immunologic or non-immunologic. The diagnosis is primarily based on the medical history, which can be difficult in patients receiving multiple medications. Because skin testing and blood tests are not valid for NSAIDs reactions, confirmation requires an appropriately-designed challenge. The latter could be avoided when the history is obvious and the reaction is life-threatening. The challenge route can be oral, nasal, or bronchial. Avoidance of the causative NSAID, often associated with the avoidance of the cross-reacting preparations, is the cornerstone of management. In most cases, a safe substitute can be used. When treatment with the causative NSAID is necessary, titrated desensitization can be performed. This review discusses the classes of NSAIDs, mechanisms of their adverse reactions, manifestations, diagnosis, and management.

A 62-year-old man with refractory leukemia transformed from myelodysplastic syndrome was placed on hydroxyurea (hydroxycarbamide) at a daily dose of 500 mg. Because of insufficient cytoreductive efficacy, the dose was increased to 1,500 mg five days later. Eight days after the initiation of hydroxyurea, the patient started complaining of chills, fever, and vomiting. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were markedly elevated to 5,098 and 3,880 IU/l from 44 and 59 IU/l in one day, respectively. Tests for hepatitis viruses were all negative. With the discontinuation of hydroxyurea, AST and ALT returned to their former levels within two weeks. A drug-induced lymphocyte stimulation test for hydroxyurea was positive with a stimulating index of 2.0. Hepatic dysfunction has been recognized as one of the side effects of hydroxyurea. However, there have been only a limited number of reports demonstrating drug allergy to have a role in hepatic dysfunction accompanied by fever and gastrointestinal symptoms. The findings of our case strongly suggest that all presentations could be explained by drug allergy. Physicians should be mindful of the potential for acute and severe hepatic dysfunction due to allergic reaction against hydroxyurea.

Background: Drug provocation tests (DPTs) need technical equipment, staff and time. There are very few allergy centres performing DPTs in Turkey. Therefore many patients are referred to these centres. One day triple-double antibiotic or non-steroidal anti-inflammatory drug (NSAID) oral DPT for determining safe alternatives is safe, cost-effective and time saving compared to conventional one day one drug oral DPT. Our aim was to investigate the safety of antibiotic-NSAID oral DPT performed on the same day to find safe alternatives in multidrug hypersensitive patients., Methods: Forty-two patients who had been diagnosed as having both antibiotic and NSAID hypersensitivity were enrolled to the study between 15 November and 15 July 2010. The reactions were urticaria and/or angio-oedema not including laryngeal oedema for all patients. Two antibiotics-one NSAID or two NSAIDs-one antibiotic triple test have been performed on the same day to study patients (n=22), while the control group (n=20) had taken drugs on three separate days., Results: Only two patients had positive reactions during triple test and two patients had adverse reactions; one had gastric pain, one had nausea. Three patients in the control group had positive reactions. There were no significant differences between the two groups in frequency of adverse and allergic drug reactions (p>0.05). Sixty days were spent for the tests of the control group with only 28 days for the study population., Conclusion: Triple test performed with antibiotic and NSAID on the same day for determining safe alternatives for multidrug hypersensitive patients reporting non-life-threatening allergic reactions seems to be safe and time-saving., (Copyright © 2011 SEICAP. Published by Elsevier Espana. All rights reserved.)

Purpose of Review: In the last years, many novel drugs have been introduced, generating new patterns of drug hypersensitivity. There are also novel clinical and biologic techniques that have enabled us to understand the mechanisms and diagnosis of reactions to old used drugs. This review summarizes current knowledge on the epidemiology, mechanisms, and clinical and in-vitro diagnosis of these reactions., Recent Findings: Traditional and complementary alternate medicines are also causes of adverse drug reactions, and many of them are cataloged as allergy. Research in the field of skin and drug provocation test to antibiotics such as beta-lactams and carbapenems, and iodinated and gadolinium contrast media has allowed the understanding of cross-reactivity reactions and permitted the use of well tolerated alternate drugs in cases of proper negative drug allergy work-up. Many unique cases have been reported, including diverse drugs as infliximab, succinylcholine, hydroxychloroquine, that widen the spectrum of clinical manifestations of drug hypersensitivity to various drugs. Several studies have been published in the field of in-vitro diagnosis, including basophil activation tests, radioallergosorbent test, Immuno-Cap, ELISA, enzyme-linked immunospot assays, and T-cell proliferation tests allowing novel approaches to assess drug allergy., Summary: As new and old drugs continue to be used, new reports regarding new and known drug hypersensitivity manifestations are made. Advances in mechanisms are enhanced by the use of new in-vitro techniques to detect specific antibodies or T cells. Research in the field of skin and provocation tests has allowed the use of well tolerated alternate drugs in individuals with proven drug allergy.

The histopathological examination of lymphoid organs together with a T-dependent antibody (TDAR) assay are the primary components of preclinical immunotoxicity assessment. Additional testing including measurement of cellular immunity may be considered. Besides ex vivo lymphocyte proliferation assays, either delayed or contact hypersensitivity models can be used. Contact hypersensitivity testing is typically performed either in mice or in guinea pigs and is directly derived from classical models used for the detection of contact sensitizing chemicals. Whatever the selected model, it is comprised of a sensitizing phase where the animals are applied a strong contact sensitizer topically, then a rest phase, and finally an eliciting phase where sensitized animals are challenged topically with the same contact sensitizer.In mice, the ear-swelling test is the reference procedure in which mice are sensitized to the ear or shaved abdominal skin and then challenged on the ear. Ear swelling usually measured from ear thickness reflects a cell-mediated immune response. In guinea pigs, a strong sensitizer is applied on the shaved skin of the abdomen or the interscapular area. The sensitized animals are challenged on another area of the shaved abdomen, and the cell-mediated response is assessed semiquantitatively from the magnitude of induced erythema inconsistently associated with edema. Treatment or exposure with immunosuppressive chemicals can result in a significantly decreased ear swelling or skin reaction. Contact hypersensitivity models are seldom used nowadays in preclinical immunotoxicity testing, most likely because of the lack of standardization and extensive validation as well as their use being restricted to mice or guinea pigs.

Drug provocation tests in children are always a problematic task. In the present article the most important aspects of this technique are reviewed, including the differences between children and adults; the main mechanisms involved in drug reaction; how to perform the different tests; and when they are indicated.

Provocation tests are regarded as the "gold standard" to establish or exclude the presence of hypersensitivity to a certain drugs because they reproduce not only allergy symptoms but other adverse manifestations, irrespective of their pathomechanism. Provocation testing is potentially harmful and should be considered only after balancing the risk-benefit ratio in the individual patient. The reasons for false-positive and false-negative results are numerous, including loss of sensitization, cofactors not being included in the diagnostic procedure, and the potential induction of tolerance during provocation. When conducted by experienced clinicians in a carefully monitored setting, however, drug provocation testing is a safe method to confirm or exclude drug hypersensitivity.

Background: To confirm allergy to beta-lactam (BL), a basophil activation test in flow cytometry based on CD63 up-regulation was described. CD203c is a more recent basophil activation marker and up to day there is no consensus about which marker is the more sensitive one. CD203c has not yet been evaluated in the diagnosis of BL allergy., Objective: The aim of the study was to compare the reliability of CD203c to CD63 for the diagnosis of amoxicillin (AX) allergy, which is nowadays the most frequent BL allergy., Methods: Twenty-seven patients with an immediate positive skin test (ST) to AX, 20 had had anaphylaxis with AX and 7 had urticaria and/or angioedema, were compared with 14 controls with no allergy to BL and to six patients with delayed positive ST to AX., Results: In the anaphylaxis group, AX induced up-regulation of CD203c in the basophils of 12 patients out of 20 (60%) and of CD63 in four patients (20%) (P<0.02). Two patients out of seven with urticaria or angioedema had a positive result with CD203c and CD63. In patients who had anaphylaxis, ampicillin (AMP) induced CD203c up-regulation in eight out of 12 (67%) patients tested, and CD63 up-regulation in 4 out of 12 (33%) (all patients who had anaphylaxis could not be tested with AMP). False-positive results were observed with CD203c as well as CD63, and for 10 patients indeed this was confirmed by a negative drug provocation test. The origin of conflicting results between CD63 and CD203c might be at least the targeting of basophils based on anti-IgE labelling. Among IgE(+) gated cells, by means of CD33, a marker of monocytes, a contamination up to 50% by monocytes was detected. In contrast to CD63, CD203c is an activation marker specific of basophils with a basal low-level expression in resting basophils. Thus, IgE and CD203c double targeting of basophils avoids the contamination by monocytes., Conclusion: CD203c seems to be a more sensitive activation marker of basophils than CD63 for the diagnosis of amoxicillin allergy.

Purpose of Review: Nonimmediate reactions to beta-lactams include several clinical entities, from maculopapular rash to severe reactions such as Steven-Johnson syndrome. Toxic epidermal necrolysis and organ-specific reactions may also occur., Recent Findings: Progress has been made in understanding the role of the immunological system in nonimmediate reactions to beta-lactams. Different T-cell subsets recognize beta-lactams after haptenation of serum or cell proteins in the context of major histocompatibility complex. Studies using T-cell lines and clones have shown that a heterogeneous response is generated, with the expression of different cytokine profiles. Betalactams also act on dendritic cells, inducing changes that enable them to interact with naïve lymphocytes, becoming memory T cells. Tissue-activated CD4 and CD8 cells express perforin and other cytotoxic mediators that elicit the lesions. Studies on the clinical course of these entities indicate that cells migrate, establishing a recirculation with homing to the skin and back to the circulation. These cells thus participate not only in skin lesions but probably also in the repair process., Summary: Understanding the immunological mechanisms involved in nonimmediate reactions to beta-lactams has improved over the last few years, with better definition of the different T-cell subpopulations involved. Experimental studies and monitoring of the response support the implication of different cell subsets.

Purpose of Review: The present review addresses the most recent literature regarding the diagnosis of drug hypersensitivity reactions, which can be classified as immediate or nonimmediate according to the time interval between the last drug administration and the onset. Immediate reactions occur within 1 h; nonimmediate ones occur after more than 1 h., Recent Findings: Clinical and immunological studies suggest that type-I (IgE-mediated) and type-IV (cell-mediated) pathogenic mechanisms are involved in most immediate and nonimmediate reactions, respectively. New diagnostic tools, such as the basophil activation test and the lymphocyte activation test, have been developed and are under validation., Summary: In diagnosis, the patient's history is fundamental; the allergologic examination includes in-vivo and in-vitro tests selected on the basis of the clinical features. Prick, patch, and intradermal tests are the most readily available forms of allergy testing. Determination of specific IgE levels is still the most common in-vitro method for diagnosing immediate reactions. The sensitivity of allergologic tests is not 100%; in selected cases, therefore, provocation tests are necessary. The routine use of the basophil activation test and the lymphocyte activation test could increase the sensitivity of diagnostic work-ups, thus reducing the need for drug provocation tests.

Background: Phenytoin can induce diversified adverse reactions including generalized eruptions and the hypersensitivity syndrome. Delayed-type allergic mechanisms have been postulated to underlie these reactions. The tests most widely used to detect T-cell sensitization to drugs are the patch test and the lymphocyte transformation test (LTT), but their sensitivity is not sufficient. Simultaneous assessment of both the frequencies and the cytokine-producing phenotypes of allergen-specific T cells has become possible with the recently introduced carboxyfluorescein succinimidyl ester (CFSE) assay., Methods: Seven patients who presented with phenytoin-induced maculopapular exanthema with and without fever were included in this study. Peripheral blood mononuclear cells (PBMCs) were labeled with CFSE and cultured with phenytoin for seven days. The cells were stained with anti-CD4 and cytokine-specific monoclonal antibodies (MoAbs), and analyzed with FACSCalibur., Results: The phenytoin-specific proliferation of CD4+ cells in patients was significantly higher than in the four controls exposed to phenytoin, and in seven healthy children with no previous phenytoin intake. A significant difference in the percentages of CD4+ IFN-gamma+ cells between patients and the seven healthy children was observed. The sensitivity and specificity of proliferation were 100% and 90.9%, and those of IFN-gamma secretion were 71.4% and 100%, respectively., Conclusions: Phenytoin-specific proliferation may be detected with greater sensitivity by the CFSE dilution assay than the conventional LTT. The assay revealed that both CD4+ and CD4- T cells proliferated and produced IFN-gamma and TNF-alpha after stimulation with phenytoin. The CFSE dilution assay might be useful for the diagnosis and understanding of drug hypersensitivity.

Diagnosis of drug-induced pneumonia, which represents pulmonary toxicity caused by certain drugs, is difficult, as a large number of different drugs can elicit various immune-mediated diseases with distinct pathomechanisms. The drug-induced lymphocyte stimulation test (DLST) is widely used for diagnosing drug-induced pneumonia in Japan. Recent reports, however, indicate that DLST is not reliable for diagnosis of drug-induced pneumonia. To diagnose drug-induced pneumonia, a provocation test with the suspected drug is the most reliable method of assessing the relationship between the drug and pneumonia. We examined the correlation between the DLST and the provocation test in 6 cases of suspected drug-induced pneumonia. DLST was performed in all of the patients. The causes of pneumonia in all patients were confirmed by a provocation test. The DLST was positive in 3 of 6 cases of suspected drug-induced pneumonia, but the suspected drugs were ruled out by the provocation test. If we had relied solely on the DLST, these 3 cases would have been labeled as false allergy. The results of the DLST did not coincide with the results of the provocation test in any of the cases. Our results suggest that the DLST is not useful for the diagnosis of drug-induced pneumonia. Following provocation with the causative drug, reappearance of pulmonary infiltration was not observed in any of the cases. These findings indicate that a carefully performed provocation test is the safe and most reliable method.

Most drug reactions are pharmacological reactions rather than hypersensitivity reactions. In assessing drug reactions, a detailed clinical history and careful documentation of reactions are most important. Elucidating the nature and time course (first versus subsequent exposure, immediate versus non-immediate) of a reaction can help to distinguish immune from non-immune hypersensitivity, as well as IgE-mediated from T cell-mediated allergy. Skin testing and in-vitro tests are of predictive value for only a limited group of IgE-mediated drug allergic reactions. Drug provocation challenges can be used to eliminate suspicion of a low-probability drug reaction, find a safe alternative to a proven or probable drug reaction, or as a means of desensitisation. If a patient taking an angiotensin-converting enzyme (ACE) inhibitor develops angioedema, the cause must be assumed to be the ACE inhibitor until proven otherwise.

Hypersensitivity reaction is an unexpected drug adverse effect which sometimes can lead to fatal condition. Confirmation of the suspected drugs that cause hypersensitivity reaction is sometimes difficult. Drug provocation test is still a gold standard to establish the diagnosis of hypersensitivity to certain drugs or agents. Drug provocation test is a controlled drug treatment which aims at making diagnosis of hypersensitivity reaction to drugs. We reported a demonstration case of a 47 year-old female patient with hypersensitivity to anti tuberculosis drugs (isoniazid, rifampicin, pyrazinamid and ethambutol). Drug provocation test is important in this case to confirm which drug had caused hypersensitivity reaction because anti tuberculosis drugs were the treatment of choice for her illness.

Drug-induced allergic adverse events including rash, interstitial pneumonia and hepatic injury are often observed in a few patients treated with anticancer drugs that are 5-FU derivatives, including TS-1. In patients suspected to be liable to develop allergic reactions, the drug-induced lymphocyte stimulation test (DLST), based on the (3)H-thymidine incorporation ratio into the DNA of lymphocytes derived from the patients, is generally employed to identify drugs that could induce allergy. In this case report, we conducted the DLST on 20 healthy volunteers without TS-1 treatment in order to obtain reference data on the evaluation of TS-1-induced allergy. Even though all 20 volunteers were healthy, there were 6 positive responses to the DLST. In view of the positive response to TS-1 in healthy volunteers undergoing the DLST, it is suggested that the DLST could show a false positive response through an intracellular function that accelerates incorporation of thymidine in the lymphocytes by the salvage pathway after inhibition of DNA de novo synthesis caused by 5-FU derivative anticancer, including TS-1. Therefore, such a positive response to the drugs is considered, in fact, to be false-positive in the DLST. In view of the occurrence of false-positive results, the possibility of drug-induced allergy in patients receiving TS-1 should be carefully evaluated using a combination of other clinical examinations.

Proper diagnosis of adverse drug reactions, although often complicated and difficult, is important for the patient and the physician. Often the question of whether it is safe to readminister a medication is an important clinical judgment that needs to be made. Alternative medications may be less effective or have greater toxicities or cost, or both. Areas of ongoing research to improve diagnostic precision for allergic drug reactions include further understanding of the immunochemistry of allergenic medications, improvement of the reproducibility and sensitivity of relevant in vitro assays, and further validation of computer-assisted evaluation of adverse drug events. The positive and negative predictive values for these diagnostic tests need to be better defined whenever possible. At present, the primary diagnostic tool for properly assessing immunologic drug reactions remains a meticulous and detailed history obtained by an astute, knowledgeable, and motivated physician.

Background: We assessed whether nonsteroidal anti-inflammatory drugs (NSAIDs) may provoke blood basophil activation in vitro in aspirin- and NSAID-hypersensitive patients, as detected by a flowcytometric technique using the CD63 marker--flowcytometric basophil activation test (FAST) assay--in addition to the sulfidoleukotriene (sLT) release--the cellular allergen stimulation test (CAST)., Methods: Sixty aspirin- and/or NSAID-hypersensitive patients were studied. Thirty control patients without history and negative provocation challenge were also included. The percentage of activated basophils after in vitro stimulation with NSAIDs at 3 different concentrations was evaluated by an anti-CD63 phycoerythrin conjugate (FAST assay) and the amount of sLTs released in the cell supernatant by ELISA (CAST assay)., Results: For aspirin, the FAST indicated a sensitivity of 41.7%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.4%; for paracetamol 11.7 and 100%, for metamizol 15 and 100%, for diclofenac 43.3 and 93.3%, and for naproxen 54.8 and 74.1%. Many patients showed positive tests to more than 1 NSAID. When considering the first 4 NSAIDs, the global sensitivity increased to 66.7%, while the specificity remained at 93.3%. The addition of the CAST results still increased the sensitivity up to 73.3%, but with a decrease of the specificity to 71.4%., Conclusions: The FAST shows a high percentage of positive reactions, which may reach 60-70% when 4 NSAIDs are tested and even 88% when the test is performed within 1 month of the last clinical drug exposure and reaction. The test has a high specificity above 90%. The addition of sLT determinations yields additional information in a few isolated cases. It is suggested that this test, when properly used, may help avoid some cumbersome and dangerous provocation challenges.

Background: Intolerance to acetylsalicylic acid (ASA) and other nonsteroidal anti-inflammatory drugs (NSAIDs) is a crucial problem in clinical practice. There is, therefore, a need for safer NSAIDs in patients with analgesic intolerance., Objective: To assess the safety of nimesulide, meloxicam, and rofecoxib, selective COX-2 inhibitors, in a group of ASA/NSAIDs-intolerant patients., Method: Tolerances to nimesulide, meloxicam, and rofecoxib were assessed by single-blind placebo-controlled oral challenges. One hundred twenty-seven subjects with history of adverse reaction to ASA/NSAIDs received oral challenges with nimesulide, 61 subjects were challenged with meloxicam, 51 subjects were challenged with rofecoxib, and 37 subjects were challenged with all three drugs. Placebos were given to all patients on the first day of the study. On the second day, one-fourth and three-fourths of the therapeutic doses of the active drugs (nimesulide 100 mg, meloxicam 7.5 mg, or rofecoxib 25 mg) were given at 60-minute intervals. There was at least a 3-day interval between challenge tests. Erythema, pruritus accompanied by erythema, urticaria/angioedema, rhinorrhea, nasal obstruction, sneezing, dyspnea, or cough associated with a decrease of at least 20% in the forced expiratory volume (FEV1) and hypotension were considered as positive reactions., Results: Positive reactions to the nimesulide, meloxicam, and rofecoxib challenges were observed in 18/127 (14.3%), 5/61 (8.1%), and 1/51 (2.0%) patients, respectively. In each group of nine patients, there were two patients with asthma and four who developed skin type reactions and asthmatic reactions, respectively, to the nimesulide challenge. Among five patients who reacted to the meloxicam challenge, asthmatic type reactions were detected in two asthmatics. Only one urticarial type reaction was observed with rofecoxib challenge in one patient who presented with anaphylaxis to ASA/NSAIDs. All patients with asthma tolerated rofecoxib without any adverse effects. None of the patients reacted to the placebo. Among 37 patients challenged with all three drugs, 11 reacted to nimesulide, and one patient reacted only to meloxicam. Three patients reacted to more than one of the drugs tested, and one of them reacted to all drugs., Conclusion: This is the first placebo-controlled report comparing these three drugs. The results indicate that among these alternative drugs for ASA/NSAIDs-intolerant patients, rofecoxib seems to have the most favorable tolerability.

Background: We assessed the reliability of basophil activation test (FAST) and sulphidoleukotriene production (CAST) in the in vitro diagnosis of allergy to metamizol, evaluating its sensitivity and specificity., Methods: Twenty-six patients allergic to metamizol and 30 control individuals were studied. Skin tests with metamizol, FAST, and CAST were performed., Results: FAST sensitivity was 42.3% and specificity 100%. The PPV of FAST is 100% and the NPV 99.4%. The likelihood ratio for a positive value cannot be calculated because the specificity is 100% and the likelihood ratio for a negative value is 0.58. CAST sensitivity was 52%, and specificity 90%. The PPV of the test is 5% and the NPV 99.5%. The likelihood ratio for a positive result was 5.2 and that for a negative result 0.53. FAST detects a larger number of cases when patients are studied within the first 6 months after the clinical reaction (chi = 4.2, P = 0.04) than later. Together with skin tests, FAST allowed detection of 69.2% patients allergic to metamizol, the same as CAST 76%. The joint use of the three techniques allowed identification of 76.9% of cases., Conclusions: FAST and CAST are useful for the diagnosis of allergy to pyrazolones. Its usefulness clearly increases when recent reactions are studied.

The diagnosis of immunologic drug reactions is based primarily on a detailed clinical history and historical data on relative immunogenicity of the culprit drugs. Except for a few standardized skin tests, most of the other methods for diagnosing drug allergy have unproven diagnostic or predictive clinical utility. Many tests for drug-specific immune responses are suggestive if positive, but have unknown negative predictive values. The present review addresses the most recent published literature regarding the diagnosis of drug allergy. Recent advances in the use of the lymphocyte transformation test, and delayed intradermal skin tests and patch tests for the diagnosis of delayed cutaneous reactions to penicillins suggest that these tests may have clinical utility, although confirmatory reports are still missing. For the diagnosis of acute vaccine reactions, gelatin-specific IgE as measured by radioallergosorbent test has now been shown to be reliably associated with allergic reactions to gelatin-containing vaccines.

There is a great need to develop a method for making an accurate and reliable in vitro diagnosis of adverse hypersensitivity reactions to drugs. We measured the amount of sulfidoleukotriene (sLT) released from the peripheral blood leukocytes obtained from 25 patients who developed hypersensitivity reactions following the administration of nonsteroidal anti-inflammatory drugs (NSAIDs); 12 patients demonstrated reactions to Voltaren, 8 patients to Bufferin, and 5 patients to Sedes G. The stimulation index, the ratio of the amounts of sLT (pg/ml) incubated with and without drugs, was considerably higher in the patients than in the controls, which consisted of 5 nonallergic healthy subjects. The sensitivity of the CAST (cellular antigen stimulation test) was evaluated to range from 62.5 to 80%, while the specificity was 70-100%. The CAST may thus be useful as a novel in vitro test system in order to screen for possible hypersensitive reactions to NSAIDs with both reliability and safety.

Preliminary literature reports suggest the possibility that, in an allergic patient, a previously positive allergological test may turn negative after a long period of time with no further exposure to the specific allergen. The aim of this study was to evaluate the rate by which a previously positive skin test or RAST may turn negative in a group of patients allergic to penicillin if no further exposure to the specific allergen occurs. Sixty-three patients allergic to penicillin (48 with type I allergy and 15 with type IV allergy) were enrolled in a long-term, prospective, follow-up study, undergoing a successive complete allergological testing within 6 years of the first positive examination. During the follow-up period, skin tests progressively became negative in 28 (58.3%) type I allergic patients and in only one (6.7%) subject with type IV allergy. Similarly, the positive RAST turned negative in as many as 13 subjects (43.3% of cases). The cumulative skin test positivity (type I allergy) was significantly lower than that of patch tests (type IV allergy) (chi 2 = 10.4; d.f. = 1; p < 0.005, Logrank test). No significant difference in the progressive rate of decrease in skin test and RAST cumulative positivity was observed in the 30 patients showing both RAST and skin test positivity on entering the follow-up study. Our results provide strong evidence that a positive allergological test performed in a drug-allergic patient may become negative with time, in the absence of further exposure to the specific antigen. A negative allergological test cannot, therefore, rule out the immunological basis of a drug sensitivity. This is why we always suggest advising patients with a personal history of drug hypersensitivity against any further administration of the responsible drug, even in the presence of a completely negative allergological examination.

The authors analyze published data on various modifications of the specific leukocyte lysis test (SLLT) and their own findings on in vitro osmotic leukocytolysis caused by low-molecular nonelectrolytes (urea, glycerol, and glucose), and present the estimation of osmotic pressure of these agents' solutions in equimolar concentrations. In contrast to the specific effect of allergens, an osmotic component of nonspecific leukocyte lysis is considered. A universal approach to the choice of working doses of drug in SLLT is proposed: equimolar solutions of the allergens (chemical and medicinal compounds). The necessity of further theoretical and practical research of SLLT is validated.

Oral leukocyte alteration method was established for the diagnosis of drug allergy. This method is 68% positive in patients with drug allergy and 7% positive in healthy persons. The whole procedure is simple and takes only an hour and a half.