Means of increasing sensitivity of an in vitro diagnostic test for aspirin intolerance

What happens to basophils and tryptase, LXA4 and CysLTs during aspirin desensitization?

INTRODUCTION

Aspirin desensitization (AD) is an effective treatment in patients with non-steroidal anti-inflammatory drugs (NSAID)-exacerbated respiratory disease (NERD) by providing inhibitory effect on symptoms and polyp recurrence. However, limited data is available on how AD works. We aimed to study comprehensively the mechanisms underlying AD by examining basophil activation (CD203c upregulation), mediator-releases of tryptase, CysLT, and LXA₄, and LTB₄ receptor expression for the first 3 months of AD.

METHODS

The study was conducted in patients with NERD who underwent AD (group 1: n = 23), patients with NERD who received no desensitization (group 2: n = 22), and healthy volunteers (group 3, n = 13). All participants provided blood samples for flow cytometry studies (CD203c and LTB₄ receptor), and mediator releases (CysLT, LXA_4, and tryptase) for the relevant time points determined.

RESULTS

All baseline parameters of CD203c and LTB₄ receptor expressions, tryptase, CysLT, and LXA₄ releases were similar in each group (p > 0.05). In group 1, CD203c started to be upregulated at the time of reactions during AD, and continued to be high for 3 months when compared to controls. All other study parameters were comparable with baseline and at the other time points in each group (p > 0.05).

CONCLUSION

Although basophils are active during the first 3 months of AD, no releases of CysLT, tryptase or LXA₄ exist. Therefore, our results suggest that despite active basophils, inhibition of mediators can at least partly explain underlying the mechanism in the first three months of AD.

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

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

Hypersensitivity to Aspirin and other NSAIDs: Diagnostic Approach in Patients with Chronic Rhinosinusitis

Hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs) associated with chronic rhinosinusitis (CRS) and/or asthma comprises a distinct clinical syndrome referred to as NSAIDs exacerbated respiratory disease (NERD). Patients with NERD tend to have more severe course of both upper (CRS and nasal polyps) and lower airway (asthma) diseases and are usually recalcitrant to conventional treatment modalities. Diagnosing and phenotyping of patients with NERD are critical for prevention of drug-induced adverse reactions and open novel options for management of underlying chronic airway inflammatory diseases. Diagnosis of NERD is based on detailed clinical history confirmed by challenge with aspirin, but new diagnostic approaches are currently being developed. This review article focuses on the diagnostic approach to a patient with CRS and hypersensitivity to NSAIDs, emphasizing the importance of diagnosis for proper patient's management.

Cellular in vitro diagnosis of adverse drug reactions

Adverse drug reactions can manifest clinically in a variety of ways. Whilst the majority can be explained by dose-dependent side effects, there is group of unpredictable immunological or non-immunological intolerances that represent a particular diagnostic challenge. Skin tests are frequently negative, whilst challenge tests are time-consuming and often hazardous. Against this backdrop, cellular in vitro tests play a particularly important role in the identification of the causative drug. Whilst basophil tests can be used in the case of immunoglobulin E (IgE)- as well as non-IgE-mediated hypersensitivity reactions, T-cellular test methods assist in the diagnosis of drug eruptions. The reliability of individual tests can be affected by a variety of parameters, such as the pathomechanism underlying the drug reaction, the causative medication, or the point in time of testing. Not only is a sound knowledge of the basic principles of the individual assays an essential prerequisite for correctly indicating and interpreting this test method, but also an awareness of these additional factors.

Recent advances in drug-induced angioedema

Angioedema is the end result of deep dermal, subcutaneous and/or mucosal swelling, and is potentially a life-threatening condition in cases where the pharynx or larynx is involved. Drug-induced angioedema has been reported to occur in response to a wide range of drugs and vaccines. Drug-induced angioedema, like other cutaneous drug reactions, has been reported to be most frequently elicited by beta-lactam antibiotics and non-steroidal anti-inflammatory drugs, although reliable data from epidemiologic studies are scarce. Recent reports suggested an increasing role of angiotensin-converting enzyme inhibitors (ACEIs) in the causation of life-threatening angioedema. ACEI-related angioedema is never accompanied by urticaria and occurs via a kinin-dependent mechanism. ACEI-related angioedema not only can start years after beginning the treatment, but it can then recur irregularly while under that treatment. Furthermore, allergy tests are unreliable for the diagnosis of ACEI-related angioedema, and so the relationship between angioedema and ACEIs is often missed and consequently quite underestimated. Accordingly, better understanding of the kinin-dependent mechanism, which is particular to angioedema, is necessary for the appropriate management of drug-induced angioedema.

Current view on nasal polyps management in Samter's triad patients

The nasal polyps associated with Samter's triad are often very extensive, difficult to treat, with great tendency to recurrence. In this paper the current opinion on nasal polyps management in aspirin triad patients was presented.

PATHOGENESIS

Opinions on pathogenesis of these disease was remembered as well as its epidemiology.

DIAGNOSTIC METHODS

The available diagnostic methods were presented. Treatment options: The available preservative treatment options was analyzed including aspirin desensitization. The role of surgical treatment, functional endoscopic sinus surgery was analyzed.

Immunologic evaluation of drug allergy

Hypersensitivity drug reactions (HDR) consist of an individual abnormal response with the involvement of the immunological system. In addition to specific immunological mechanisms where specific antibodies or sensitised T cells participate, release of inflammatory mediators by non-specific immunological recognition may also occur. Within this category are one of the most common groups of drugs, the non-steroidal anti-inflammatory drugs. In addition to chemical drugs new emerging ones with an increasing protagonism are biological agents like humanised antibodies and others. For IgE dependent reactions both in vivo and in vitro tests can be used for the immunological evaluation. Sensitivity of these is not optimal and very often a drug provocation test must be considered for knowing the mechanism involved and/or establishing the diagnosis. For non-immediate reactions also both in vivo and in vitro tests can be used. Sensitivity for in vivo tests is generally low and in vitro tests may be needed for the immunological evaluation. Immunohistochemical studies of the affected tissue enable a more precise classification of non-immediate reactions. The monitorization of the acute response of the reactions has given clues for understanding these reactions and has promising results for the future of the immunological evaluation of HDR.

Pathogenic Mechanisms and In Vitro Diagnosis of AERD

Aspirin-exacerbated respiratory disease (AERD) refers to chronic rhinosinusitis, nasal polyposis, bronchoconstriction, and/or eosinophilic inflammation in asthmatics following the exposure to nonsteroidal anti-inflammatory drugs (NSAIDs). A key pathogenic mechanism associated with AERD is the imbalance of eicosanoid metabolism focusing on prostanoid and leukotriene pathways in airway mucosa as well as blood cells. Genetic and functional metabolic studies on vital and non-vital cells pointed to the variability and the crucial role of lipid mediators in disease susceptibility and their response to medication. Eicosanoids, exemplified by prostaglandin E(2) (PGE(2)) and peptidoleukotrienes (pLT), are potential metabolic biomarkers contributing to the AERD phenotype. Also other mediators are implicated in the progress of AERD. Considering the various pathogenic mechanisms of AERD, a multitude of metabolic and genetic markers is suggested to be implicated and were introduced as potential biomarkers for in vitro diagnosis during the past decades. Deduced from an eicosanoid-related pathogenic mechanism, functional tests balancing PGE(2) and pLT as well as other eicosanoids from preferentially vital leukocytes demonstrated their applicability for in vitro diagnosis of AERD.

Flow Cytometry-Assisted Basophil Activation Test as a Safe Diagnostic Tool for Aspirin/NSAID Hypersenstivity

Purpose

Aspirin and non-steroidal anti-inflammatory drugs (ASA/NSAIDs) are common causes of drug hypersensitivity. An oral provocation test is the only definitive diagnostic test. This study assessed the reliability of a flow cytometry-assisted basophil activation test (FAST) as a safe diagnostic method for ASA/NSAID-induced hypersensitivity, as its high sensitivity and specificity have been demonstrated for many other drugs.

Methods

Eighteen patients and 11 controls were enrolled. Using a Flow-CAST kit® (Bühlmann Laboratories AG, Schönenbuch, Switzerland), 29 analyses with aspirin, ibuprofen, and diclofenac were performed by flow cytometry to detect double-positive staining of anti-IgE and anti-CD63. The stimulation index was defined as the activated basophil percentage after drug stimulation/basally active basophil percentage. A stimulation index≥2 and an absolute activated basophil percentage≥5 were considered positive.

Results

Patients with hypersensitivity to ASA/NSAIDs were predominantly female, and the prevalence of atopy was higher in patients than in controls. A sensitivity of 61%, specificity of 91%, positive predictive value of 92%, and negative predictive value of 59% were achieved.

Conclusions

FAST is a useful additional method for diagnosis of hypersensitivity reactions to ASA/NSAIDs. Further development is required to increase the sensitivity of the test.

[Cellular in-vitro assays. Applicability in daily routine]

Cellular in-vitro assays are able to detect antigen-dependent cellular processes without any risk for the patient. After antigen stimulation, both the cellular antigen stimulation test assessing sulfidoleukotriene production in leukocyte suspension, and flow cytometric basophil activation assays determining surface activation markers (CD63, CD203c), represent accepted models for in-vivo mast cell stimulation particularly in IgE-dependent reactions of immediate type. The value of these assays should be estimated considering the type of antigen and further diagnostic options. Most studies can not be compared due to different allergen concentrations, conditions of stimulation, methods, and defined cut-offs. Therefore, it is difficult to evaluate published evidence. Because of the logistic effort, cellular assays are often available only in specialized laboratories. However, in daily routine they are important in cases with clear-cut history but negative conventional allergy diagnostic procedures, in case of rare allergens (drugs, exotic food), as well as contraindications for skin and/or provocation test (hymenoptera venom allergy, anaphylaxis).

[Aspirin-Intolerance-Syndrom : a common and interdisciplinary disease]

The full clinical picture of aspirin intolerance - the association of aspirin-induced bronchial asthma, aspirin sensitivity and nasal polyps - has been described as Morbus Widal or later as the "Samter triad". Today the term Aspirin-exacerbated respiratory disease (AERD) is preferred to account for the progressive nature of this inflammatory airway condition with its unrelenting course even in the absence of non steroidal anti-inflammatory drugs (NSAID). This acquired idiosyncrasy appears to be related to an abnormal arachidonic acid metabolism. Epidemiological data suggests that 10% of all asthmatics do react with life-threatening asthma-attacks after the ingestion of aspirin (ASA) or other NSAID. Some asthmatics with nasal polyposis have been reported to suffer from aspirin intolerance. Although the exact mechanism is still unclear, it is unlikely that the pathogenesis is IgE-mediated. Patients often report chronic nasal obstruction, hyposmia, chronic rhinorrhoea, orbital edema and urticaria with flushing after the ingestion of NSAID. While a typical history and endoscopic findings can be suggestive of AERD, a definite diagnosis relies on appropriate challenge tests. AERD is often refractory to standard asthma treatment with systemic and inhaled steroids, β(2)-agonists, leukotrien-antagonists. Adaptive desactivation can induce a reversible tolerance to NSAID which also leads to an improvement in signs and symptoms of the underlying AERD.

Early detection of allergic diseases in otorhinolaryngology

Asthmatic diseases have been reported since the ancient world. Hay fever for instance, was described for the first time in the late 18(th) century, and the term "allergy" was introduced about 100 years ago. Today the incidence of allergies is rising; almost one third of the Western population suffers from its side effects. Allergies are some of the most chronic medical complaints, which results in high health expenditures. Therefore, they have a large health and political relevance.Caused by genetic and environmental factors, the group of IgE mediated allergies is large. It consists of e.g. atopic dermatitis, allergic asthma or allergic rhinitis. This paper aims to emphasize the ways of early diagnosis of allergic rhinitis (AR) as AR represents the most important representative of allergic diseases in ENT.

Effect of in vitro aspirin stimulation on basophils in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Basophil activation has been implicated in the pathogenesis of aspirin-exacerbated respiratory disease (AERD). However, a comprehensive analysis of basophil responses to aspirin in terms of mediator release, cytokine secretion and increased expression of surface activation markers has not been performed.

OBJECTIVE

To study the in vitro effects of aspirin on the concurrent release of histamine, leukotriene C4 (LTC4) and IL-4 from human basophils and to also evaluate changes in surface activation markers (CD63, CD69 and CD203c) expressed by these cells.

METHODS

Basophil-enriched cell suspensions from 10 patients with AERD and 10 healthy volunteers were incubated with lysine-aspirin for up to 3 h. Cells were analysed for expression of CD63, CD69 and CD203c using flow cytometry. Cell-free supernatants were evaluated for histamine, and LTC4 release and for IL-4 secretion.

RESULTS

Aspirin-induced expression of CD63, CD69 and CD203c yielded 30%, 80% and 70% sensitivity, respectively, but with poor specificity. There was no significant difference in LTC4 synthesis between groups. None of the patients with AERD (or controls) released IL-4 in response to aspirin. A higher dose of 5 mg/mL aspirin-mediated non-specific effects on basophils.

CONCLUSION

Basophil responses to in vitro aspirin challenge are poor indicators of clinical sensitivity. Aspirin activates some basophils by means of mechanisms that differ from the classical IgE-mediated pathway. Our study also shows that the use of 27 mm of aspirin (5 mg/mL) by previous investigators causes non-specific basophil activation, thereby eliminating its usefulness in a cell-based diagnostic test for AERD. Evaluation of in vitro basophil activation has low clinical value in identifying aspirin-induced respiratory reactions.

Salicylate intolerance: pathophysiology, clinical spectrum, diagnosis and treatment

INTRODUCTION

Acetylic salicylic acid (aspirin) intolerance relates to altered generation and metabolism of arachidonic acid and eicosanoids, and prostaglandins and leukotrienes ingestion of salicylates or COX-inhibitors.

METHODS

Selective review of literature in PubMed and the Cochrane Library.

RESULTS

Rhinitis, asthma and nasal polyposis are typical presentations, but urticaria and gut inflammation are also described. The mechanism involves a specific reaction to COX inhibitor substances in analgesics, cosmetics or plants resulting in an abnormal pattern of eicosanoids (prostaglandins and leucotrienes). The diagnosis is based on symptoms occurring immediately following ingestion of these substances or on refractory polyp formation. Blood tests may be helpful in unclear cases. Avoidance of triggering agents is helpful. Corticosteroids are the mainstay of pharmacological treatment. Biological, desensitization treatment involving the administration of increasing amounts of acetylic salicylic acid may also be used.

DISCUSSION

Asthma, rhinitis and nasal polyps, as well as chronic gastrointestinal irritation and urticaria following acetylic salicylic acid ingestion may suggest intolerance.

Lipoxin A4 levels in asthma: relation with disease severity and aspirin sensitivity

BACKGROUND

Lipoxin (LX) A4, an endogenous anti-inflammatory eicosanoid, has been found to be low in patients with severe asthma. However, few studies also suggested more diminished LX A4 levels in aspirin-exacerbated respiratory disease (AERD) when compared with aspirin-tolerant asthma (ATA). It is, therefore, currently not clear whether the asthma severity or the presence of AERD has a primary role in the disturbed LX metabolism.

OBJECTIVE

To detect LX A4 and 15-epi-LX A4 levels in asthma patients with and without AERD of comparable severity.

METHODS

The study groups consisted of 22 subjects with AERD, 22 subjects with ATA and 10 volunteers without asthma and aspirin sensitivity. Whole-blood samples were stimulated with calcium ionophore, A23187 (5 x 10(-5) m) and A23187 (5 x 10(-5) m)+aspirin (10(-4) m). LX A4 and 15-epi-LX A4 levels were analysed by the enzyme immune assay method.

RESULTS

Severe asthma patients in both AERD [0.5 (0.8)] ng/mL and ATA [0.5 (0.45) ng/mL] groups showed diminished generation for LX A4 to stimulation with A23187 in comparison with other severity degrees in their groups (P=0.02 and 0.046, respectively). LX A4 generation in both severe groups was comparable with each other (P>0.05). Although severe cases with AERD showed a diminished capacity to generate 15-epi-LX A4, this did not reach statistical significance.

CONCLUSION

This study indicated that diminished LX A4 generation was unique to severe asthma phenotype regardless of comorbid aspirin sensitivity. Clinical Implications Lower LX A4 levels in severe asthma would suggest a possibility for LX analogues as future treatment options in these patients.

Immediate-type allergy to drugs and related compounds: evaluation and management

Adverse drug reactions (ADR) constitute a major health issue in outpatient and inpatient clinical settings. An allergic drug reaction is an immunologically mediated adverse drug reaction that exhibits specificity and recurrence on re-exposure to the offending and/or cross-reactive compound(s). Diagnosis of drug allergy is difficult, as a broad spectrum of different drugs can elicit various immune-mediated diseases with distinct (sometimes unclear) pathomechanism, the exact structure (epitope) that causes the reaction is frequently unknown, the presence of an in vitro or in vivo test results might not be predictive of a clinical situation, and the gold standard or reference test for diagnosis, the drug challenge, is a complicated and sometimes dangerous endeavour. Nevertheless, during the past few years serious attempts have been made to standardise and validate in vitro and in vivo techniques for the diagnosis of drug allergy. New techniques, e.g. flow-assisted analysis of in vitro basophil activation, are replacing older ones like histamine release for immediate-type hypersensitivity reactions. However, additional comprehensive studies are required to further validate the technique and allow its entrance in mainstream diagnostic use, particularly for non-IgE-mediated hypersensitivity. This review attempts to summarize the major causes of immediate hypersensitivity reactions to drugs and related compounds. Special attention is paid to the diagnostic and therapeutic management of this common iatrogenic complication.

Aspirin-triggered 15-HETE generation in peripheral blood leukocytes is a specific and sensitive Aspirin-Sensitive Patients Identification Test (ASPITest)

BACKGROUND

We have previously demonstrated that aspirin triggers specific generation of 15-hydroxyeicosateraenoic acid (15-HETE) from nasal polyp epithelial cells and peripheral blood leukocytes (PBL) from aspirin-sensitive (AS) but not aspirin-tolerant (AT) patients with asthma/rhinosinusitis. The goal of this study was to assess the diagnostic value of ASA-induced 15-HETE generation measurement to identify AS patients.

METHODS

PBL were obtained from 43 AS patients with asthma and rhinosinusitis, 35 AT asthmatics and 17 healthy control (HC) subjects. PBL were incubated with 2-200 muM aspirin (ASA) and 15-HETE release was measured in cell supernatants with competitive ELISA.

RESULTS

Unstimulated PBL from all three groups of patients generated similar amount of 15-HETE. Incubation with 200 microM ASA resulted in an increase in an 15-HETE generation (mean increase +421%) in AS-asthmatics but small and nonsignificant response in AT-asthmatics or control subjects. Receiver operating curve (ROC) analysis revealed that the sensitivity of the test for confirmation of ASA-sensitivity was 83% and the specificity 82%. Positive predictive value was 0.79 and negative predictive value was 0.86. Naproxen induced a significant increase in 15-HETE only in some AS-asthmatics, but not in AT-asthmatics.

CONCLUSION

Our data demonstrate that ASA-induced 15-HETE generation by PBL is a specific and sensitive aspirin-sensitive patients identification test (ASPITest).

Drug-induced urticaria

Urticaria is characterised by transient swellings of the skin, which fluctuate over hours. Deeper swellings of the subcutaneous and submucosal tissue are known as angio-oedema. Drug-induced urticaria has been reported with a wide range of drugs and vaccines. NSAIDs and antibiotics are the drugs most commonly associated with urticaria, although reliable data from prospectively controlled studies is scarce. Spontaneous reports of drug-induced urticaria to the Committee on Safety of Medicines, UK, over a 40-year period also implicate bupropion, selective serotonin re-uptake inhibitor antidepressants, angiotensin-converting enzyme inhibitors (ACEI), H2 and H1 antihistamines, and systemic antifungals. New evidence suggests that selective COX-2 inhibitors may be tolerated in patients with aspirin-sensitive urticaria. The safety of angiotensin II receptor antagonists in patients with angio-oedema induced by ACEI has not yet been established.

The flow-cytometric determination of basophil activation induced by aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) is useful for in vitro diagnosis of the NSAID hypersensitivity syndrome

BACKGROUND

Hypersensitivity reactions to non-steroidal anti-inflammatory drugs (NSAIDs), manifested by cutaneous symptoms and/or airway manifestations represent 20-25% of all hypersensitivity reactions to drugs. Today, it is still claimed that no in vitro diagnostic tests exist for that condition and that the only way to confirm the diagnosis is a provocation challenge.

OBJECTIVE

The objective of this study was to assess whether NSAIDs may provoke blood basophil activation in vitro in such patients, as detected by a flowcytometric technique.

METHODS

Sixty NSAID hypersensitive patients (38 with cutaneous, 20 with airway and two with cutaneous and airway symptoms) and 30 control patients (15 asthmatics) were selected. Their hypersensitivity was confirmed by documented history indicating at least two clinical episodes to two or more different NSAIDs or by positive oral provocation challenge. Isolated buffy coat leukocytes were stimulated in vitro with aspirin, paracetamol, metamizol, diclofenac, and naproxen. The percentage of activated basophils was evaluated by an anti-CD63.

RESULTS

Aspirin showed a sensitivity of 43.3%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.4%. For the other NSAIDs, the sensitivity and specificity values were: 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%. When considering the first four NSAIDs, the global sensitivity raised to 63.3% and specificity to 93.3%. If the number of tests is to be limited for practical reasons, the combination of acetylsalicylic acid and diclofenac at two concentrations yields a sensitivity of 58.3% and a specificity of 93.3%.

CONCLUSIONS

Flowcytometric determinations of basophil activation following stimulation with NSAIDs show a high sensitivity (60-70%) with specificity above 90%. So this test may help avoiding some cumbersome and dangerous provocation challenges.

A new combined test with flowcytometric basophil activation and determination of sulfidoleukotrienes is useful for in vitro diagnosis of hypersensitivity to aspirin and other nonsteroidal anti-inflammatory drugs

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.

Allergen-induced mediator release tests

The diagnosis of allergic reactions in clinical practice is based on both clinical history and the determination of specific immunoglobulin E (IgE), either in the serum or on skin mast cells. However, for various reasons, identification of the causative factors is not possible in all the cases. Moreover, not all allergies are IgE-dependent. In an attempt to find sensitive, specific and cost-effective methods to investigate hypersensitivity reactions, in vitro tests were developed at a very early stage. Allergen-induced mediator release assays analyze the mediator released from effector cells, mainly peripheral blood cells, when stimulated in vitro with serial dilutions of the putative allergens. Described initially as research tools, they could well become diagnostic tests. However, relatively few high quality reports have been published so far. In this review, we will detail allergen-dependent histamine, tryptase, arachidonic acid metabolite, e.g. cysteinyl leukotrienes and 15-hydroxyeicosatetraenoic mediator release tests.

Aspirin-induced asthma: advances in pathogenesis, diagnosis, and management

In some asthmatic individuals, aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygen-ase 1 (COX-1) exacerbate the condition. This distinct clinical syndrome, called aspirin-induced asthma (AIA), is characterized by an eosinophilic rhinosinusitis, nasal polyposis, aspirin sensitivity, and asthma. There is no in vitro test for the disorder, and diagnosis can be established only by provocation challenges with aspirin or NSAIDs. Recent major advances in the molecular biology of eicosanoids, exemplified by the cloning of 2 cysteinyl leukotriene receptors and the discovery of a whole family of cyclooxygenase enzymes, offer new insights into mechanisms operating in AIA. The disease runs a protracted course even if COX-1 inhibitors are avoided, and the course is often severe, many patients requiring systemic corticosteroids to control their sinusitis and asthma. Aspirin and NSAIDs should be avoided, but highly specific COX-2 inhibitors, known as coxibs, are well tolerated and can be safely used. Aspirin desensitization, followed by daily aspirin treatment, is a valuable therapeutic option in most patients with AIA, particularly those with recurrent nasal polyposis or overdependence on systemic corticosteroids.

NSAID-induced urticaria and angioedema: a reappraisal of its clinical management

Hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs), resulting in urticaria and angioedema, is being observed with increasing frequency. Prevalence rates range from 0.1-0.3%, which is partly due to the large size of the exposed (at risk) population. Some predisposing factors for these cutaneous reactions have been identified, among them atopic diathesis, female sex, young adulthood, a history of chronic urticaria and the use of the NSAID for the relief of acute pain. The description of two different arachidonic acid cyclo-oxygenases (COX) about a decade ago, designated COX-1 and COX-2, and the incorporation into the therapeutic armamentarium of more selective enzyme inhibitors for the control of inflammation and pain, has led to an improved understanding of the pathogenesis of adverse reactions to NSAIDs. This has allowed investigators to study 'sensitive' individuals to see if they can safely receive these new pharmaceutical compounds. The reasons why some people react to NSAIDs are not completely clarified. The prevalent theory about the pathogenesis of urticaria and angioedema due to NSAIDs in cross-reactive patients assumes that the inhibition of COX-1 leads to a shunting of arachidonic acid metabolism towards the 5-lipoxygenase pathway, which results in an increased synthesis and release of cysteinyl leukotrienes. Although COX-2 inhibitors are well tolerated by the majority of classic NSAID-sensitive patients, cutaneous reactions to highly selective inhibitors of COX-2 have been described in some of these individuals, casting some doubts about the relevance of such hypotheses. On the other hand, in patients who react to a single NSAID and chemically similar products (single-reactors), specific immunoglobulin E antibodies to haptenated NSAID metabolites have been suspected, although these metabolites are not easily demonstrated by means of routine in vivo or in vitro techniques. Facial (periorbital) angioedema constitutes the most common form of clinical presentation, and one-third of the patients show a mixed clinical pattern of cutaneous (urticaria and/or angioedema) and respiratory symptoms which include upper respiratory tract edema, rhinorrhea, cough, breathlessness and tearing. When necessary, diagnosis is confirmed by means of controlled peroral drug challenges done by experienced physicians in the hospital setting and test results are helpful for clinical management, which will be based on strict avoidance, and the use of alternative tolerated medications. This approach is specially indicated in hypersensitive patients with chronic medical conditions who require continuous NSAID therapy, such as those with arthritis and coronary heart disease.

Effects of non-steroidal anti-inflammatory drugs on cyclo-oxygenase and lipoxygenase activity in whole blood from aspirin-sensitive asthmatics vs healthy donors

1. Cyclo-oxygenase (COX) and lipoxygenase (LO) share a common substrate, arachidonic acid. Aspirin and related drugs inhibit COX activity. In a subset of patients with asthma aspirin induces clinical symptoms associated with increased levels of certain LO products, a phenomenon known as aspirin-sensitive asthma. The pharmacological pathways regulating such responses are not known. 2. Here COX-1 and LO activity were measured respectively by the formation of thromboxane B(2) (TXB(2)) or leukotrienes (LT) C(4), D(4) and E(4) in whole blood stimulated with A23187. COX-2 activity was measured by the formation of prostaglandin E(2) (PGE(2)) in blood stimulated with lipopolysaccharide (LPS) for 18 h. 3. No differences in the levels of COX-1, COX-2 or LO products or the potency of drugs were found in blood from aspirin sensitive vs aspirin tolerant patients. Aspirin, indomethacin and nimesulide inhibited COX-1 activity, without altering LO activity. Indomethacin, nimesulide and the COX-2 selective inhibitor DFP [5,5-dimethyl-3-(2-isopropoxy)-4-(4-methanesulfonylphenyl)-2(5H)-furanone] inhibited COX-2 activity. NO-aspirin, like aspirin inhibited COX-1 activity in blood from both groups. However, NO-aspirin also reduced LO activity in the blood from both patient groups. Sodium salicylate was an ineffective inhibitor of COX-1, COX-2 or LO activity in blood from both aspirin-sensitive and tolerant patients. 4. Thus, when COX activity in the blood of aspirin-sensitive asthmatics is blocked there is no associated increase in LO products. Moreover, NO-aspirin, unlike other NSAIDs tested, inhibited LO activity in the blood from both aspirin sensitive and aspirin tolerant individuals. This suggests that NO-aspirin may be better tolerated than aspirin by aspirin-sensitive asthmatics.

Analgesics and asthma

The incidence of asthma is increasing throughout the world, which presents both public health and economic concerns. It is widely recognized that in some adult patients with asthma, aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygenase (COX)-1 exacerbate the condition. This is a distinct clinical syndrome called aspirin-induced asthma (AIA). The disease develops according to a characteristic pattern of symptoms. Persistent eosinophilic rhinosinusitis precedes development of nasal polyposis, aspirin hypersensitivity, and asthma. There is no in vitro test, and diagnosis can only be established by provocation tests with aspirin. At the biochemical level, AIA is characterized by a chronic overproduction of cysteinyl leukotrienes. The key enzyme, leukotriene C4 synthase, is overexpressed in bronchi, and its messenger RNA is upregulated in peripheral blood eosinophils. This can be partly related to the genetic polymorphism of the enzyme. The disease runs a protracted course, even if COX-1 inhibitors are avoided. The course of AIA is often severe, and at least half of the patients need systemic corticosteroids to control their asthma. To prevent life-threatening reactions, patients with AIA should avoid aspirin and other analgesics that inhibit COX-1. The incidence of cross-sensitivity to paracetamol in AIA patients is low and, when a reaction does occur, the symptoms experienced are shorter and milder than if the reactions were evoked by an NSAID. Rapidly growing evidence indicates that highly specific COX-2 inhibitors, known as coxibs, are well tolerated and can be safely used by AIA patients.

Drug eruptions and other adverse drug effects in aged skin

The elderly are at higher risk for suffering the annoying and hazardous skin reactions that are associated with drug therapy. If a serious reaction occurs, the aged are also at higher risk for major morbidity and mortality compared with younger individuals. Early consideration of a drug cause and prompt cessation of all potentially associated drugs may improve a patient's outcome. Thus, a prompt, careful, and accurate characterization of a drug-related reaction is important in optimizing patient care, along with close monitoring for associated internal toxicities and other medical complications of severe cutaneous reactions.

Release of cysteinyl leukotrienes with aspirin stimulation and the effect of prostaglandin E(2) on this release from peripheral blood leucocytes in aspirin-induced asthmatic patients

BACKGROUND

The decrease in prostaglandin E(2) (PGE(2)) release due to aspirin (ASA)-induced cyclooxygenase inhibition and the increment in cysteinyl leukotriene (Cys-LT) release secondary to the removal of the inhibitory effect of PGE(2) on Cys-LT release have been suggested in the pathogenesis of aspirin-induced asthma (AIA).

OBJECTIVE

In this study, we aimed to investigate the in vitro release of Cys-LT and to determine the effect of PGE(2) on Cys-LT release from peripheral blood leucocytes of patients with AIA after stimulation by ASA.

PATIENTS AND METHODS

Patients with AIA (n = 13), patients with ASA-tolerant asthma (ATA) (n = 12) and healthy volunteers as controls (n = 13) were included to the study. ASA and PGE2 at three different concentrations were applied to the peripheral blood leucocytes of the study group, and Cys-LT levels following stimulants were assessed by enzyme immunoassay method.

RESULTS

There was no difference in baseline Cys-LT levels between groups (AIA 353.4 +/- 55.5 pg/mL, ATA 354.7 +/- 40.3 pg/mL, and control group 368.5 +/- 30.2 pg/mL; P > 0.05). Though not present in other groups, the Cys-LT level of 453.6 +/- 70.0 pg/mL following ASA stimulation was higher than baseline in patients with AIA (P = 0.04). When PGE(2) was added to the ASA-stimulated samples of patients with AIA, Cys-LT levels were measured as 298.7 +/- 78.6 pg/mL, 279.8 +/- 79.9 pg/mL, and 243.4 +/- 51.3 pg/mL at PGE(2) 10(-7) m, 10(-6) m and 10(-5) m concentrations, respectively. These levels were lower than the ASA-stimulated Cys-LT values (P = 0.03, P = 0.01 and P = 0.01, respectively). The inhibitory effect of different PGE(2) concentrations on Cys-LT release was also present in patients with ATA and in controls.

CONCLUSION

The increase in Cys-LT levels following ASA stimulation seems to be unique to AIA, which was not present in patients with ATA and in healthy controls. The inhibitory effect of PGE(2) on stimulated Cys-LT levels is another important finding to elucidate the role of PGE(2) in the pathogenesis of AIA.

Cysteinyl-leukotriene release test (CAST) in the diagnosis of immediate drug reactions

BACKGROUND

The diagnosis of allergic reactions to drugs is difficult. Most skin tests are not standardized, and in vitro tests are needed to avoid provocation tests. Cross-linking of IgE on basophils is known to cause the release of both cysteinyl leukotriene (Cys-LT) and histamine. We aimed to evaluate the diagnostic utility (sensitivity, specificity, and efficiency) of measurement of sulfidoleukotrienes in drug allergy.

METHODS

We performed a prospective study in 55 patients with proven immediate adverse reactions to drugs (30 to beta-lactams, six to acetaminophen, and 19 to aspirin) and 64 drug-exposed nonallergic controls. Positive diagnosis was established by history, skin tests, and, if needed, oral provocation tests. Cys-LT release was determined after drug-allergen stimulation by the cellular antigen stimulation test (CAST(R)) technique. Histamine release was also assessed on the same samples by enzyme immunoassay. Spontaneous and anti-FcepsilonRIalpha-induced mediator release was also studied in all subjects. Sensitivity, specificity, and efficiency were calculated.

RESULTS

Net Cys-LT release was over the maximal threshold given by the manufacturer in 19/55 patients and in 9/64 controls. Net histamine release was over 5% of total histamine content in 28/55 patients and 34/64 controls. The efficiency of both tests was low.

CONCLUSION

Thus, in most cases, the in vitro Cys-LT test has little or no diagnostic utility and is not superior to histamine release.

A moderate and unspecific release of cysteinyl leukotrienes by aspirin from peripheral blood leucocytes precludes its value for aspirin sensitivity testing in asthma

Aspirin-induced asthma (AIA) is a clinical syndrome related to cysteinyl leukotriene overproduction in airways. The confirmation of the diagnosis requires inconvenient provocation tests with acetyl salicylic acid (ASA). A study was performed to evaluate whether measurement in vitro of cysteinyl leukotrienes (cys-LTs) release by isolated peripheral blood leucocytes, stimulated with ASA, can be of use for diagnosis of AIA. A cellular allergen stimulation test, CAST, was adapted to measure leukotriene release from leucocytes of 32 aspirin-tolerant and 26 aspirin-intolerant asthmatics. The cells were stimulated with Lys-ASA, N-formyl-methionyl-leucyl-phenylalanine (fMLP), or both fMLP and Lys-ASA, in a buffer containing IL-3, and results compared with human leukaemia cell line (Hl-60) response to Lys-ASA. Cys-LTs were measured in cell supernatant fluids by ELISA. ASA had a rather week stimulatory effect on cys-LTs release in both groups of patients. Contrary to some previous studies, no significant differences were found between cys-LTs release by leucocytes from AIA and ATA, or by differentiated Hl-60 cells. Measurement of cysteinyl-leukotriene release by peripheral blood leucocytes pre-treated with aspirin has no value for diagnosis of AIA.