Dogmas, challenges, and promises in phase III allergen immunotherapy studies.

The concept of treatment of an allergy with the offending allergen was introduced more than a century ago. Allergen immunotherapy (AIT) is the only disease modifying treatment of allergic diseases caused by inhalational allergens and insect venoms. Despite this, only few AIT products have reached licensure in the US or an official marketing authorization status in European countries. Moreover, most of these AIT products are provided on an individual patient basis as named patient products (NPP) in Europe, while individualized preparations of (mixed) allergenic extract vials for subcutaneous administration (compounding) is common practice in the US. AIT products are generally considered safe and well tolerated, but the major practical clinical development challenge is to define the optimal dose and prove the efficacy and safety of these products using state-of-the art Phase II and pivotal Phase III studies. In planning Phase II-III AIT studies, a thorough understanding of the study challenges is essential (e.g. variability and non-validated status of subjective primary endpoints, limitations of pollen season definitions) and dogmas of these products (e.g., for sublingual immunotherapy (SLIT) trials double-blinding conditions cannot be maintained, resulting in stronger placebo responses in the active treatment group and inflated treatment effects in Phase III). There is future promise for more objective biomarker endpoints (e.g. basophil activation (CD63 and CD203c), subsets of regulatory dendritic, T and B cells, IL-10-producing group 2 innate lymphoid cells; alone or in combination) to overcome several of these dogmas and challenges; innovation in AIT clinical trials can only progress with integral biomarker research to complement the traditional endpoints in Phase II-III clinical development. The aim of this paper is to provide an overview of these dogmas, challenges and recommendations based on published data, to facilitate the design of Phase III studies and improve the evidence basis of safe and effective AIT products.

Erratum to "IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper" [World Allergy Organ J 13/2 (2020) 100080].

[This corrects the article DOI: 10.1016/j.waojou.2019.100080.].

Efficacy of sublingual immunotherapy tablets in dust mite and pollen allergy.

The latest evidence on the mechanisms, efficacy, and safety of sublingual immunotherapy (SLIT) was reviewed. Interleukin (IL) 35 and IL-35-producing regulatory T cells were assessed as new biomarkers for SLIT responsiveness. A detailed analysis of clinical studies, including timothy grass pollen, 5-grass pollen, ragweed, and house-dust mite SLIT tablets, was provided, including a comparative analysis of efficacy and safety of SLIT versus subcutaneous immunotherapy.

IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper.

Currently, testing for immunoglobulin E (IgE) sensitization is the cornerstone of diagnostic evaluation in suspected allergic conditions. This review provides a thorough and updated critical appraisal of the most frequently used diagnostic tests, both in vivo and in vitro. It discusses skin tests, challenges, and serological and cellular in vitro tests, and provides an overview of indications, advantages and disadvantages of each in conditions such as respiratory, food, venom, drug, and occupational allergy. Skin prick testing remains the first line approach in most instances; the added value of serum specific IgE to whole allergen extracts or components, as well as the role of basophil activation tests, is evaluated. Unproven, non-validated, diagnostic tests are also discussed. Throughout the review, the reader must bear in mind the relevance of differentiating between sensitization and allergy; the latter entails not only allergic sensitization, but also clinically relevant symptoms triggered by the culprit allergen.

Association of the CD14 C159T and the Toll-like receptor 4 Asp299Gly polymorphisms with various phenotypes of asthma in adults from Crimea.

Background: This study assessed gene polymorphisms of the CD14 receptor (C-159T) and Toll-like receptor 4 (Asp299Gly) in a patient population in Crimea, Ukraine, stratified by clinical (early versus late onset; frequent versus occasional relapses; fixed versus reversible obstruction) and immunologic (atopic versus nonatopic; eosinophilic; neutrophilic or paucigranulocytic inflammation) subtype. Methods: Two polymorphisms, CD14 C-159T and TLR4 Asp299Gly, were assessed in 331 patients with asthma. The control group included 285 volunteers who were nonatopic. The single nucleotide polymorphisms were studied by using polymerase chain reaction with electrophoretic detection. Results: There were increased odds of asthma development in patients with the Asp299Gly TLR4 mutation compared with the general population underdominant odds ratio (OR) 1.52 [95% confidence interval (CI), 1.00-2.32] and overdominant (OR 1.55 [95% CI, 1.01-2.38]) models after adjustment for gender and age. In addition, mutations in this gene decreased the odds of nonatopic asthma in underdominant (OR 0.26 [95% CI, 0.07-0.93]; p = 0.027), overdominant (OR 0.27 [95% CI, 0.07-0.96]; p = 0.033), and log-additive models (OR 0.26 [95% CI, 0.07-0.93]; p = 0.026) compared with the atopic subgroup after adjustment for gender, age, number of exacerbations, and type of airway inflammation. Allele frequencies for CD14 and TLR4 polymorphisms did not show statistical differences between the patients with asthma and the control subjects. Conclusion: CD14 C-159T polymorphisms were not associated with asthma in the adult population in Crimea. TLR4 Asp299Gly polymorphisms were associated with asthma and with decreased odds of nonatopic asthma compared with atopic asthma in the adult population in Crimea.

In vitro impact of anti-immunoglobulin E monoclonal antibodies, including omalizumab on whole blood basophil histamine release: Assessment of direct induction of basophil histamine release and evaluation of modulation of allergen-induced basophil histamine release.

AIM: The aim of this study was to evaluate the potential of anti-immunoglobulin E (IgE) and/or anti-IgE-IgE immune complexes to release histamine from peripheral blood basophils. In addition, a potential modulating effect of anti-IgE-IgE complexes on allergen-induced peripheral blood basophil histamine release was evaluated. METHODS: Whole blood basophil histamine release (WBB-HR) tests done by using glass-fiber-based microtiter plates were performed in 62 patients with allergic rhinitis and/or asthma sensitized to perennial allergens. Evaluation of the direct effects of monoclonal anti-IgEs, including E25, E27, and QGE031, on WBB-HR, and the indirect effects of anti-IgE-serum IgE complexes on spontaneous and allergen-induced WBB-HR were conducted. The tests were performed with and without pretreatment of the basophils with interleukin 3, and the results were expressed as the fraction of total histamine content released. RESULTS: There was no difference between WBB-HR induced by any of the studied anti-IgE antibodies and that induced by isotype antibodies for all blood samples assessed, which, for each patient, was significantly less than that induced by positive anti-IgE control antibodies. Similarly, no effect of any of the studied anti-IgE-IgE complexes on spontaneous or allergen-induced WBB-HR could be demonstrated. CONCLUSION: There was no evidence that humanized, monoclonal anti-IgE antibodies E25 (omalizumab), E27, or QGE031 directly or indirectly induced histamine release from peripheral blood basophils.

Twenty-four-hour duration of effect of intranasal corticosteroids for seasonal allergic rhinitis symptoms: clinical evidence and relevance.

BACKGROUND: Seasonal allergic rhinitis (SAR) symptoms are often most severe and/or disruptive during overnight and morning hours, resulting in cognitive/performance impairments and reduced quality of life throughout the following day. Surveys of allergy patients and health care practitioners reveal a common perception that intranasal steroids (INSs), many of which are dosed q.d., fail to adequately relieve symptoms for a full 24 hours. This review assessed whether perceptions of the 24-hour duration of action of INSs correspond with duration of action documented in clinical literature. METHODS: SAR clinical trial literature of the last 5 years was reviewed to identify studies of INSs incorporating morning instantaneous (A.M. NOW) or instantaneous assessments of 24-hour duration of action. RESULTS: In numerous placebo-controlled trials of INSs in patients with SAR, treatment was associated with significantly greater improvements in A.M. NOW symptoms from baseline versus placebo. For congestion, this is noteworthy, because patients often cite this symptom, especially in the morning, as the most bothersome symptom. Comparison of A.M. NOW and daily scores suggests minimal drop in efficacy at 24 hours postdose. In several studies, INS treatment was found superior to intranasal or oral antihistamines in A.M. NOW symptom improvement. CONCLUSION: Once-daily INSs have potential for effective 24-hour symptom relief; however, there is an apparent disconnect between these findings and patient/physician perceptions. This discrepancy may be explained, in part, by less-than-ideal treatment adherence among "real-world" patients versus subjects treated in clinical trials. Proactive counseling can encourage proper INS use and help maximize treatment benefits.

Ultrashort-specific immunotherapy successfully treats seasonal allergic rhinoconjunctivitis to grass pollen.

Specific immunotherapy is a well-established treatment for allergic rhinoconjunctivitis; conventional regimens are lengthy, however, reducing convenience and cost-effectiveness. This study evaluated the efficacy and safety of an ultrashort course (four doses) of the immunotherapy Grass Modified Allergen Tyrosine Adsorbate (Allergy Therapeutics, Worthing, U.K.) monophosphoryl lipid A (MATA MPL). Subjects were randomized to receive four injections of either Grass MATA MPL (n = 514; 300-2000 standardized units/injection) or placebo (n = 514) before the grass pollen season. They used electronic diaries to record allergy symptoms and medication use during the pollen season. The primary end point was the difference between the mean combined symptom and medication scores in the Grass MATA MPL and placebo groups during the 4 local peak pollen weeks. The injection course was completed by 95.3 and 97.7% of the Grass MATA MPL and placebo groups, respectively, and was well tolerated. Grass MATA MPL treatment afforded a 13.4% benefit over placebo in the 4 peak pollen weeks (p = 0.0038). The benefit in subjects with 28 complete diary entries during the 4 peak pollen weeks was 26.9% (p = 0.0031). Significant benefits over placebo were observed in subjects with severe symptoms (17.1%; p = 0.0023), in those who had a history of allergic rhinoconjunctivitis for up to 35 years (up to 37.2%; p = 0.0059) and at sites with a higher burden of disease (38.3%; p < 0.0001). The ultrashort course of Grass MATA MPL was well tolerated and provided a significant benefit over placebo in relieving allergy symptoms.

Pharmacoeconomics of levocetirizine in allergic rhinitis and chronic idiopathic urticaria: considerations for the USA.

BACKGROUND: Levocetirizine, a recent, second-generation oral antihistamine, was approved by the US FDA in May 2007 to treat symptoms of allergic rhinitis and chronic idiopathic urticaria. OBJECTIVE: To review the economic literature for levocetirizine. METHODS: Two reviewers conducted a systematic review of the literature to identify abstracts that met the inclusion criteria. Abstracts that were considered acceptable were retrieved with full text for further assessment. RESULTS: A total of 82 potential studies were identified. After reviewing abstracts, 11 articles were preselected for potential inclusion. Of the 11 full-text articles, three articles met the inclusion criteria. CONCLUSION: The pharmacoeconomic literature for levocetirizine was limited. The findings were consistent across the literature, suggesting levocetirizine improved outcomes, leading to incremental cost savings and cost-effectiveness. Since many of the available levocetirizine data come from European studies, differences in practice patterns and medical resources should be considered when extrapolating data to a US clinical setting.

Evaluation of a simple, potentially individual device for exhaled breath temperature measurement.

RATIONALE: Inflammation is a universal pathological reaction and is characterized among other things by increased heat production. The question stays whether the contribution of the inflamed lung tissues to the overall exhaled breath temperature (EBT) can be reliably detected and used in everyday clinical practice. METHODS: We have designed a simple device for assessment of EBT and explored its performance under standard indoor conditions. We made our measurements in the morning hours, documenting the ambient conditions (room temperature, humidity, atmospheric pressure), and physiological characteristics of the tested subjects (heart rate, blood pressure, otic and axillary temperature). We assessed its day-to-day reproducibility in 17 healthy volunteers and its ability to discriminate between the same subjects without respiratory disease and uncontrolled asthmatics (n=14). We also compared the EBT of the 14 asthmatics before and after anti-inflammatory treatment. RESULTS: No association was found between EBT and any of the ambient conditions: room temperature, atmospheric pressure and humidity. While otic and axillary temperatures, which were measured in parallel, maintained high correlation between each other (Spearman's rho=0.71, p<0.01), EBT did not show meaningful association with any of them. The EBT (degrees C) of asthmatics (median 35.45, range 34.12-36.09) was higher than that of controls (34.84, 32.29-35.84), (p=0.009, Mann-Whitney U test). Anti-inflammatory treatment brought down the EBT of the asthmatics (34.78, 33.23-36.06), (p=0.001, Wilcoxon Signed Ranks test), while significantly improving their spirometry too. CONCLUSIONS: Measurements of EBT with the device we constructed are not significantly influenced by changes within the accepted range of a standard indoor environment. EBT represents a different characteristic of the human organism than otic and axillary temperatures. EBT is increased in uncontrolled asthmatics and decreases under anti-inflammatory treatment.

Levocetirizine: The latest treatment option for allergic rhinitis and chronic idiopathic urticaria.

Levocetirizine is the most recent antihistamine available in the United States and is indicated for the symptomatic treatment of allergic rhinitis (AR; seasonal [SAR] and perennial [PAR]) and chronic idiopathic urticaria (CIU). The purpose of this study was to review the current literature on pharmacologic properties of levocetirizine, its safety, tolerability, and effectiveness in AR and CIU. Relevant articles in English or with English abstracts were identified from systematic Medline searches using combinations of the terms antihistamine/s, CIU, H(1)-receptor antagonist/s, levocetirizine, PAR and persistent AR (PER), pharmacodynamic, pharmacokinetic, and SAR. Levocetirizine is the active enantiomer of cetirizine. Pharmacologic and clinical studies indicate that levocetirizine has a fast onset and long duration of action, with a well-tolerated adverse effect profile. These favorable features may be caused by levocetirizine's pharmacokinetic and pharmacodynamic properties including high bioavailability, low apparent volume of distribution, low degree of metabolism, and high in vivo potency and H(1)-receptor occupancy. Several large well-controlled clinical trials in adults and children aged 6-12 years have shown levocetirizine to be consistently efficacious and well tolerated in relieving the symptoms of SAR, PAR, and PER and CIU. Levocetirizine is a welcome new treatment option in the United States for symptomatic treatment of AR and CIU.

Montelukast with desloratadine or levocetirizine for the treatment of persistent allergic rhinitis.

BACKGROUND: Montelukast sodium is approved as a treatment for intermittent and persistent allergic rhinitis (AR), but it has not been evaluated as combined therapy with antihistamines for persistent AR. OBJECTIVE: To investigate the effects of 6 weeks of treatment of persistent AR with desloratadine, levocetirizine, or montelukast alone or in combination. METHODS: A randomized, double-blind, placebo-controlled crossover study was performed. Patients were assigned to 2 arms: 20 received montelukast, 10 mg/d, desloratadine, 5 mg/d, or both or placebo and 20 received montelukast, levocetirizine, or both, 5 mg/d, or placebo. The treatment periods were separated by 2-week washout periods. Symptom scoring, skin prick tests, spirometry, rhinometry, and nasal lavage were performed the day before and the last days of the treatment periods. Eosinophil cationic protein levels were evaluated by means of nasal lavage. RESULTS: The mean +/- SD total baseline nasal symptom score was 7.7 +/- 0.49 before treatment, 3.74 +/- 0.54 after desloratadine use, 3.6 +/- 0.48 after montelukast use, and 3.04 +/- 0.4 after montelukast-desloratadine use. The mean +/- SD baseline nasal symptom score was 7.95 +/- 0.68 before treatment, 3.02 +/- 0.64 after levocetirizine use, 3.44 +/- 0.55 after montelukast use, and 2.14 +/- 0.39 after montelukast-levocetirizine use. The greatest improvement in nasal symptoms occurred after combination treatment. Decreases in the level of eosinophil cationic protein were greater after the combined use of montelukast and antihistamine than after each agent given alone. CONCLUSIONS: For persistent AR, the combination of montelukast and either desloratadine or levocetirizine is more effective than monotherapy with these agents.

Review of desloratadine for the treatment of allergic rhinitis, chronic idiopathic urticaria and allergic inflammatory disorders.

Desloratadine is a once-daily, non-sedating, non-impairing, selective histamine H1-receptor antagonist. It relieves the symptoms of seasonal allergic rhinitis (including nasal obstruction and congestion, and morning symptoms), perennial allergic rhinitis and chronic idiopathic urticaria by blocking multiple critical steps in the systemic allergic cascade and downregulating key allergy-induced inflammatory mediators. It also relieves asthma symptoms and decreases rescue medication use in patients with seasonal allergic rhinitis and comorbid asthma. Numerous clinical studies have demonstrated that desloratadine is safe, well tolerated and free of serious cardiac effects. Pharmacokinetic studies have demonstrated a low propensity for drug-drug or drug-food interactions. This review outlines the mechanism of action, efficacy and safety of desloratadine for the treatment of allergic inflammatory disorders.

The role of P-glycoprotein and organic anion-transporting polypeptides in drug interactions.

The use of polytherapy in clinical practice necessitates an appreciation and understanding of the potential for drug interactions. Recent publications provide insight into the role of the active transport systems P-glycoprotein (P-gp) and human organic anion-transporting polypeptides (OATPs) in drug interactions. Active drug transporters influence the bioavailability of a number of drugs by controlling their movement into, and out of, cells. The active transport systems P-gp and OATP play an important role in drug elimination. The activity of these transport systems is controlled, in part, by genetic factors; however, drugs and foods also influence the activity of these systems. It appears that interference with P-gp or OATP, either as upregulation or inhibition, may affect plasma drug concentrations by altering intestinal absorption, proximal renal-tubular excretion or biliary excretion. Overall, the net bioavailability of a drug or substance is affected by the relative contributions of cellular efflux (P-gp) and influx (OATP) mechanisms and to what extent these systems are active during phases of uptake and absorption versus removal and excretion from the body. Many of the drugs and foods that affect active drug transport activity are known to interact with the cytochrome P450 enzyme system; therefore, the net effect of concomitant drug administration is complex. One must now consider the impact of metabolism (CYP-mediated drug biotransformation), P-gp-mediated drug efflux and OATP-mediated uptake when making assessments of drug absorption and distribution.

Effect of allergen-specific immunotherapy on recombinant human interleukin 3-mediated amplification of allergen-induced basophil histamine release.

Decreased allergen-induced histamine release from peripheral blood basophils in allergic rhinitis patients treated with specific immunotherapy (SIT) correlates with clinical outcomes of SIT. The aim of this study was to investigate if decreased histamine release is a permanent effect of SIT. Fifty-one patients (mean age, 35.3 years) with allergic rhinitis, diagnosed based on clinical history and positive skin-prick test results to common aeroallergens, were studied. Twenty-three patients had never received SIT (group A), and 28 patients had been treated with inhalant allergen extracts (group B). Eleven patients from group A participated in a prospective part of this study. Basophil histamine release in these patients was evaluated before (TO) and after-1 year (TI) of SIT. Histamine release from peripheral blood with and without interleukin (IL)-3 pretreatment was performed using the glass-fiber-based histamine release test. Brief pretreatment of whole blood basophils with one of the four concentrations (0.01, 0.1, 1, or 10 ng/mL) of recombinant human IL(rhIL)-3, rhIL-5, or rh-granulocyte-macrophage colony-stimulating factor resulted in a significant amplification of allergen-induced basophil histamine release. The amplification using cytokines at the optimal concentrations was the greatest with rhIL-3 and the lowest with rhIL-5; therefore, for further studies rhIL-3 was used. Prospective analysis showed no significant difference in allergen-induced basophil histamine release on rhIL-3 pretreatment after 1 year of SIT (192.7 +/- 75.3 ng and 176.1 +/- 76.4 ng for T0 and T1, respectively; p = 0.18). Short-term SIT does not decrease rhIL-3-mediated amplification of allergen-induced histamine release from peripheral blood basophils.

In vitro diagnostic evaluation of patients with inhalant allergies: summary of probability outcomes comparing results of CLA- and CAP-specific immunoglobulin E test systems.

For the diagnosis of allergy, presence of allergen-specific immunoglobulin E (IgE) usually is established either by allergen skin tests or by in vitro allergen-specific IgE measurements. However, in vitro assays of specific IgE often are modified as manufacturers improve allergens or change reagents to optimize test performance, affecting the diagnostic performance of in vitro allergen-specific IgE assays. This investigation compares the diagnostic outcomes of the Hitachi Chemical Diagnostics chemiluminescent assay (CLA) and Pharmacia, capsulated hydrophilic carrier polymer (CAP) in vitro allergen-specific IgE test methods in patients with inhalant allergy to a panel of selected allergens. Sera were obtained from 60 consecutive patients who had a clinical history suggesting inhalant allergy and were evaluated by allergen skin-prick test (SPT). Only patients with clinical findings of allergic asthma or rhinoconjunctivitis were included. Sera from patients with at least one positive SPT, which clinically correlated with the case history, were used for specific IgE measurements. Sensitivity and specificity were defined as conditional probabilities describing performances of the CAP system and the CLA system in reference to a standard composed of a combination of allergen-specific symptoms and a positive SPT. A test concordance of 79% was found between the CLA and CAP test results with a correlation coefficient of 0.8. Allergen-specific IgE assay sensitivity of the CLA and CAP systems was similar and allergen dependent, ranging from 67 to 100%. Assay specificity ranged from 39 to 86% for the CLA system and from 36 to 81% for the CAP system. When comparing the specific IgE results with allergen SPTs, 75% (+/- 3%) of CLApositive patients had a positive SPT, and 92% (+/- 4%) of CAPpositive patients had a positive SPT. Eighty-four percent (+/- 4%) of CLAnegative patients had a negative SPT, whereas 69% (+/- 5%) of CAPnegative patients had a negative SPT. The overall concordance between skin tests and in vitro tests was 76% for CLA and 67% for CAP. CLA and CAP score values showed good correlation and both tests may be useful when skin tests cannot be performed to identify subjects with IgE-mediated allergy. The CLA and CAP assays for allergen-specific IgE may be useful as part of an initial allergy evaluation because of the high negative predictive value of negative test results. For the majority of allergens the sensitivity was high. However, the specificity of both in vitro tests was low, indicating that positive in vitro test results should be evaluated carefully in conjunction with clinical symptoms and allergen-specific skin tests to determine the clinical relevance of the allergen sensitization.

Structural and functional properties of IL-4delta2, an alternative splice variant of human IL-4.

Structural and functional properties of recombinant IL-4delta2, a naturally occurring splice variant of human IL-4 with a deletion of the loop region 22-37, have been analyzed. IL-4delta2 has alpha-helical structure and most likely preserves the "up-up-down-down" topology typical of the four-helix-bundle cytokines. IL-4delta2 interacts specifically with the alpha chain of IL-4R and competes effectively with IL-4 for the common binding sites. Thus, IL-4delta2 may act as a regulator of the cytokine net, being the natural antagonist of IL-4.

Comparative effects of desloratadine versus montelukast on asthma symptoms and use of beta 2-agonists in patients with seasonal allergic rhinitis and asthma.

BACKGROUND: Asthma and seasonal allergic rhinitis (SAR) are recognized as manifestations of a single airway disease. Desloratadine has demonstrated efficacy in treating SAR symptoms, including nasal obstruction. METHODS: Safety and efficacy of desloratadine and montelukast each were assessed in a double-blind, placebo-controlled trial of patients with SAR and symptoms of asthma, who were assigned randomly to once-daily treatment with desloratadine 5 mg, montelukast 10 mg, or placebo for 4 weeks. Change from baseline of AM/PM reflective total asthma symptom severity scores (TASS), FEV(1), individual asthma symptom scores, and beta(2)-agonist usage were assessed. RESULTS: Desloratadine and montelukast each were associated with statistically significant reductions from baseline in the mean TASS averaged over the 4-week period (p < or =0.022 vs. placebo). Individual asthma symptom scores also improved significantly for both therapies (p < or = 0.05). Patients treated with desloratadine or montelukast demonstrated improvement from baseline in FEV(1) versus placebo; significant improvement was seen in a subset of patients with baseline FEV(1) <80% of predicted normal (both p < 0.05). Both active therapies significantly reduced beta(2)-agonist use (both p < 0.01). Improvements for both therapies were comparable for all efficacy parameters; they were tolerated well with adverse event profiles similar to placebo. CONCLUSIONS: Asthma symptoms and beta(2)-agonist were improved significantly in patients with concomitant SAR and asthma treated with desloratadine 5 mg as well as montelukast 10 mg once daily. Both therapies significantly improved FEV(1) in a subset of patients with FEV(1) <80% of predicted normal at entry. Improvements in asthma symptoms were comparable for both active treatment groups.

Prevalence of allergen-specific IgE among patients with chronic fatigue syndrome.

The prevalence of atopy among patients having chronic fatigue syndrome (CFS) has been reported to be as high as 80% in published surveys of patients with this syndrome. However, many of the reports relied on self-assessment by patients for the presence of atopy or solely used total immunoglobulin E (IgE) levels to assess the likelihood of atopy. To more critically assess the presence of atopy among patients with CFS, testing was done for total IgE and allergen-specific IgE using the Pharmacia CAP system including 20 common allergens: trees (birch/oak/ash), grass (rye/blue), weeds (common/giant ragweed), molds (Penicillium/Aspergillus/Alternaria), dust mites (Dermatophagoides pteronyssinus/Dermatophagoides farinae), animal dander (cat/dog), and foods (egg white/milk/wheat/corn/peanut/shrimp). Testing of 50 patients having documented CFS indicated that 78% had total IgE < 100 IU/mL, among whom 26% had a positive test for allergen-specific IgE of class I or greater for one or more allergens. Among the 22% of CFS patients having a total IgE > 100 IU/mL, 73% had a positive test for allergen-specific IgE for one or more allergens. The most commonly positive allergens were dust mites (24-26%), whereas molds (0-6%) and foods (0-4%) were rarely positive. The overall frequency of positive results for the presence of allergen-specific IgE among CFS patients was 36%, not significantly different from the normal prevalence of these antibodies in the general population (20-35%). This assessment of the prevalence of allergen-specific IgE antibodies in patients with CFS fails to support a potential association between CFS and atopy.