EAACI guidelines on allergen immunotherapy: Hymenoptera venom allergy

Hymenoptera venom allergy is a potentially life-threatening allergic reaction following a honeybee, vespid, or ant sting. Systemic-allergic sting reactions have been reported in up to 7.5% of adults and up to 3.4% of children. They can be mild and restricted to the skin or moderate to severe with a risk of life-threatening anaphylaxis. Patients should carry an emergency kit containing an adrenaline autoinjector, H₁ -antihistamines, and corticosteroids depending on the severity of their previous sting reaction(s). The only treatment to prevent further systemic sting reactions is venom immunotherapy. This guideline has been prepared by the European Academy of Allergy and Clinical Immunology's (EAACI) Taskforce on Venom Immunotherapy as part of the EAACI Guidelines on Allergen Immunotherapy initiative. The guideline aims to provide evidence-based recommendations for the use of venom immunotherapy, has been informed by a formal systematic review and meta-analysis and produced using the Appraisal of Guidelines for Research and Evaluation (AGREE II) approach. The process included representation from a range of stakeholders. Venom immunotherapy is indicated in venom-allergic children and adults to prevent further moderate-to-severe systemic sting reactions. Venom immunotherapy is also recommended in adults with only generalized skin reactions as it results in significant improvements in quality of life compared to carrying an adrenaline autoinjector. This guideline aims to give practical advice on performing venom immunotherapy. Key sections cover general considerations before initiating venom immunotherapy, evidence-based clinical recommendations, risk factors for adverse events and for relapse of systemic sting reaction, and a summary of gaps in the evidence.

Registration of Diagnoses in the Danish National Registry of Patients

The data recorded in the National Registry of Hospitalized Patients in Denmark (Landspatient-registeret [LPR]) are based on reports from the somatic departments of hospitals throughout the country. For the purpose of evaluating the quality of these data, information from LPR concerning patient diagnoses was compared with corresponding information in the records from 924 consecutive admissions to the Frederiksborg County Hospital, Hiller0d. The diagnoses in these records were registered and given priority based on predetermined criteria for selection of primary and secondary diagnoses, respectively. For each hospitalized case a total of 4 primary and 4 secondary diagnoses might be registered. In order to show the variation in choice of diagnoses between physicians, all records from the two medical departments and 10% from the remaining departments were revised by two different physicians. In the medical “block” (medical departments B and F, and the departments of physical medicine, paediatrics, and neurology), there was agreement between the two physicians on at least one of the maximally 4 primary diagnoses which could be registered in 92% of the cases (2-digit code). For the surgical “block” (the departments of parenchymal surgery, orthopaedic surgery, gynaecology, and otology), the corresponding figure was 95%. If the two coders were in agreement on at least one primary diagnosis, this was identical with LPR’s primary diagnosis in 76% of the cases in the medical “block” and 85% of the cases in the surgical “block” (2-digit code). However, in the case of 15% of the medical and 7% of the surgical cases, the primary diagnosis, on which the two coders were in agreement, was not recorded at all by LPR (3-digit code).

It is to be emphasized that a certain variation between different physicians in their choice of diagnoses cannot be eliminated. In conclusion, the level of agreement between LPR and the study material found in the present study is in general satisfactory if LPR’s function as a basis of information for policy making in the hospital sector is taken into consideration. On the other hand, agreement (especially on medical records) is presumably not good enough in LPR to be used for research purposes.

Allergen immunotherapy for insect venom allergy: a systematic review and meta-analysis

BACKGROUND

The European Academy of Allergy and Clinical Immunology (EAACI) is in the process of developing the EAACI Guidelines on Allergen Immunotherapy (AIT) for the management of insect venom allergy. To inform this process, we sought to assess the effectiveness, cost-effectiveness and safety of AIT in the management of insect venom allergy.

METHODS

We undertook a systematic review, which involved searching 15 international biomedical databases for published and unpublished evidence. Studies were independently screened and critically appraised using established instruments. Data were descriptively summarized and, where possible, meta-analysed.

RESULTS

Our searches identified a total of 16 950 potentially eligible studies; of which, 17 satisfied our inclusion criteria. The available evidence was limited both in volume and in quality, but suggested that venom immunotherapy (VIT) could substantially reduce the risk of subsequent severe systemic sting reactions (OR = 0.08, 95% CI 0.03-0.26); meta-analysis showed that it also improved disease-specific quality of life (risk difference = 1.41, 95% CI 1.04-1.79). Adverse effects were experienced in both the build-up and maintenance phases, but most were mild with no fatalities being reported. The very limited evidence found on modelling cost-effectiveness suggested that VIT was likely to be cost-effective in those at high risk of repeated systemic sting reactions and/or impaired quality of life.

CONCLUSIONS

The limited available evidence suggested that VIT is effective in reducing severe subsequent systemic sting reactions and in improving disease-specific quality of life. VIT proved to be safe and no fatalities were recorded in the studies included in this review. The cost-effectiveness of VIT needs to be established.

Drug allergy passport and other documentation for patients with drug hypersensitivity - An ENDA/EAACI Drug Allergy Interest Group Position Paper

The strongest and best-documented risk factor for drug hypersensitivity (DH) is the history of a previous reaction. Accidental exposures to drugs may lead to severe or even fatal reactions in sensitized patients. Preventable prescription errors are common. They are often due to inadequate medical history or poor risk assessment of recurrence of drug reaction. Proper documentation is essential information for the doctor to make sound therapeutic decision. The European Network on Drug Allergy and Drug Allergy Interest Group of the European Academy of Allergy and Clinical Immunology have formed a task force and developed a drug allergy passport as well as general guidelines of drug allergy documentation. A drug allergy passport, a drug allergy alert card, a certificate, and a discharge letter after medical evaluation are adequate means to document DH in a patient. They are to be handed to the patient who is advised to carry the documentation at all times especially when away from home. A drug allergy passport should at least contain information on the culprit drug(s) including international nonproprietary name, clinical manifestations including severity, diagnostic measures, potential cross-reactivity, alternative drugs to prescribe, and where more detailed information can be obtained from the issuer. It should be given to patients only after full allergy workup. In the future, electronic prescription systems with alert functions will become more common and should include the same information as in paper-based documentation.

Self-medication of anaphylactic reactions due to Hymenoptera stings-an EAACI Task Force Consensus Statement

An anaphylactic reaction due to a Hymenoptera sting is a clinical emergency, and patients, their caregivers as well as all healthcare professionals should be familiar with its recognition and acute management. This consensus report has been prepared by a European expert panel of the EAACI Interest Group of Insect Venom Hypersensitivity. It is targeted at allergists, clinical immunologists, internal medicine specialists, pediatricians, general practitioners, emergency department doctors, and any other healthcare professional involved. The aim was to report the scientific evidence on self-medication of anaphylactic reactions due to Hymenoptera stings, to inform healthcare staff about appropriate patient self-management of sting reactions, to propose indications for the prescription of an adrenaline auto-injector (AAI), and to discuss other forms of medication. First-line treatment for Hymenoptera sting anaphylaxis is intramuscular adrenaline. Prescription of AAIs is mandatory in the case of venom-allergic patients who suffer from mast cell diseases or with an elevated baseline serum tryptase level and in untreated patients with a history of a systemic reaction involving at least two different organ systems. AAI prescription should also be considered in other specific situations before, during, and after stopping venom immunotherapy.

No evidence for contraindications to the use of propofol in adults allergic to egg, soy or peanut†

BACKGROUND

Propofol is thought to be a potential cause of allergic reactions in patients allergic to egg, soy or peanut, since current formulations contain an emulsion that includes egg lecithin and soybean oil. However, other than six case reports lacking in confirmatory evidence of an allergic reaction, there is no evidence linking the two types of allergies. The aim of this study was to examine the frequency of propofol allergy and to investigate if patients with specific immunoglobulin E (IgE) to egg, soy or peanut tolerated propofol.

METHODS

Study A examined the frequency of propofol allergy in 273 patients systematically investigated for suspected perioperative allergic reactions. Of these, 153 had been exposed to propofol and underwent skin tests and intravenous provocation. Study B retrospectively investigated propofol exposure and tolerance in 520 adult patients with a positive specific IgE to egg, soy or peanut.

RESULTS

Four of the 153 propofol-exposed patients (2.6%) investigated in study A were diagnosed with propofol allergy. Of these, three tested positive only on intravenous provocation. None of the four had allergic symptoms when eating egg, soy or peanut and none had detectable levels of specific IgE to egg or soy in their serum. In study B we found no signs of allergic reactions towards propofol in 171 retrieved anaesthetic charts from 99 patients with specific IgE to egg, soy or peanut.

CONCLUSION

No connection between allergy to propofol and allergy to egg, soy or peanut was found. The present practice of choosing alternatives to propofol in patients with this kind of food allergy is not evidence based and should be reconsidered.

Clinical and diagnostic features of perioperative hypersensitivity to cefuroxime

INTRODUCTION

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

METHOD

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

RESULTS

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

CONCLUSION

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

Drug hypersensitivity in clonal mast cell disorders: ENDA/EAACI position paper

Mastocytosis is a clonal disorder characterized by the proliferation and accumulation of mast cells (MC) in different tissues, with a preferential localization in skin and bone marrow (BM). The excess of MC in mastocytosis as well as the increased releasability of MC may lead to a higher frequency and severity of immediate hypersensitivity reactions. Mastocytosis in adults is associated with a history of anaphylaxis in 22-49%. Fatal anaphylaxis has been described particularly following hymenoptera stings, but also occasionally after the intake of drugs such as nonsteroidal anti-inflammatory drugs, opioids and drugs in the perioperative setting. However, data on the frequency of drug hypersensitivity in mastocytosis and vice versa are scarce and evidence for an association appears to be limited. Nevertheless, clonal MC disorders should be ruled out in cases of severe anaphylaxis: basal serum tryptase determination, physical examination for cutaneous mastocytosis lesions, and clinical characteristics of anaphylactic reaction might be useful for differential diagnosis. In this position paper, the ENDA group performed a literature search on immediate drug hypersensitivity reactions in clonal MC disorders using MEDLINE, EMBASE, and Cochrane Library, reviewed and evaluated the literature in five languages using the GRADE system for quality of evidence and strength of recommendation.

Standardized testing with chlorhexidine in perioperative allergy--a large single-centre evaluation

BACKGROUND

Perioperative allergic reactions to chlorhexidine are often severe and easily overlooked. Although rare, the prevalence remains unknown. Correct diagnosis is crucial, but no validated provocation model exists, and other diagnostic tests have never been evaluated. The aims were to estimate (i) the prevalence of chlorhexidine allergy in perioperative allergy and (ii) the specificity and sensitivity for diagnostic tests for chlorhexidine allergy.

METHODS

We included all patients investigated for suspected perioperative allergic reactions in the Danish Anaesthesia Allergy Centre during 2004-2012. The following tests were performed: specific IgE (Immunocap® ; Phadia AB, Sweden), histamine release test (HR) (RefLab ApS, Denmark), skin prick test (SPT) and intradermal test (IDT). Positivity criteria were as follows: specific IgE >0.35 kUA/l; HR class 1-12; SPT mean wheal diameter ≥3 mm; IDT mean wheal diameter ≥ twice the diameter of negative control. Chlorhexidine allergy was post hoc defined as a relevant clinical reaction to chlorhexidine combined with two or more positive tests. Based on this definition, sensitivity and specificity were estimated for each test.

RESULTS

In total, 22 of 228 patients (9.6%) met the definition of allergy to chlorhexidine. Estimated sensitivity and specificity were as follows: specific IgE (sensitivity 100% and specificity 97%), HR (sensitivity 55% and specificity 99%), SPT (sensitivity 95% and specificity 97%) and IDT (sensitivity 68% and specificity 100%).

CONCLUSIONS

In patients investigated for suspected perioperative allergic reactions, 9.6% were diagnosed with allergy to chlorhexidine. Using our definition of chlorhexidine allergy, the highest combined estimated sensitivity and specificity was found for specific IgE and SPT.

Transfusion-associated anaphylaxis during anaesthesia and surgery--a retrospective study

BACKGROUND AND OBJECTIVES

Transfusion-associated anaphylaxis (TAA) is a severe adverse reaction reported to occur in 1:9000-90,000 transfusions. According to the Danish Registration of Transfusion Risks (DART), the frequency is 1:300,000 transfusions, which suggests insufficient reporting of TAA in Denmark. Our aims were to identify possible cases of TAA, to characterize their symptoms and tryptase levels and to investigate the reporting of TAA to the haemovigilance systems.

MATERIAL AND METHODS

We reviewed 245 patients with suspected allergic reactions during anaesthesia and surgery, investigated at the Danish Anaesthesia Allergy Centre (DAAC). Based on the outcome of this investigation, the patients were classified as DAAC positive (confirmed hypersensitivity to identified agent, n = 112), or DAAC negative (no confirmed hypersensitivity, n = 133). Data on case history, details of blood transfusion and results of laboratory and clinical investigations were collected. TAA cases were identified according to the recommendations of the International Society of Blood Transfusion (ISBT).

RESULTS

Ten possible TAA cases (30% of all transfused patients) were identified, all DAAC negative. The frequency of elevated serum tryptase, hypotension and male sex was significantly higher among these cases compared with the remaining DAAC negative (P < 0·05), but not different from the DAAC-positive patients. One case had been reported to the Blood Bank haemovigilance system and none to DART.

CONCLUSION

We identified unreported cases of possible TAA, which resembled the DAAC-positive patients with respect to elevated tryptase and symptoms. By applying the ISBT criteria of adverse transfusion reactions, we conclude that TAA during anaesthesia and surgery is likely to be underreported in Denmark.

Skin test concentrations for systemically administered drugs -- an ENDA/EAACI Drug Allergy Interest Group position paper

Skin tests are of paramount importance for the evaluation of drug hypersensitivity reactions. Drug skin tests are often not carried out because of lack of concise information on specific test concentrations. The diagnosis of drug allergy is often based on history alone, which is an unreliable indicator of true hypersensitivity.To promote and standardize reproducible skin testing with safe and nonirritant drug concentrations in the clinical practice, the European Network and European Academy of Allergy and Clinical Immunology (EAACI) Interest Group on Drug Allergy has performed a literature search on skin test drug concentration in MEDLINE and EMBASE, reviewed and evaluated the literature in five languages using the GRADE system for quality of evidence and strength of recommendation. Where the literature is poor, we have taken into consideration the collective experience of the group.We recommend drug concentration for skin testing aiming to achieve a specificity of at least 95%. It has been possible to recommend specific drug concentration for betalactam antibiotics, perioperative drugs, heparins, platinum salts and radiocontrast media. For many other drugs, there is insufficient evidence to recommend appropriate drug concentration. There is urgent need for multicentre studies designed to establish and validate drug skin test concentration using standard protocols. For most drugs, sensitivity of skin testing is higher in immediate hypersensitivity compared to nonimmediate hypersensitivity.

Tolerability and efficacy of house dust mite AIT

Sublingual immunotherapy based on grass pollen allergy immunotherapy tablets is an efficacious and well-tolerated treatment for rhinoconjunctivitis, and subcutaneous house dust mite (HDM) immunotherapy is effective against allergic asthma. Three studies have investigated a new ALK tablet for HDM allergy: two studies on tolerability in adults and children, and one on efficacy and safety in adults and adolescents with asthma. Treatment was well tolerated, mainly with mild-to-moderate local reactions pertaining to the administration site, such as temporary oral pruritus. The primary efficacy endpoint was a significant reduction in inhaled corticosteroid dose compared to baseline after 1 year of daily treatment. A positive therapeutic effect on asthma was demonstrated by a reduction of more than 80 μg/day inhaled budesonide for a group receiving six developmental units daily compared to the placebo group.

Tolerability and efficacy of house dust mite AIT

Sublingual immunotherapy based on grass pollen allergy immunotherapy tablets is an efficacious and well-tolerated treatment for rhinoconjunctivitis, and subcutaneous house dust mite (HDM) immunotherapy is effective against allergic asthma. Three studies have investigated a new ALK tablet for HDM allergy: two studies on tolerability in adults and children, and one on efficacy and safety in adults and adolescents with asthma. Treatment was well tolerated, mainly with mild-to-moderate local reactions pertaining to the administration site, such as temporary oral pruritus. The primary efficacy endpoint was a significant reduction in inhaled corticosteroid dose compared to baseline after 1 year of daily treatment. A positive therapeutic effect on asthma was demonstrated by a reduction of more than 80 μg/day inhaled budesonide for a group receiving six developmental units daily compared to the placebo group.

The capsaicin cough reflex in patients with symptoms elicited by odorous chemicals

Patients with multiple chemical sensitivity and eczema patients with airway symptoms elicited by odorous chemicals have enhanced cough reflex to capsaicin when applying the tidal breathing method. The aims of the present study were to test whether the capsaicin induced cough reflex was enhanced when applying the single breath inhalation method in similar groups of patients with symptoms related to odorous chemicals e.g. other persons wearing of perfume; and to investigate to what extent the reporting of lower airway symptoms influenced the cough reflex. Sixteen patients fulfilling Cullen's criteria for multiple chemical sensitivity and 15 eczema patients with airway symptoms elicited by odorous chemicals were compared with 29 age-matched, healthy controls. We measured C5--the capsaicin concentration causing five coughs or more--using the single breath inhalation test. No difference was found between groups in age, body mass index or pulmonary function. The median C5 were 129 micromol/L (control group), 48 micromol/L (multiple chemical sensitivity patients), 32 micromol/L (eczema patients). The reporting of lower airway symptoms from odorous chemicals was significantly (p<0.05) correlated to increased cough reflex sensitivity to capsaicin, independent of patient group or co-existence of asthma. The results suggest that the C5 is not reliable for diagnosing MCS but C5 can be used to verify presence of lower airway symptoms related to odorous chemicals.

Increased release of histamine in patients with respiratory symptoms related to perfume

BACKGROUND

Environmental perfume exposure may cause respiratory symptoms. Individuals with asthma and perfume contact allergy report such symptoms more frequently than others. However, immunologic mechanisms have not been demonstrated and the symptoms are not associated with IgE-mediated allergy. The study aimed to investigate whether basophils from patients with respiratory symptoms related to perfume released more histamine in the presence of perfume as compared with healthy volunteers.

METHODS

Histamine release was measured by the glass fibre method. Blood was obtained from healthy volunteers (n=20) and patients with respiratory symptoms related to perfume (n=17) attending a dermatological outpatient clinic for patch testing. The effect of an international brand perfume was investigated using the basophil histamine release test with perfume. Furthermore, basophils from a healthy non-atopic donor were incubated with participant's sera and histamine release induced by perfume was measured.

RESULTS

In both groups incremental perfume concentrations showed a positive and significant (P<0.001) dose-response effect on the release of histamine. At the highest perfume concentration, the basophils released significantly (P<0.05) more histamine in patients as compared with healthy volunteers. No difference was found between the groups when sera were incubated with basophils from a healthy non-atopic donor.

CONCLUSION

Perfume induces a dose-dependent non-IgE-mediated release of histamine from human peripheral blood basophils. Increased basophil reactivity to perfume was found in patients with respiratory symptoms related to perfume.

The effectiveness of nationally implemented smoking interventions in Denmark

OBJECTIVE

The present study aimed to investigate the effectiveness of smoking cessation interventions at a national level.

METHOD

A systematic follow-up was made of 3628 adults who participated in smoking cessation groups or in individual interventions in different settings in Denmark from January 2001 to March 2002.

RESULTS

The rates of continued abstinence from smoking were estimated as 18% and 16% after 6 and 12 months, respectively, for the 3628 participants from 101 smoking cessation units. Among participants, who accomplished at least 75% of the intervention, the rates of non-smokers after six and twelve months were 23% and 19%, respectively. Five of the investigated factors influenced continued abstinence after 12 months: gender, age, degree of nicotine dependence, the format and the setting of the cessation service.

CONCLUSIONS

The study shows that it is possible to implement uniform smoking cessation interventions at a national level keeping the same abstinence rates as previously achieved in randomized clinical trials. The successful cessation interventions were run by nurses and equivalent staff that had received only 3 days of training and had no other particular therapeutic skills.

Scandinavian Clinical Practice Guidelines on the diagnosis, management and follow-up of anaphylaxis during anaesthesia

The present approach to the diagnosis, management and follow-up of anaphylaxis during anaesthesia varies in the Scandinavian countries. The main purpose of these Scandinavian Clinical Practice Guidelines is to increase the awareness about anaphylaxis during anaesthesia amongst anaesthesiologists. It is hoped that increased focus on the subject will lead to prompt diagnosis, rapid and correct treatment, and standardised management of patients with anaphylactic reactions during anaesthesia across Scandinavia. The recommendations are based on the best available evidence in the literature, which, owing to the rare and unforeseeable nature of anaphylaxis, mainly includes case series and expert opinion (grade of evidence IV and V). These guidelines include an overview of the epidemiology of anaphylactic reactions during anaesthesia. A treatment algorithm is suggested, with emphasis on the incremental titration of adrenaline (epinephrine) and fluid therapy as first-line treatment. Recommendations for primary and secondary follow-up are given, bearing in mind that there are variations in geography and resources in the different countries. A list of National Centres from which anaesthesiologists can seek advice concerning follow-up procedures is provided. In addition, an algorithm is included with advice on how to manage patients with previous suspected anaphylaxis during anaesthesia. Lastly, Appendix 2 provides an overview of the incidence, mechanisms and possibilities for follow-up for some common drug groups.

Side-effects of allergen-specific immunotherapy: a prospective multi-centre study

BACKGROUND AND OBJECTIVE

The safety of allergen-specific immunotherapy (SIT) is a parameter of great interest in the overall assessment of the treatment. A clinical database was developed in order to obtain early warnings of changes in the frequency and severity of side-effects and sufficient data for the evaluation of possible risk factors.

METHODS

During a 3-year period, four allergy centres in Copenhagen, Denmark, included data from all patients initiating SIT to a common database. Information on initial allergic symptoms, allergens used for treatment, treatment regimens and systemic side-effects (SSEs) during the build-up phase was collected.

RESULTS

A total of 1,038 patients received treatment with 1,709 allergens (timothy, birch, mugwort, house dust mite (HDM), cat, and wasp and bee venom), 23,047 injections in total. Most SIT patients completed the updosing phase without side-effects, but there was a significant difference between allergens: wasp (89%), birch (82%), HDM (81%), cat (74%) and grass (70%) (P=0.004). A total of 582 SSEs were registered in 341 patients. Most side-effects were mild grade 2 reactions (78%). A difference in severity between allergens was observed (P=0.02), with grass giving most problems. The type of allergen but not patient- or centre-related parameters seemed predictive of side-effects.

CONCLUSIONS

Allergen extracts differ in their tendency to produce side-effects. Multi-centre studies like the present one allow more patients to be evaluated, and thereby provide a more efficient surveillance of side-effects. Online Internet-based registration to a central national database of every allergen injection would be an even more powerful tool for evaluation of risk factors and surveillance of side-effects.

Exposure of eyes to perfume: a double-blind, placebo-controlled experiment

Environmental perfume exposure can elicit bothersome respiratory symptoms. Symptoms are induced at exposure levels which most people find tolerable, and the mechanisms are unclear. The aim of the study was to investigate patients with eye and respiratory symptoms related to environmental perfume, by exposing the eyes to perfume in a double-blind, placebo-controlled study.Twenty-one eczema patients with respiratory symptoms elicited by perfume were compared with 21 healthy volunteers in a sex- and age-matched case-control study. The participants completed a symptom questionnaire, and underwent a double-blind, placebo-controlled exposure to perfume. Of the 42 individuals tested, 10 had more eye symptoms (irritation, itching, and tears) during perfume exposure than during placebo exposures, and eight of these individuals (P = 0.07, Fisher's exact test) belonged to the patient group. A true positive eye reaction to perfume was significantly associated with identification of perfume as an active exposure (P < 0.05). In this study, vapor of perfume elicited irritation in the eyes independently of olfaction, but the relative importance of ocular chemoperception in relation to elicitation of respiratory symptoms from common environmental exposures to perfume remains unclear. We investigated the hypothesis of an association between respiratory symptoms related to perfume and ocular perfume sensitivity by exposing the eyes to perfume in a double blind, placebo-controlled experiment. Vapors of perfume provoked symptoms in the relevant eye in some patients and healthy control persons, but under our exposure conditions, ocular chemesthesis failed to elicit respiratory symptoms.

Diagnosis of Hymenoptera venom allergy

The purpose of diagnostic procedure is to classify a sting reaction by history, identify the underlying pathogenetic mechanism, and identify the offending insect. Diagnosis of Hymenoptera venom allergy thus forms the basis for the treatment. In the central and northern Europe vespid (mainly Vespula spp.) and honeybee stings are the most prevalent, whereas in the Mediterranean area stings from Polistes and Vespula are more frequent than honeybee stings; bumblebee stings are rare throughout Europe and more of an occupational hazard. Several major allergens, usually glycoproteins with a molecular weight of 10-50 kDa, have been identified in venoms of bees, vespids. and ants. The sequences and structures of the majority of venom allergens have been determined and several have been expressed in recombinant form. A particular problem in the field of cross-reactivity are specific immunoglobulin E (IgE) antibodies directed against carbohydrate epitopes, which may induce multiple positive test results (skin test, in vitro tests) of still unknown clinical significance. Venom hypersensitivity may be mediated by immunologic mechanisms (IgE-mediated or non-IgE-mediated venom allergy) but also by nonimmunologic mechanisms. Reactions to Hymenoptera stings are classified into normal local reactions, large local reactions, systemic toxic reactions, systemic anaphylactic reactions, and unusual reactions. For most venom-allergic patients an anaphylactic reaction after a sting is very traumatic event, resulting in an altered health-related quality of life. Risk factors influencing the outcome of an anaphylactic reaction include the time interval between stings, the number of stings, the severity of the preceding reaction, age, cardiovascular diseases and drug intake, insect type, elevated serum tryptase, and mastocytosis. Diagnostic tests should be carried out in all patients with a history of a systemic sting reaction to detect sensitization. They are not recommended in subjects with a history of large local reaction or no history of a systemic reaction. Testing comprises skin tests with Hymenoptera venoms and analysis of the serum for Hymenoptera venom-specific IgE. Stepwise skin testing with incremental venom concentrations is recommended. If diagnostic tests are negative they should be repeated several weeks later. Serum tryptase should be analyzed in patients with a history of a severe sting reaction.

Mucosal symptoms elicited by fragrance products in a population-based sample in relation to atopy and bronchial hyper-reactivity

BACKGROUND

Exposure to perfume and fragrance products may, in some individuals, cause symptoms from the eyes and airways. The localization, character and risk factors of such symptoms in the general population are unknown.

OBJECTIVE

To investigate both the localization and character of symptoms from the eyes and airways elicited by fragrance products, and the associations between such symptoms and skin prick test reactivity (atopy), methacholine bronchial hyper-reactivity (BHR), allergic rhinitis and asthma.

METHODS

A questionnaire on mucosal symptoms elicited by fragrance products was posted to 1189 persons who had participated in a Danish population-based study of allergic diseases in 1997/1998. The study included measurement of BHR, atopy, forced expiratory volume in 1 s (FEV1), and serum eosinophilic cationic protein (serum ECP).

RESULTS

The response rate was 79.6%. Symptoms from the eyes or airways elicited by fragrance products were reported by 42%. BHR (adjusted odds ratio 2.3, 95% confidence interval 1.5-3.5) was independently associated with symptoms from the eyes and airways elicited by fragrance products. There were no significant associations between these symptoms and atopy, FEV1 or serum ECP.

CONCLUSIONS

Mucosal symptoms from the eyes and airways were common in this population. BHR was a significant and independent predictor of these symptoms. The lack of association with atopy suggested that IgE-mediated allergic mechanisms do not play a major role in the development of these symptoms.

Airborne chemicals cause respiratory symptoms in individuals with contact allergy

Exposure to fragrance chemicals causes various eye and airway symptoms. Individuals with perfume contact allergy report these symptoms more frequently than individuals with nickel allergy or no contact allergies. However, the associations between contact allergy and respiratory symptoms elicited by airborne chemicals other than perfumes are unclear. The study aimed to investigate the association between eye and airway symptoms elicited by airborne chemicals (other than perfumes) and contact allergy in a population-based sample. A questionnaire on respiratory symptoms was posted, in 2002, to 1189 individuals who participated in 1997/1998 in a Danish population-based study of allergic diseases. Questions about eye and airway symptoms elicited by different airborne chemicals and airborne proteins were included in the questionnaire. Data from the questionnaire were compared with data on patch testing and prick testing. Having at least 1 positive patch test (adjusted odds ratio 1.7, 95% CI 1.2-2.5) was associated with the symptoms, and the odds ratio increased with the number of positive patch tests (P-value for test for trend <0.05). Bronchial hyperreactivity, female sex and psychological vulnerability were independently associated with symptoms, but no association was found between prick test reactivity to proteins and the symptoms elicited by airborne chemicals.

A link between skin and airways regarding sensitivity to fragrance products?

BACKGROUND

Exposure to volatile fragrances is commonplace and may be related to various eye and airway symptoms. Skin exposure to fragrances is known to cause perfume contact allergy and eczema, but it is unknown whether eye or airway symptoms elicited by fragrance products are associated with contact allergy or eczema.

OBJECTIVES

To investigate if eye and airway symptoms elicited by fragrance products are associated with perfume contact allergy or hand eczema in a population-based sample.

METHODS

A questionnaire on eye and airway symptoms elicited by fragrance products was mailed to 1189 individuals who had recently participated in a Danish population-based study of allergic diseases. Results from the questionnaire about localization and character of the symptoms were compared with data on patch testing and 1-year prevalence of hand eczema collected during the health examination.

RESULTS

Positive, independent and significant (P < 0.05) associations were found between eye and airway symptoms elicited by fragrance products and perfume contact allergy (adjusted odds ratios 2.0-3.7) and hand eczema (adjusted odds ratios 1.6-2.6). In further analysis, similar and consistent results were found regarding severity of the symptoms. No associations were found between nickel contact allergy and the symptoms. Female sex and psychological vulnerability were independently associated with eye and airway symptoms elicited by fragrance products, but adjustment in multivariate analysis did not change the results regarding perfume contact allergy and hand eczema.

CONCLUSIONS

Individuals with perfume contact allergy and/or hand eczema, as opposed to those without, have more frequent and more severe eye or airway symptoms after exposure to volatile fragrance products. Having hand eczema has the greatest impact on reporting eye and airway symptoms elicited by fragrance products.

House dust mites and their allergens at selected locations in the homes of house dust mite-allergic patients

BACKGROUND

Knowledge of the occurrence of house dust mites (HDM) and their allergens in domestic locations is important when planning intervention.

OBJECTIVE

The aim of this study was to describe the distribution of HDMs and their allergens before intervention in multiple locations in the homes of newly diagnosed HDM-allergic patients with a known high Der 1 concentration in their mattress dust.

METHODS

Dust was collected from ten locations in the homes of eight HDM-allergic patients. Dust was analysed for allergen content with ELISAs for Der f 1, Der p 1 and Der m 1; and HDM were counted. Total allergen concentrations ( micro g Der 1/g dust) were expressed as the sum of Der f 1, Der p 1 and Der m 1.

RESULTS

On mattresses the median concentration was 86 micro g Der 1/g dust (range 30-288) and 188 mites/g dust (range 12-1910). Der 1 exceeded 10 micro g/g dust in mattresses (8/8), duvets/pillows (3/8), a bedroom carpet (1/1), a living room carpet (1/6), upholstered furniture (2/8) and a curtain (1/5). Uncarpeted floors, upholstered furniture, bookshelves and walls had significantly lower Der 1 concentration than the mattresses. The relative contribution of Der p 1, Der f 1 or Der m 1 to Der 1 was related to homes, rather than to the location. Der m 1 only occurred in minute amounts.

CONCLUSION

For HDM intervention, our results indicate that priority should be given to the removal of allergens from mattresses, and in addition from carpets, duvets/pillows and upholstered furniture. Dust from walls, uncarpeted floors, bookshelves and curtains appear to contribute insignificantly to the domestic HDM allergen load.

Side-effects of insect venom immunotherapy: results from an EAACI multicenter study. European Academy of Allergology and Clinical Immunology

BACKGROUND

The effect of venom immunotherapy (VIT) is well documented, but fear of systemic side-effects (SE) may prevent its use. The study aimed to analyze the character and frequency of SE and risk factors.

METHODS

In a prospective study, 19 European centers included patients starting on VIT for systemic reactions to insect stings. Various dose regimens were applied.

RESULTS

Data from 840 patients with a total of 26 601 injections were obtained. Seventy-one percent were treated with Vespula-venom extract and 27% with honeybee-venom extract. Twenty percent of patients had SE corresponding to 1.9% of injections during dose increase and 0.5% during the maintenance phase. The vast majority of the 280 reactions were mild: only one-third required medical treatment. Injected or inhaled adrenaline was applied in six patients, of whom only one had a drop in blood pressure and collapse. Female sex, bee-venom extract, and rapid dose increase, but not severity of insect sting reactions, increased the risk of SE. The severity of SE was less in males but was not related to age, treatment phase, species of insect, or severity of insect sting reactions.

CONCLUSIONS

The frequency of SE was low, and the majority of these could be managed without treatment. Risk was increased in females, in bee-venom-treated patients, and in those with rapid dose increase.

Allergen-specific immunotherapy in birch- and grass-pollen-allergic rhinitis. II. Side-effects

BACKGROUND

Allergen-specific immunotherapy (IT) involves the risk of side-effects. Different side-effect profiles have been reported for different allergens, and it would be of great benefit to be able more precisely to predict patient- and allergen-related risk factors.

METHODS

Fifty-two patients with rhinoconjunctivitis and allergy to birch as well as grass pollen participated in a 3-year IT study, with a baseline year followed by 2 years of treatment. During the first treatment year, the patients received double-blinded IT with either birch (Betula verrucosa) or grass (Phleum pratense) pollen extracts adsorbed to aluminum hydroxide. The following year, the other allergen extract was added. Assessment of systemic reactions (SRs) was performed, and related to patient pretreatment parameters such as seasonal symptoms and medication requirement, skin prick test (SPT), conjunctival provocation test (CPT), nasal provocation test (NPT), total and specific IgE, basophil histamine release (HR), eosinophil count (EOS), eosinophil cationic protein (ECP), and eosinophil protein X (EPX).

RESULTS

In total, 44 and 47 patients started IT with birch- and grass-pollen extracts, respectively. All SRs occurred during the dose-increase phase. No life-threatening SRs were observed. There were a higher number of patients with SRs during IT with grass pollen than IT with birch pollen, 21 vs five patients (P<0.001), with SRs to 3.3% of grass-pollen injections compared to 0.7% of birch-pollen injections (P<0.0001). The SRs of birch-pollen IT were mild, consisting of rhinoconjunctivitis and oral-pharyngeal itching, whereas asthma and urticaria episodes were observed in the grass-pollen IT. No difference was found in sensitivity to birch and grass, when measured by SPT, CPT, NPT, specific IgE, or HR, and no difference was found in age, duration of allergic symptoms, prevalence of asthma, mean seasonal birch/grass symptom score, eye-drop use, or antihistamine or prednisolone intake between the group with and without subsequent SRs to IT. No difference was found in EOS, serum ECP, or EPX, between the group with and without subsequent SRs to IT.

CONCLUSIONS

IT with grass-pollen extract seems to be associated with a higher number and more severe SRs than birch-pollen IT. Neither demographic data nor diagnostic tests of allergy such as specific IgE, HR, SPT, CPT, and NPT could identify the patients with subsequent SRs.

Allergen-specific immunotherapy in birch- and grass-pollen-allergic rhinitis. I. Efficacy estimated by a model reducing the bias of annual differences in pollen counts

BACKGROUND

Evaluation of the efficacy of allergen-specific immunotherapy (IT) with pollen extracts is complicated by annual variation in pollen intensity. Our study aimed to evaluate the efficacy of birch and grass IT, taking into consideration these variations.

METHODS

After 1 year of observation, 52 patients with rhinoconjunctivitis and allergy to birch as well as grass pollen were allocated to double-blinded clustered IT with aluminum-adsorbed extract produced from either birch (Betula verrucosa) pollen or grass (PIleum pratense) pollen. After 1 year of treatment, the patients continued IT with their original extract and also received the other extract. During the three consecutive pollen seasons, the rhinoconjunctivitis symptom score and the use of antihistamines, eye-drops, and oral prednisolone were recorded. Longitudinal data analysis was used to investigate the relation between different pollen counts and the magnitude of clinical efficacy.

RESULTS

An effect of IT was found on symptom score, antihistamine intake, and eye-drop use for both birch and grass (P values <0.05). The mean reduction in symptom score/medication by IT ranged from 24% to 95%, depending on mean seasonal pollen counts. A minimum mean seasonal grass-pollen count of 20-30 pollen grains m3 was required for the efficacy of grass IT to emerge.

CONCLUSIONS

A model was developed for evaluation of efficacy in longitudinal IT studies, taking the differences in annual pollen counts into consideration. The model showed a significant beneficial role of pollen IT in rhinoconjunctivitis patients allergic to birch and grass pollen.

Effect of two different types of vacuum cleaners on airborne Fel d 1 levels

BACKGROUND

Vacuum cleaners may increase the level of airborne allergens by leakage through the cleaners or by disturbance of floor dust by the exhaust air produced.

OBJECTIVE

The aim of this study was to evaluate the short-term effect of vacuum cleaning with two different types of cleaners on airborne cat allergen analyzed by a biologic and by an immunochemical test.

METHODS

Ten homes with cats were cleaned in random order with a 1-week interval by a traditional canister type vacuum cleaner (T) and a semi-stationary vacuum cleaner (S) that conducts the air to the exterior through a valve in the wall. Airborne particles were collected by air sampling for 2 hours and cat allergen, Fel d 1, was quantified biologically by basophil histamine release test (HR test) and immunochemically by enzyme linked immunosorbent assay (ELISA).

RESULTS

Using the S resulted in smaller amounts of airborne cat allergen than the T (mean 2.1 ng/m3 air (range .8 to 12.5) versus 5.2 ng/m3 (1.3 to 13.3), P < .002 measured by ELISA). Results from ELISA and HR test correlated well (r = .91, P < .001).

CONCLUSIONS

The use of S with exhaust to the outside of the dwelling gave rise to less airborne low particle size allergen during the cleaning procedure than a T method. The basophil histamine release test could be a valid alternative method to establish allergen content in environmental samples especially in allergen systems with no available monoclonal antibodies.

[Allergy to dust mites]

House dust mites are the most important indoor allergens in our region. During recent years more dwellings have become infested, most likely as a result of increased indoor humidity due to reduced ventilation. Among Danish adults, 14% have developed IgE against mites. The allergens are stable and can remain for years. Keeping the humidity low (< 45%) during winter months is the most important limiting factor for mite growth. It can be accomplished by ventilation and heating. If bedding, pillow, eiderdown and covering mattress are washedat temperatures > 55 degrees C mites are killed and allergens removed. In addition mattress covers seem to be useful, although guidelines for quality assessment are lacking. Reduction in mite exposure will reduce development of allergy in all age groups especially in the newborn period. Immunotherapy can be offered in rhinitis and moderate asthma when sufficient allergen reduction cannot be accomplished.

[House dust mite allergens and mite allergy in Copenhagen dwellings. A cross-sectional study]

The aim of the study was to investigate the influence of various environmental factors on occurrence of house dust mite allergens and the influence of allergen exposure on mite allergy. Ninety-two persons from a population study filled in a questionnaire, were skin prick and lung function tested and dust samples were collected from their mattresses for analyses. Two out of five patients with asthma had a positive skin reaction to house dust mite allergen in contrast to five out of 87 non-asthmatics. Fifty-nine per cent of the dust samples contained (group 1) mite allergen > 2 micrograms/g dust. Such mattresses were older (median 7 years, range 1-22) than mattresses with less allergen (median 4 years, range 1-20). In the six bedrooms reported to be humid or mouldy, mattresses contained high concentration of mite allergens. No other parameter investigated could predict the allergen contents. In almost all cases dust analyses are crucial to be able to advise patients with house dust mite allergy.

Skin symptoms in patients with atopic dermatitis using enzyme-containing detergents. A placebo-controlled study

Detergent enzymes may cause skin irritation and occasionally hypersensitivity reactions. The potential hazards of these enzymes have led some physicians to advise atopic dermatitis patients against the use of enzyme-enriched detergents. A three-phased randomised, double-blind, cross-over experiment was designed to question this recommendation. Each period was of 1 month's duration. In the first phase patients continued using their normal washing detergent. In phase II patients used trial detergent with or without added enzymes, and during phase III patients were given the opposite trial detergent. A total of 25 patients completed the study. The primary efficacy parameters were inter-period changes in corticosteroid usage and changes in SCORAD. Secondary efficacy parameters were altered subjective symptoms scored during the final 2 weeks of each interval. Analyses of all data revealed no statistical differences in any of the primary or secondary parameters comparing treatment and placebo periods. Our data therefore seem to exclude that atopic dermatitis may exacerbate during 1 month's exposure to enzyme-enriched detergents. Since no significant irritant capacity was detected in atopic dermatitis patients, it is unlikely that consumers with "normal skin" will experience any skin discomfort when enzyme-enriched detergents are used.

Exposure chamber for allergen challenge. A placebo-controlled, double-blind trial in house-dust-mite asthma

Exposure chambers have proven to be valuable tools in the study of reactions to aeroallergens, and in monitoring the efficacy of antiallergic therapy. In the present study, 15 house-dust-mite-allergic asthmatics and five nonallergic volunteers were challenged in a recently developed exposure chamber. The trial was performed double-blinded with house-dust-mite allergen or placebo. Patients with allergy to house-dust mite (Dermatophagoides pteronyssinus) (Der p) were included by positive skin prick test, allergen-specific IgE, and conventional bronchial allergen challenge, with nebulizer and mouthpiece. In the exposure chamber, a total allergen dose corresponding to 1200 ng Der p 1 was applied. All participants kept diaries, recording peak expiratory flow rates, symptoms, and medication in periods of at least 2 weeks before and after each challenge. Twelve of the 15 asthmatics reacted with asthmatic symptoms with a median change in FEV1 of -16.4% when exposed to the allergen, but not to placebo, in the exposure chamber. Three patients had only minor symptoms during both chamber exposures and experienced no impairment of pulmonary function. Late-phase reactions were less frequent (one vs three) after the exposure chamber challenges, as compared to the traditional challenges. None of the healthy subjects reacted to the challenges. In conclusion, our exposure chamber was able to elicit symptoms in allergic subjects, and this ability was obtained with only minor amounts of house-dust-mite allergen. The described method could prove to be a more physiologically relevant model to monitor individual responses to aeroallergens.

Antihistamine premedication in specific cluster immunotherapy: a double-blind, placebo-controlled study

BACKGROUND

Specific immunotherapy treatment in allergic diseases involves a risk of systemic side effects. A double-blind, placebo-controlled study was performed in 45 patients allergic to pollen to determine whether pretreatment with loratadine could reduce the number and severity of systemic reactions during the dose-increase phase of cluster immunotherapy.

METHODS

The patients received cluster immunotherapy with a standardized birch (Betula verrucosa) or grass (Phleum pratense) pollen extract adsorbed to aluminum hydroxide. The immunotherapy schedule involved seven visits and 14 injections to reach a maintenance dose of 100,000 standardized quality units. Loratadine, 10 mg, or placebo tablets were administered 2 hours before the first injection at each visit.

RESULTS

A total of 720 injections were given (309 injections in 21 patients receiving loratadine and 411 injections in 24 patients receiving placebo). The median numbers of injections to reach maintenance dose were 15 (range, 14 to 18) in the loratadine group and 16 (range, 14 to 23) in the placebo group (p = 0.037). The numbers of patients with systemic reactions were seven (33%) and 19 (79%) in the loratadine and placebo groups, respectively (p = 0.002). Twenty-five reductions caused by systemic reactions were observed in the placebo group in contrast to nine in the loratadine group (p = 0.047). No life-threatening systemic reactions were observed in either group. Systemic reactions were, however, more severe in the placebo group, mainly because of a significantly higher incidence of urticaria (10 vs 1, p = 0.022).

CONCLUSION

Pretreatment with loratadine seems to reduce both the number and severity of systemic reactions in specific cluster immunotherapy.

Allergen-induced histamine release in intact human skin in vivo assessed by skin microdialysis technique: characterization of factors influencing histamine releasability

BACKGROUND

The purposes of the study were to characterize allergen-induced histamine release in intact human skin in vivo by using a novel microdialysis technique and to study covariates influencing histamine releasability.

METHODS

Hollow microdialysis fibers were inserted into the upper dermis in 15 timothy-sensitivity subjects. Up to 12 fibers were inserted in each subject. Each fiber was perfused with Krebs-Ringer's solution at a rate of 3.0 microliters/min. Three to four serial dilutions of allergen were applied to the skin by intracutaneous injections or skin prick test above individual fibers. Samples were collected in two 2-minute fractions before skin challenge and in 10 consecutive samples for 20 minutes after skin challenge. Histamine was assayed spectrofluorometrically.

RESULTS

A significant dose-response relationship for histamine release was demonstrated with intracutaneous tests and skin prick tests. The time to reach peak histamine release after an intracutaneous test was 4 to 8 minutes, compared with 12 to 14 minutes for a skin prick test. Histamine release correlated significantly with wheal size. Intrasubject coefficient of variation on histamine release was about 20%. A substantial intersubject variation in histamine releasability was observed. Seventy to seventy-five percent of the variation could be accounted for by a combination of gender, total and allergen-specific IgE, and an in vitro basophil histamine release test.

CONCLUSIONS

Using a skin microdialysis technique, we have described in detail histamine release in intact human skin by allergen. The microdialysis method proved to be a reproducible technique for monitoring histamine release in allergic skin reactions and for studying histamine releasability of skin mast cells in vivo.

Exposure chamber for allergen challenge. The development and validation of a new concept

Exposure chambers have proven to be valuable tools in studying allergic diseases. The chamber provides a controlled environment and maintains conditions for measuring the amount of allergen inducing symptoms in allergic subjects. The aim of the present study was to develop and test an exposure chamber. The chamber was constructed as an airtight tent, made of transparent polyethylene, easy to adapt to the shape of an existing room, easy to clean, and providing exact allergen-dosage control. Airflow to the interior of the tent was controlled by a variable inlet ventilator fitted with a micropore filter and balanced by a variable high-volume air-sampler on the outlet side. Trace material and allergen were administered as aerosols with a nebulizer connected to the inlet pipe. Samples were obtained from interior surfaces and filters at the outlet. Two different methods were used to test the concept. One method used a colored, neutral trace substance (phenol red indicator) measured photometrically on extracts from filters. Secondly, house-dust mite allergen (Dermatophagoides pteronyssinus) was applied, with samples analyzed by an ELISA technique. The results demonstrated the ability of the system to administer and sample allergen with a high degree of reproducibility. A clinical pilot trial proved the capability of the system to initiate symptoms in allergic subjects.

[Diagnosis of allergy in bee-keepers. A 1-year prospective study]

Thirty-six Danish bee-keepers were clinically investigated by means of a questionnaire before and after the bee season 1990. Their serum was assayed for IgE and IgG antibody reacting with bee venom, and skin prick tests were performed prior to the season. Thirty-six percent had previously reacted abnormally, either with a systemic reaction (SR) (25%) or a large local reaction (LLR) (11%). Retrospectively, eight of the nine bee-keepers with SR had upon re-exposure developed a normal reaction, in spite of the fact that seven of them had specific IgE and/or a positive prick test at subsequent examination. At follow up 38% of the persons who had previously had a SR reacted with a SR or a LLR on the first sting in the season. Two of eight with previous SR reacted with SR during the observation period in spite of a negative prick test and no specific IgE. Of the bee-keepers who had previously only reacted normally there were no systemic of large localised reactions during the observed period, although six showed signs of IgE-sensitization. The results confirm the problems of identifying patients where immunotherapy is superfluous in the group with previous SR and IgE sensitization.

Histamine-releasing serum factors as a predictor of the outcome of insect sting reactions. Results from a multicentre study

Cord blood cells were incubated (passively sensitized) with sera from 27 patients with previous systemic reactions to insect stings. Histamine release (HR) from these cells was measured following exposure to venom extracts at increasing concentrations. The aim was to see whether this parameter could predict more efficiently than RAST and skin test the outcome of a subsequent re-sting. Results showed that HR from passively sensitized cells tended to reflect skin sensitivity and specific IgE levels. If patients were not re-stung during the follow-up period, HR from the passively sensitized cells frequently decreased whereas an increase was seen (in 6/13) when using sera collected after re-sting. In conclusion HR from passively sensitized cord blood cells could not satisfactorily predict re-sting reactions in the serum donors.

Airway calibre as a confounder in interpreting bronchial responsiveness in asthma

BACKGROUND

The relation between airway responsiveness to constrictor agents and forced expiratory volume in one second (FEV1) is important when interpreting change in airway responsiveness after an intervention. The aim of the study was to analyse the relation between FEV1 as a percentage of predicted values (% predicted) and airway responsiveness between and within asthmatic subjects.

METHODS

Results of non-specific bronchial challenge tests were pooled from two randomised crossover studies comparing the effect of a non-sedative antihistamine with placebo in 35 patients with moderate asthma. The design of the two studies was similar: the provocative concentration of either histamine (first study) or methacholine (second study) resulting in a 20% decrease in ventilatory capacity (PC20) was repeated at two week intervals while patients were treated with the antihistamine or placebo. The dose of inhaled corticosteroid was gradually reduced during the study. Data were analysed with PC20 as the dependent variable in a general linear model so that the influence on PC20 of inhaled corticosteroid dose, antihistamine, and choice of bronchoconstricting agent could be separated from the influence of FEV1% predicted.

RESULTS

The correlation coefficient between mean PC20 and mean prechallenge FEV1 for each patient was 0.45. In the general linear model two thirds (65%) of the variation in PC20 was due to variation between subjects. One third of the within subject variation in PC20 could be explained by variation in prechallenge FEV1% predicted (a change in FEV1 of 27% predicted was associated with one doubling or halving of PC20). Treatment with the antihistamine had no influence on PC20, except when histamine was used as the bronchoconstricting agent. The dose of inhaled corticosteroid had a small but significant effect.

CONCLUSIONS

The variation in a patient's PC20 over time (several months) is related to changes in FEV1% predicted. Variation in FEV1% predicted explains less of the variation in bronchial responsiveness between subjects where a patient specific factor, which is probably related to the pathogenesis of bronchial asthma, seems to dominate.