Allergen-specific IgE measured by a continuous random-access immunoanalyzer: interassay comparison and agreement with skin testing

Performance of EAST in diagnosing inhalant allergens in children with allergic rhinitis

The performance of enzyme linked immunosorbent assays (EAST) for identifying six indoor allergens was evaluated using skin prick test (SPT) as reference tests in 154 children with allergic rhinitis. Sensitivity of EAST ranged from 9% (cat) to 54% (HDM) with specificity of 74%(cockroach) to 100% (cat) with an agreement ranged from 58 to 86%. Cut off values ​> ​0.35 kU/L showed best sensitivity and specificity. Our findings agree with extant literature which suggests that the ability of EAST to determine the precipitating allergen is moderate. Assays for definitively identifying the inhalant allergen are currently not available.

Pollen Allergy Screening with Allergen-Specific and Total Immunoglobulin E Titers

Background

Allergic rhinitis is a typical type I hypersensitivity reaction, commonly caused by inhalant allergens. Accurate identification of the causative antigen is important for rapid diagnosis and treatment initiation.

Objective

This study examined the efficiency of serum-based allergen-specific immunoglobulin E and total immunoglobulin E antibody titers in screening for pollen allergy. We also examined the effect of cross-reactive carbohydrate determinants on specific immunoglobulin E titers in screening for pollen allergy, one of the causes of false positivity in specific immunoglobulin E measurements.

Methods

A questionnaire was used to evaluate the symptoms of pollinosis among participants who underwent a medical examination. One hundred and thirty-two participants reported pollen allergy symptoms and 127 reported an absence of symptoms. Specific immunoglobulin E levels were measured using the AlaSTAT 3g Allergy method. Seventeen components, including four types of cross-reactive carbohydrate determinant-specific immunoglobulin E antibodies, were measured and evaluated comparatively.

Results

The sensitivity and specificity of the tests in predicting the presence or absence of pollen allergy were analyzed. The values of the areas under the curves for immunoglobulin E antibody levels against cedar, cypress, orchard grass, and ragweed pollen were 0.87, 0.82, 0.63, and 0.56, respectively. A cross-reactive carbohydrate determinant-related false-positive effect on the pollen specific immunoglobulin E titer was noted in pollen screening.

Conclusion

Cedar pollen-specific immunoglobulin E titers showed sufficient accuracy for use in pollen allergy screening. The study of cross-reactive carbohydrate determinants suggested that subjects who tested positive for pollen often had false-positive results due to the impact of cross-reactive carbohydrate determinants.

Evaluation of a fully automated and completely quantitative allergen-specific IgE and total IgE detection assay

Based on the current urgent need for an in vitro quantitative detection system for allergens in most hospitals in China, we introduced a novel allergen-specific immunoglobulin E detection system that employs a solid phase enzyme-linked immunoassay and evaluated its clinical performance. The system uses a special reaction component (innovative patents) to reduce the reaction time to 12 min, achieving point-of-care testing for allergy management, which is impressive compared to the 3-18 h testing time for all other systems. In addition, the AILEX system has excellent consistency with the ImmunoCAP reference method system; therefore, we recommend the introduction of the AILEX system for clinical auxiliary diagnosis in medical units.

Precision Medicine in Hymenoptera Venom Allergy: Diagnostics, Biomarkers, and Therapy of Different Endotypes and Phenotypes

Allergic reactions to stings of Hymenoptera species may be severe and are potentially fatal deviations of the immunological response observed in healthy individuals. However, venom-specific immunotherapy (VIT) is an immunomodulatory approach able to cure venom allergy in the majority of affected patients. An appropriate therapeutic intervention and the efficacy of VIT not only depend on a conclusive diagnosis, but might also be influenced by the patient-specific manifestation of the disease. As with other diseases, it should be borne in mind that there are different endotypes and phenotypes of venom allergy, each of which require a patient-tailored disease management and treatment scheme. Reviewed here are different endotypes of sting reactions such as IgE-mediated allergy, asymptomatic sensitization or a simultaneous presence of venom allergy and mast cell disorders including particular considerations for diagnosis and therapy. Additionally, phenotypical manifestations of venom allergy, as e.g. differences in age of onset and disease severity, multiple sensitization or patients unsusceptible to therapy, are described. Moreover, biomarkers and diagnostic strategies that might reflect the immunological status of the patient and their value for therapeutic guidance are discussed. Taken together, the increasing knowledge of different disease manifestations in venom hypersensitivity and the growing availability of diagnostic tools open new options for the classification of venom allergy and, hence, for personalized medical approaches and precision medicine in Hymenoptera venom allergy.

The role of component-resolved diagnosis in Hymenoptera venom allergy

PURPOSE OF REVIEW

Component-resolved diagnostics (CRD) is a new tool aiming at detecting IgE-mediated sensitizations against individual, relevant allergens. Here, we discuss recent literature on molecular diagnosis in the field of Hymenoptera venom allergy (HVA) as well as CRD strengths and weaknesses.

RECENT FINDINGS

CRD, using single molecules or panels of allergens, may discriminate between primary sensitization and cross-reactivity in patients with double/multiple positivity in diagnostic tests with whole extracts, allowing the specialist to choose the most suitable venom for specific immunotherapy (VIT), avoiding unnecessary VIT and reducing the risk of side effects. Future availability of the cross-reactive recombinant pairs of allergens of different species may further increase the diagnostic performance. CRD may be useful in patients with negative allergy tests and a proven history of a previous systemic reaction, including those with mast cell disorders, who could benefit from VIT. In honeybee venom allergy, different sensitization profiles have been identified, which could be associated with a greater risk of VIT failure or treatment side effects.

SUMMARY

CRD is undoubtedly an innovative diagnostic method that leads to a more precise definition of the sensitization profile of the HVA patient. Together with a better knowledge of the molecular composition of different venom extracts, CRD may contribute to optimize patient-tailored therapy.

Antigen 5 Allergens of Hymenoptera Venoms and Their Role in Diagnosis and Therapy of Venom Allergy

PURPOSE OF REVIEW

Stings of Hymenoptera of the superfamily Vespoidea such as yellow jackets, paper wasps or stinging ants are common triggers for severe and even fatal allergic reactions. Antigen 5 allergens are potent allergens in the majority of these venoms with major importance for diagnosis and therapy. Reviewed here are the characteristics of antigen 5 allergens, their role in component-resolved diagnostics as well as current limitations of the available diagnostics for proper therapeutic decisions.

RECENT FINDINGS

Antigens 5 are proteins of unknown function in Hymenoptera venoms with high allergenic potency. They represent key elements in component-resolved diagnosis to discriminate between honeybee and vespid venom allergy. However, due to their pronounced cross-reactivity, there are remaining diagnostic and therapeutic challenges that have to be addressed. Antigens 5 are highly relevant venom allergens of the Vespoidea superfamily. Although their use in component-resolved diagnosis facilitates dissection of cross-reactivity and primary allergy in double sensitization to honeybee and vespid venom, new diagnostic concepts are needed to discriminate between allergies to different vespid species.

Evaluation of AdvanSure AlloScreen Max Panel With 92 Different Allergens for Detecting Allergen-Specific IgE

OBJECTIVES

The objective of this study was to examine the performance of AdvanSure AlloScreen Max with 92 different allergens compared to Polycheck Allergy and ImmunoCAP. The relationship of serum IgE concentration with the number and the highest class/level of positive allergen-specific IgEs was also examined.

METHODS

A total of 406 serum samples were included in this study. Discrepant cases between AdvanSure AlloScreen Max and Polycheck Allergy underwent ImmunoCAP testing for allergen-specific IgE.

RESULTS

Total agreement of the two multiple allergen simultaneous tests (MAST) was 92.5%. Compared to ImmunoCAP, total agreement rate was higher with AdvanSure AlloScreen Max (60.8%) than that with Polycheck Allergy (39.2%). Serum IgE concentration showed a significant and positive correlation with the number and the highest class/level of positive allergen-specific IgEs.

CONCLUSIONS

A MAST assay panel containing as many allergens as possible would be more helpful in the allergen screening for patients with high serum IgE concentration.

Precision medicine allergy immunoassay methods for assessing immunoglobulin E sensitization to aeroallergen molecules

Molecular-based allergy diagnosis for the in vitro assessment of a patient immunoglobulin E (IgE) sensitization profile at the molecular level uses allergen molecules (also referred to as allergen components), which may be well-defined, highly purified, natural allergen components or recombinant allergens. Modern immunoassay methods used for the detection of specific IgE against aeroallergen components are either singleplex (such as the fluorescence enzyme immunoassay with capsulated cellulose polymer solid-phase coupled allergens, the enzyme-enhanced chemiluminescence immunoassay and the reversed enzyme allergosorbent test, with liquid-phase allergens), multiparameter (such as the line blot immunoassay for defined partial allergen diagnostics with allergen components coating membrane strips) or multiplex (such as the microarray-based immunoassay on immuno solid-phase allergen chip, and the two new multiplex nanotechnology-based immunoassays: the patient-friendly allergen nano-bead array, and the macroarray nanotechnology-based immunoassay used as a molecular allergy explorer). The precision medicine diagnostic work-up may be organized as an integrated “U-shape” approach, with a “top-down” approach (from symptoms to molecules) and a “bottom-up” approach (from molecules to clinical implications), as needed in selected patients. The comprehensive and accurate IgE sensitization molecular profiling, with identification of the relevant allergens, is indicated within the framework of a detailed patient’s clinical history to distinguish genuine IgE sensitization from sensitization due to cross-reactivity (especially in polysensitized patients), to assess unclear symptoms and unsatisfactory response to treatment, to reveal unexpected sensitizations, and to improve assessment of severity and risk aspects in some patients. Practical approaches, such as anamnesis molecular thinking, laboratory molecular thinking and postmolecular anamnesis, are sometimes applied. The component-resolved diagnosis of the specific IgE repertoire has a key impact on optimal decisions making for prophylactic and specific immunotherapeutic strategies tailored for the individual patient.

Component-resolved diagnostics to direct in venom immunotherapy: Important steps towards precision medicine

Stings of Hymenoptera can induce IgE-mediated systemic and even fatal allergic reactions. Venom-specific immunotherapy (VIT) is the only disease-modifying and curative treatment of venom allergy. However, choosing the correct venom for VIT represents a necessary prerequisite for efficient protection against further anaphylactic sting reactions after VIT. In the past, therapeutic decisions based on the measurement of specific IgE (sIgE) levels to whole venom extracts were not always straightforward, especially when the patient was not able to identify the culprit insect. In the last years, the increasing knowledge about the molecular structure and relevance of important venom allergens and their availability as recombinant allergens, devoid of cross-reactive carbohydrate determinants, resulted in the development of an advanced component-resolved diagnostics (CRD) approach in venom allergy. Already to date, CRD has increased the sensitivity of sIgE detection and enabled the discrimination between primary sensitization and cross-reactivity, particularly in patients with sensitization to both honeybee and vespid venom. Hence, CRD in many patients improves the selection of the appropriate immunotherapeutic intervention. Moreover, the detailed knowledge about sensitization profiles on a molecular level might open new options to identify patients who are at increased risk of side-effects or not to respond to immunotherapy. Therefore, increasing potential of CRD becomes evident, to direct therapeutic decisions in a personalized and patient-tailored manner. Reviewed here are the state of the art options, recent developments and future perspectives of CRD of Hymenoptera venom allergy.

Aspergillus fumigatus in cystic fibrosis: An update on immune interactions and molecular diagnostics in allergic bronchopulmonary aspergillosis

A wide spectrum of pathological conditions may result from the interaction of Aspergillus fumigatus and the immune system of its human host. Allergic bronchopulmonary aspergillosis is one of the most severe A. fumigatus-related diseases due to possible evolution toward pleuropulmonary fibrosis and respiratory failure. Allergic bronchopulmonary aspergillosis occurs almost exclusively in cystic fibrosis or asthmatic patients. An estimated 8%-10% of patients with cystic fibrosis experience this condition. The diagnosis of allergic bronchopulmonary aspergillosis relies on criteria first established in 1977. Progress in the understanding of host-pathogen interactions in A. fumigatus and patients with cystic fibrosis and the ongoing validation of novel laboratory tools concur to update and improve the diagnosis of allergic bronchopulmonary aspergillosis.

Comparison between skin prick test and serum immunoglobulin E by CAP system to inhalant allergens

BACKGROUND

Skin prick tests (SPTs) and measurements of serum specific immunoglobulin E (sIgE) antibodies are the most commonly used diagnostic tools for confirming sensitization. However, disagreement between the tests has been observed.

OBJECTIVE

To compare SPT and the CAP system for diagnosis of sensitization to common inhalant allergens.

METHODS

Subjects included 2,635 patients 10 to 90 years old who underwent analyses by SPT and CAP at the Dong-A University Hospital (Busan, Korea) from June 2011 through May 2016. The 2 test results were compared for 17 inhalant allergens.

RESULTS

Agreement between the SPT and sIgE level was 75.3%. Overall agreement was moderate (κ = 0.59), with strong agreement for house dust mites and birch (κ > 0.7) and weak agreement for Tyrophagus putrescentiae and dog (κ < 0.3). When CAP was compared with SPT as the reference, the sensitivity was 75.8% and the specificity was 75.2%. Mean wheal size by SPT showed a positive correlation with sIgE levels (r = 0.59), which decreased with age.

CONCLUSION

There was a discrepancy between SPT and CAP for diagnosing allergic sensitization among inhalant allergens. The allergic sensitization and correlation between the tests decreased with age. Cautious interpretation of the clinical relevance of allergen sensitization based on SPT and CAP results is required, especially in older patients.

ImmunoCAP cellulose displays cross-reactive carbohydrate determinant (CCD) epitopes and can cause false-positive test results in patients with high anti-CCD IgE antibody levels

BACKGROUND

Cross-reactive carbohydrate determinants (CCDs) in plants and insect venoms are a common cause of irrelevant positive test results during in vitro allergy diagnosis. We observed that some CCD-positive sera show nonspecific IgE binding even with CCD-free recombinant allergens when using the Phadia ImmunoCAP platform.

OBJECTIVE

We investigated whether cellulose used as an allergen carrier in ImmunoCAP harbors residual N-glycans, causing nonspecific background binding in CCD-positive sera.

METHODS

IgE binding to 6 samples of blank ImmunoCAPs coupled to either streptavidin (SA-CAP-1 or 2) or nonallergenic maltose-binding protein (MBP; MBP-CAP-1 to 4) and binding to a panel of 4 recombinant allergens were compared in CCD-positive sera before and after inhibition with a CCD inhibitor (MUXF³-human serum albumin).

RESULTS

Of 52 CCD-positive sera (bromelain, 1.01-59.6 kilounits of antigen per liter [kU_A/L]) tested on SA-CAP-1, 35 (67%) showed IgE binding of greater than 0.35 kU_A/L (0.41-4.22 kU_A/L). Among those with anti-CCD IgE levels of greater than 7.0 kU_A/L, 90% (26/29) were positive. IgE binding to SA-CAP-1 correlated with IgE binding to bromelain (r = 0.68) and was completely abolished by serum preincubation with the CCD inhibitor (n = 15). Binding scores with SA-CAP-2 and MBP-CAP-1 to MBP-CAP-4 were generally lower but strongly correlated with those of SA-CAP-1 and bromelain. IgE reactivity of 10 CCD-positive sera (14.0-52.5 kU_A/L) with the recombinant allergens rPhl p 12, rFel d 1, rAra h 2, and rPru p 3 was positive to at least 1 allergen in 8 of 10 (0.36-1.63 kU_A/L) and borderline in 2 of 10 (0.21-0.25 kU_A/L). Binding correlated with antibody binding to bromelain (r = 0.61) and to all blank ImmunoCAPs (r > 0.90) and could be completely blocked by the CCD inhibitor. Overall, mean background binding to cellulose CCDs corresponded to 2% to 3% of the reactivity seen with bromelain.

CONCLUSIONS

Cellulose used as a solid-phase allergen carrier can contain varying amounts of CCDs sufficient to cause false-positive test results up to 2 kU_A/L with nonglycosylated recombinant allergens in patients with high levels of anti-CCD IgE antibodies.

Six years of INSTAND e. V. sIgE proficiency testing: An evaluation of in vitro allergy diagnostics

Background

Even though allergies are an important health issue, wide manufacturer-dependent differences in the detected amounts of allergen-specific IgE (sIgE) have repeatedly been found. These discrepancies hinder diagnostics and research into clinically significant cutoff points for life-threatening symptoms.

Methods

To evaluate whether the reported differences have led to changes in diagnostic testing, we analyzed data from six years of round robin testing (RRT, also known as proficiency testing) at the Gesellschaft zur Förderung der Qualitätssicherung in medizinischen Laboratorien e.V.  (Society for Promoting Quality Assurance in medical Laboratories) for the important allergen sources bee venom, wasp venom, and birch pollen. The results of the four main suppliers of in vitro diagnostic sIgE testing were compared in a pseudo-anonymized form using overlay images of box plot graphs for the semiquantitative data and allergen class results. Coefficients of variation (CV) were obtained to study the development of interlaboratory comparability.

Results

We found that the large differences between the manufacturer collectives remained constant between January 2010 and April 2015 without any real improvement. The CVs were good for two of the four analyzed suppliers, one was marginal and one above the quality level of 20%.

Conclusion

The numerous publications that have found discrepancies in the sIgE results of the different suppliers did not change the status quo within the last six years. Unfortunately, this is unlikely to change until there is a characterized standard material with known values of sIgE.

Application of recombinant antigen 5 allergens from seven allergy-relevant Hymenoptera species in diagnostics

BACKGROUND

Hymenoptera stings can cause severe anaphylaxis in untreated venom-allergic patients. A correct diagnosis regarding the relevant species for immunotherapy is often hampered by clinically irrelevant cross-reactivity. In vespid venom allergy, cross-reactivity between venoms of different species can be a diagnostic challenge. To address immunological IgE cross-reactivity on molecular level, seven recombinant antigens 5 of the most important Vespoidea groups were assessed by different diagnostic setups.

METHODS

The antigens 5 of yellow jackets, hornets, European and American paper wasps, fire ants, white-faced hornets, and Polybia wasps were recombinantly produced in insect cells, immunologically and structurally characterized, and their sIgE reactivity assessed by ImmunoCAP, ELISA, cross-inhibition, and basophil activation test (BAT) in patients with yellow jacket or Polistes venom allergy of two European geographical areas.

RESULTS

All recombinant allergens were correctly folded and structural models and patient reactivity profiles suggested the presence of conserved and unique B-cell epitopes. All antigens 5 showed extensive cross-reactivity in sIgE analyses, inhibition assays, and BAT. This cross-reactivity was more pronounced in ImmunoCAP measurements with venom extracts than in sIgE analyses with recombinant antigens 5. Dose-response curves with the allergens in BAT allowed a differentiated individual dissection of relevant sensitization.

CONCLUSIONS

Due to extensive cross-reactivity in various diagnostic settings, antigens 5 are inappropriate markers for differential sIgE diagnostics in vespid venom allergy. However, the newly available antigens 5 from further vespid species and the combination of recombinant allergen-based sIgE measurements with BAT represents a practicable way to diagnose clinically relevant sensitization in vespid venom allergy.

Staphylococcus aureus enterotoxin sensitization involvement and its association with the CysLTR1 variant in different asthma phenotypes

BACKGROUND

Sensitization to Staphylococcus aureus enterotoxin (SE) is a known risk factor for asthma susceptibility and severity. However, how SE sensitization is involved in asthma, particularly nonatopic asthma and/or late-onset asthma, remains uncertain.

OBJECTIVE

To clarify the involvement of SE sensitization in nonatopic and/or late-onset asthma and its association with a polymorphism of the cysteinyl leukotriene receptor 1 gene (CysLTR1), which was examined because CysLT signaling is closely associated with late-onset eosinophilic asthma.

METHODS

We assessed associations between sensitization to SE (A and/or B) and clinical indexes in 224 patients with asthma (mean age, 62.3 years; 171 women) from a cohort of the Kinki Hokuriku Airway Disease Conference, particularly those with nonatopic asthma (not sensitized to common aeroallergens) and/or late-onset asthma. Associations between SE sensitization and CysLTR1 polymorphism (rs2806489), a potential regulatory variant for atopic predisposition in women, were also assessed in a sex-stratified manner.

RESULTS

A total of 105 patients (47%) with asthma were sensitized to SE. Among patients with nonatopic asthma (n = 67) or with late-onset asthma (n = 124), those sensitized to SE had significantly higher serum total IgE and periostin levels than those not sensitized. In nonatopic patients, a rapid decrease in forced expiratory volume in 1 second was associated with SE sensitization. In women with asthma, rs2806489 was associated with sensitization to SEB and age at asthma onset.

CONCLUSION

SE sensitization contributes to T_H2 inflammation in nonatopic and/or late-onset asthma. In women with asthma, the CysLTR1 variant might be associated with sensitization to SEB and age at asthma onset.

Food Allergy in Korean Patients with Chronic Urticaria

Background

The etiology of chronic urticaria (CU) remains unknown in most patients. Possible causes in some cases include food, but the role of allergy to food antigens in patients with CU remains controversial.

Objective

The aim of this study was to evaluate the association between food allergy and CU.

Methods

Korean patients with CU were assessed for a previous history of food allergy that caused symptoms of CU. Blood samples were taken from 350 patients to measure food allergen-specific IgE. Based on history and laboratory results, open oral food challenge (OFC) tests were performed.

Results

Of 350 participants, 46 (13.1%) claimed to have experienced previous food hypersensitivity. Pork (n=16) was the main food mentioned, followed by beef (n=7), shrimp (n=6), and mackerel (n=6). We found that 73 participants (20.9%) had elevated levels of food-specific IgE, with pork (n=30), wheat (n=25), and beef (n=23) being the most common. However, when the open OFC tests were conducted in 102 participants with self-reported food hypersensitivity or raised levels of food-specific IgE, only four participants showed a positive reaction to pork (n=3) or crab (n=1).

Conclusion

Although some participants claimed to have a history of CU related to food intake, when an open OFC test was conducted, few of them had positive results. We therefore conclude that food allergy is an uncommon cause of chronic CU.

Allergen-Specific IgE Measurement: Intermethod Comparison of Two Assay Systems in Diagnosing Clinical Allergy

BACKGROUND

Our aim was to examine the performance of IMMULITE 2000 assay for specific IgE (sIgE) by comparing it with ImmunoCAP technology in light of a clinical background.

METHODS

Measurements of sIgE were done in a selected patient group (N = 569; varied sample size for each allergen) and in a random sample group (N = 100; 8 allergens). sIgE results were correlated with skin-prick test results (selected patients) and medical history (nonselected patients).

RESULTS

We have detected fair to excellent correlation and agreement between the results of both assays, despite their methodological differences, both in selected and nonselected patient group (ρc = 0.431-0.976; ρc = 0.390-0.972, respectively). Associations of sIgE levels with skin-prick test (SPT) levels and medical history have shown significant correlation for both assays for majority of tested allergens, where applicable (D. pteronyssinus, cat dander, egg white, milk, peanut, orchard grass, Alternaria tenuis, and common ragweed in selected patients; birch, cat dander, common ragweed, D. pteronyssinus, and orchard grass in nonselected; P < 0.05 for all).

CONCLUSIONS

Laboratory testing for sIgE can be successfully accomplished by IMMULITE 2000 immunoanalyzer at a diagnostic accuracy relative to SPT, comparable to the results acquired by CAP technology but not fully comparable on the level of an individual patient.

Added sensitivity of component-resolved diagnosis in hymenoptera venom-allergic patients with elevated serum tryptase and/or mastocytosis

BACKGROUND

Anaphylaxis caused by hymenoptera venom allergy is associated with elevation of baseline serum tryptase (sBT) and/or mastocytosis in about 5% of patients. Up to now, no information has become available on single venom allergen sIgE reactivity and the usefulness of component-resolved approaches to diagnose this high-risk patient group. To address the component-resolved sIgE sensitization pattern and diagnostic sensitivity in hymenoptera venom-allergic patients with elevated sBT levels and/or mastocytosis, a panel of yellow jacket and honeybee venom allergens was applied on a widely used IgE immunoassay platform.

METHODS

Fifty-three patients with mastocytosis and/or elevated sBT tryptase level and systemic reactions to hymenoptera venoms were analyzed for their IgE reactivity to recombinant yellow jacket and honeybee venom allergens by Immulite3 g.

RESULTS

sIgE reactivity to Ves v 1, Ves v 5, Api m 1 to Api m 4 and Api m 10 was found at a similar frequency in hymenoptera venom-allergic patients with and without elevated sBT levels and/or mastocytosis. However, the use of the recombinant allergens and a diagnostic cutoff of 0.1 kUA /L allowed the diagnosis of patients with otherwise undetectable IgE to venom extract. The diagnostic sensitivity of yellow jacket venom allergy using the combination of Ves v 1 and Ves v 5 was 100%.

CONCLUSIONS

In high-risk patients with elevated sBT levels and/or mastocytosis, the use of molecular components and decreasing the threshold sIgE level to 0.1 kUA /L may be needed to avoid otherwise undetectable IgE to hymenoptera venom extracts in about 8% of such patients.

Performance of the PROTIA™ Allergy-Q® System in the Detection of Allergen-specific IgE: A Comparison With the ImmunoCAP® System

PURPOSE

The PROTIA™ Allergy-Q® enzyme immunoassay (EIA) is a recently developed screening assay for specific immunoglobulin E (sIgE) for multiple allergens. The ImmunoCAP® fluorescent EIA (FEIA) system is the most widely used method for sIgE detection. In this study, we evaluated the performance of the Allergy-Q® system compared to the ImmunoCAP® system.

METHODS

We compared the 2 systems using sera from 260 Korean allergy patients suffering from asthma (26.5%), allergic rhinitis (42.3%), atopic dermatitis (67.7%), and food allergy (18.1%). We compared sIgE-measurement results for 7 inhalant allergens, 5 food allergens, and 4 microorganism allergens.

RESULTS

Overall, 1,799 paired assay results were analyzed. Except mugwort and alternaria, most of the allergen-sIgE results showed intra-class correlation coefficients of >0.5. Inter-assay class associations were reliable for most allergens (gamma=0.858-0.987, P<0.001). Passing-Bablok regression analysis showed multiple differences in intercept and slope. The inter-method concordance was moderate to substantial for most allergens (κ=0.713-0.898, P<0.001).

CONCLUSIONS

The PROTIA™ Allergy-Q® EIA system exhibited good detection performance compared to the ImmunoCAP® FEIA system in Korean allergic patients. However, because of methodological differences between the 2 assays, careful clinical implication is required for the interpretation of Allergy-Q® EIA results.

Anaphylaxis to insect venom allergens: role of molecular diagnostics

Anaphylaxis due to Hymenoptera stings is one of the most severe consequences of IgE-mediated hypersensitivity reactions. Although allergic reactions to Hymenoptera stings are often considered as a general model for the underlying principles of allergic disease, diagnostic tests are still hampered by a lack of specificity and venom immunotherapy by severe side effects and incomplete protection. In recent years, the knowledge about the molecular composition of Hymenoptera venoms has significantly increased and more and more recombinant venom allergens with advanced characteristics have become available for diagnostic measurement of specific IgE in venom-allergic patients. These recombinant venom allergens offer several promising possibilities for an improved diagnostic algorithm. Reviewed here are the current status, recent developments, and future perspectives of molecular diagnostics of venom allergy. Already to date, it is foreseeable that component-resolution already has now or will in the future have the potential to discriminate between clinically significant and irrelevant sensitization, to increase the specificity and sensitivity of diagnostics, to monitor immunotherapeutic intervention, and to contribute to the understanding of the immunological mechanisms elicited by insect venoms.

The association of serum 25-OH vitamin D with atopy, asthma, and lung function in a prospective study of Danish adults

BACKGROUND

Besides the important skeletal functions, it has been suggested that vitamin D is involved in the pathogenesis of allergy and asthma and related to lung function. However, previous studies are inconclusive.

OBJECTIVE

The purpose of this study was to investigate associations of serum levels of 25-hydroxy vitamin D (25(OH)D) with atopy, asthma, and lung function in a prospective study of Danish adults.

METHODS

This study included 4999 adults aged 30-60 years in 1999-2001. Three thousand and thirty-two of those included at baseline also participated at a follow-up examination 5 years later, and 3727 answered a 10-year follow-up questionnaire. Serum levels of (25(OH)D) were measured by high-performance liquid chromatography (HPLC) at baseline. No information on use of vitamin D supplements was available. Specific IgE against four common antigens was measured. Information about doctor-diagnosed asthma was obtained from questionnaires, and lung function (FEV1 and forced vital capacity) was measured by spirometry.

RESULTS

We found no significant associations of 25(OH)D with atopy and doctor-diagnosed asthma. However, we found that low levels of 25(OH)D were associated with lower FEV1 percentage predicted (FEV1%pred) in the cross-sectional analyses. The odds ratio (OR) of FEV1%pred < 80% among participants in the highest quartile of 25(OH)D compared with those in the lowest was 0.66 (95% confidence interval (CI): 0.49-0.74). In contrast, prospective analyses indicated an association between high levels of 25(OH)D at baseline and adverse changes in lung function. OR (95%CI) of incident FEV1%pred < 80% was 1.73 (1.06-2.82) in the highest quartile of 25(OH)D compared with the lowest.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data indicates that 25(OH)D levels do not influence the development of asthma and allergy among adults. Further, the results did not consistently support that 25(OH)D levels associate with lung function. Randomized controlled trials are needed to further address this issue.

Label-free colorimetric aptasensor for IgE using DNA pseudoknot probe

The development of simple and low-cost approaches to the detection of immunoglobulin E (IgE) would provide a method for the early diagnosis and prevention of atopic diseases. The current methods of detection are generally tedious, multi-step processes and are limited by the high cost of the labeled proteins. We describe here a label-free structure-switching colorimetric method for the simple measurement of IgE using DNA pseudoknot probes and gold nanoparticles. In the absence of a target the IgE aptamer probe adopts a pseudoknot conformation that dissociates a capture probe from the unmodified gold nanoparticles. However, when IgE binds to the aptamer probe, the pseudoknot is resolved, leading to a favorable hybridization between the 3' terminal loop of the aptamer probe and the capture probe; this induces the aggregation of the gold nanoparticles. As a result, the colorimetric IgE sensor using this structure-switching mechanism is sensitive, specific and convenient, and the assay works even when challenged with complicated biological matrixes such as vaginal fluids. The proposed method is expected to be of great clinical value for IgE detection and could be used, after appropriate design, for sensing applications of other structured aptamers.

[Tricky cases in in-vitro diagnostics of hymenoptera venom allergy]

BACKGROUND

Hymenoptera stings give rise to anaphylactic reactions in 1.2-3.5 % of the population. The risk of repeat anaphylaxis following subsequent stings is greatly reduced through immunotherapy with the culprit venom. A prerequisite for allergen-specific immunotherapy is a precise diagnostic work-up.

AIMS AND OBJECTIVES

We review the efficacy of currently available in-vitro diagnostic tests for hymenoptera venom allergy in different clinical scenarios.

METHODS

A targeted literature review in PubMed and a review of the current guideline on hymenoptera venom allergy were performed. For illustrative purposes, a series of clinical cases from our allergy department are presented.

RESULTS AND CONCLUSION

The correct diagnosis in hymenoptera venom allergy is influenced by a number of factors including patients' ability to identify the insect and time lapsed to diagnostic tests. The high rate of clinically irrelevant sensitizations, cross-reactivity and suboptimal sensitivity of the currently available diagnostic tests further complicate the picture. In the case of multiple sensitizations, molecular allergy diagnostics has improved the detection of clinically relevant sensitizations allowing the cost and risks of unnecessary double immunotherapy to be avoided. This is true in particular with regard to wasp venom allergy. For bee venom allergy, improvements in molecular allergy diagnostics have shown promising results and their implementation in clinical practice is planned. In patients with no sensitization in skin or serological tests but with a convincing history of insect sting anaphylaxis, the increased sensitivity of a basophil activation test may deliver crucial evidence of venom sensitization. The value of the basophil activation test may be further improved using specific marker allergens. The diagnosis of allergy to paper wasps (Polistinae) and white-faced hornets (Dolichovespula) remains problematic as they show partial cross-reactivity to wasp venom and specific marker allergens particular to these, still have to be identified.

Establishing IMMULITE® 2000 cut-off values for serum allergen-specific immunoglobulin and exploring their relationship to exhaled nitric oxide

Aim

Paediatric cut-off values for serum allergen-specific IgE (sIgE) using the Siemens IMMULITE® 2000 system to diagnose allergic rhinoconjunctivitis have not been established. We aimed to determine cut-off levels for sIgE for 10 common inhalant allergens and to study the relationship between sIgE, total IgE and fractional exhaled nitric oxide (FE_NO).

Methods

We enrolled 243 schoolchildren, including 164 with allergic rhinoconjunctivitis. Parental interviews, skin prick tests, sIgE, total IgE, FE_NO measurements, spirometry and exercise tests were performed.

Results

Cut-off values with the best combined sensitivity and specificity were above the detection limit of the assay for seven of the ten allergens (0.23–1.1 kU/L). The overall accuracy of the IMMULITE® in detecting allergic rhinoconjunctivitis was good. sIgE was superior to total IgE and FE_NO in predicting allergic rhinoconjunctivitis to timothy, birch, mugwort, cat, dog and house dust mite. FE_NO was elevated in children with allergic rhinoconjunctivitis, irrespective of asthma.

Conclusion

Cut-off values for sIgE were dependent on the allergic phenotype and were above the IMMULITE® detection limit for seven of ten inhalant allergens. Consequently, using the detection limit for sIgE as the decision point would result in over-diagnosing allergic rhinoconjunctivitis. When measuring elevated FE_NO in children, allergic rhinoconjunctivitis should be suspected.

Comparison of three multiple allergen simultaneous tests: RIDA allergy screen, MAST optigen, and polycheck allergy

We compared the performances of 3 Multiple Allergen Simultaneous Test (MAST) assays: RIDA Allergy Screen (R-Biopharm, Darmstadt, Germany), MAST Optigen allergy system (Hitachi Chemical Diagnostics, Mountain View, CA), and Polycheck Allergy (Biocheck GmbH, Munster, Germany). Forty sera that tested positive with the RIDA Allergy Screen (20 for food and 20 for inhalant panel) were subjected to MAST Optigen and Polycheck Allergy. For 26 available sera with discrepant results, 62 ImmunoCAP allergen-specific IgE tests (Pharmacia Diagnostics, Uppsala, Sweden) were performed. Percent agreements (kappa value) were 87.6% (0.59) and 91.3% (0.60) between RIDA and MAST; 89.9% (0.55) and 88.3% (0.46) between RIDA and Polycheck; and 86.8% (0.51) and 90.6% (0.61) between MAST and Polycheck. Compared with ImmunoCAP, agreements (kappa value) of inhalant and food panels were 51.7% (0.04) and 33.3% (−0.38) for RIDA; 60.7% (0.27) and 81.8% (0.59) for MAST; and 65.5% (0.26) and 45.5% (0.07) for Polycheck. The agreements between RIDA, MAST, and Polycheck and ImmunoCAP-positivity were 45.7%, 88.2%, and 28.6%, respectively, and the agreements for ImmunoCAP-negativity were 37.0%, 51.9%, and 88.9%. MAST Optigen showed better agreement with ImmunoCAP than other assays in the food panel. Better sensitivity of MAST Optigen and better specificity of Polycheck Allergy were suspected.

Between-laboratory quality control of automated analysis of IgG antibodies against Aspergillus fumigatus

Measurement of IgG antibodies against Aspergillus fumigatus is an important criterion for the diagnosis of aspergilloma, allergic bronchopulmonary aspergillosis, and extrinsic allergic alveolitis. In the present study, we compared IgG antibody analysis against A. fumigatus using 2 widely used automated immunochemistry systems. In a between-laboratory quality control program, good agreement was found between the results from laboratories that used the ImmunoCAP system; however, a laboratory that used the Immulite 2000 system found approx. 2-fold higher antibody levels in the quality control samples than did the ImmunoCAP system. Measurements of IgG against A. fumigatus in patient sera were significantly correlated (r(s) = 0.77, P < 0.0001). These results demonstrate that analysis of IgG antibodies against A. fumigatus with these 2 systems has reached a level of standardization that allows for direct comparison of quantitative results from different laboratories. For longitudinal analysis of IgG against A. fumigatus, reagents from the same manufacturer should be used.

Measurement of Hymenoptera venom specific IgE by the IMMULITE 3gAllergy in subjects with negative or positive results by ImmunoCAP

Background

Patients may receive negative results from a specific IgE (sIgE) test such as the ImmunoCAP (CAP) despite a documented history of systemic reaction to a Hymenoptera sting. Thus, further testing may be required using another serological method or venom skin prick tests to confirm allergy diagnosis and correct species.

Objective

To evaluate the sensitivity and the specificity of CAP and IMMULITE 3gAllergy (IMMULITE) for detecting sIgE to Paper wasp (WA) and Yellow Jacket (YJ) venoms using patient clinical history as the comparator.

Methods

Sera from 70 participants with a history of systemic reactions (SR) to WA and/or YJ stings were tested using CAP and IMMULITE. Fifty participants from this group had negative results on CAP. To assess specificity, sera from 71 participants who had never experienced either a WA or YJ sting were tested using CAP and IMMULITE. Fifty participants from this group tested positive using CAP.

Results

In participants with a history of systemic reaction to a Hymenoptera sting, yet who tested negative for WA and/or YJ sIgE according to CAP, the positivity rate according to IMMULITE was 20-42% using 0.10 IU_A/mL as the limit of detection (LoD), per the manufacturer's specification. When the LoD for CAP (0.35 IU_A/mL) was applied to the IMMULITE results, positivity according to IMMULITE was 14-26%. Overall, sensitivity, specificity, and agreement with SR were greater for IMMULITE than for CAP. For YJ: sensitivity (IMMULITE:CAP), 42.8%:28.5%; specificity, 53.5%:39.4%; agreement, 48.2%:34%. For WA, sensitivity (IMMULITE:CAP), 58.6%:28.5%; specificity, 49.3%:47.8%; agreement, 43.9%:38.3%.

Conclusion

The IMMULITE performed well for detecting sIgE to Hymenoptera venom

Specific IgE measurement using AdvanSure® system: comparison of detection performance with ImmunoCAP® system in Korean allergy patients

BACKGROUND

AdvanSure enzyme immunoassay (EIA) system is a recently developed multiple allergen screen test with specific immunoglobulin E (sIgE) detection assay, while ImmunoCAP fluorescent EIA (FEIA) has been widely used for sIgE detection. There has been no inter-assay comparison data for these two systems. We determined the detection performance of AdvanSure system compared to that of ImmunoCAP.

METHODS

We performed an inter-method comparison using sera from 199 Korean allergy patients, including asthma (39.7%), allergic rhinitis (54.8%), atopic dermatitis (36.2%) and food allergies (21.6%). We compared the sIgE detection performance for nine major inhalant and four food allergens.

RESULTS

950 paired assay results were analyzed. Most allergen sIgE results showed above 0.5 intraclass correlation coefficient except Blattella germanica, alternaria and mugwort allergen. Intermethod comparison results showed multiple differences in a few allergens. The inter-method concordance was moderate to substantial for most allergens (κ=0.528-0.778, p<0.001), except for cat dander.

CONCLUSION

AdvanSure system showed a good detection performance compared with ImmunoCAP in correlation and agreement in Korean allergy patients. However, in terms of differences in the methodologies used by these two systems, careful clinical correlation is needed for interpretation of AdvanSure EIA results.

Agreement of specific IgE and skin prick test in an unselected cohort of two-year-old children

The objective of this study was to evaluate the agreement between specific IgE (sIgE) and skin prick test (SPT), and the possible association between total IgE concentration and allergy-related disorders, when performed in an unselected cohort of 353 two-year olds. Median total IgE was within the reference value for two-year-old children regardless of the presence or absence of allergy-related disorders. 18.7% of the children had one or more positive reactions to SPT and/or sIgE in a panel of 12 allergens. Agreement between SPT and sIgE was variable, being best for peanut and poorest for milk.

CONCLUSION

In young children total IgE is of limited value when evaluating allergy-related disorder. The lack of agreement among the positive tests of the sIgE and SPT for some allergens imply that these tests should not be used interchangeably, and both tests should probably be used complementarily when diagnosing atopic sensitization in small children.

Atopy, asthma, and lung function in relation to folate and vitamin B(12) in adults

BACKGROUND

Recent studies suggested low serum folate and impaired folate metabolism as potential risk factors for development of asthma and atopic disease, but the results are inconsistent. The aim of this study was to investigate the relations of markers of folate and vitamin B₁₂ (B₁₂) deficiency with different phenotypes of asthma and atopy.

METHODS

A random sample of 6784 persons from a general population aged 30-60 years participated in a health examination in 1999-2001, and 4516 (66.6%) of those also participated in a follow-up examination 5 years later. The examinations included spirometry, measurements of serum folate and B₁₂, specific IgE to inhalant allergens, total IgE, and genotyping of the MTHFR-C677T polymorphism - a genetic marker of impaired folate metabolism. Information about dietary intake of folate and B₁₂, asthma diagnosis, and airway symptoms was obtained by questionnaires.

RESULTS

Low serum folate levels and the TT genotype of the MTHFR-C677T polymorphism were associated with increased prevalence of self-reported doctor-diagnosed asthma [odds ratio (OR) 1.37, 95% confidence interval (CI) 1.05-1.79 and OR 1.52; 95% CI 1.12-2.06, respectively] and attacks of shortness of breath (OR 1.43, 95% CI 1.14-1.79 and OR 1.47; 95% CI: 1.14-1.91, respectively). We found no significant associations with lung function or atopic outcomes. Serum levels of B₁₂ and dietary intake of folate and B₁₂ were not associated with asthma or atopy.

CONCLUSIONS

We found that two objective markers of folate deficiency were associated with self-reported doctor-diagnosed asthma and attacks of shortness of breath, but not with lung function or atopy.

Determination of multiple allergen-specific IgE by microfluidic immunoassay cartridge in clinical settings

Our aims were to evaluate the performance of an automated microfluidic immunoassay system for measuring allergen-specific IgE (sIgE) in sera against an established in vitro assay and to assess the system's diagnostic accuracy against objective clinical criteria for identifying sensitization to specific allergens in daily practice of allergy clinics. Using both the automated microfluidic-based immunoassay system (BioIC and ImmunoCAP, we measured sIgE in serum samples from 212 children who visited allergic clinics in two medical centers. Outcomes of skin prick tests (SPT) served as the clinical comparison method. The assay results of targeted allergen of BioIC have a good correlation with ImmunoCAP in the diagnosis of allergen sensitivity by patients' clinical history. When comparing the test results of the sIgE against overall allergens, in either two tests among the three assays performed showed high percentage of agreement between BioIC and ImmunoCAP (77.8%, 95% CI: 72-83.3%) but not with SPT (BioIC 64.9%, 95% CI: 58-72%; ImmunoCAP 67.5%, 95% CI: 61-74%). Using ROC analysis and SPT as quasi-standard, BioIC and ImmunoCAP have nearly the same performance of sensitivity and specificity in the confirmation of SPT results. The total and within one-class agreements of each allergen test result between BioIC and ImmunoCAP ranged between 55.2% and 99.5% with an overall average of 80.9%. Laboratory testing for sIgE can be performed on a fully automated, microfluidic cartridge system with advantages of low sample volume, simultaneously tested allergens, and with diagnostic accuracy for representative allergens equivalent to the semi-automated CAP technology.

Association of polymorphisms of the CHI3L1 gene with asthma and atopy: a populations-based study of 6514 Danish adults

Background

YKL-40 is a chitinase-like glycoprotein encoded by the chitinase 3-like 1 gene, CHI3L1, localized at chromosome 1q32.1. Increased levels of serum YKL-40 have been reported to be a biomarker for asthma and a reduced lung function. Interestingly, the C-allele of the -131 C→G (rs4950928) polymorphism of CHI3L1 has been shown to associate with bronchial hyperresponsiveness and reduced lung function suggesting that variations in CHI3L1 may influence risk of asthma. The objective of the present study was to investigate the association of common variation in the CHI3L1 locus with asthma, atopy and lung function in a large population-based sample of adults.

Methods/Principal Findings

Eleven single nucleotide polymorphisms (SNPs) of CHI3L1 including rs4950928 were genotyped in 6514 individuals. Asthma was defined as self-reported history of physician-diagnosed asthma. Total IgE and specific IgE to inhalant allergens were measured on serum samples. Lung function was measured by spirometry. Homozygosity of the rs4950928 G allele as compared to homozygosity of the C allele was associated with self-reported physician diagnosed asthma (OR 1.5 (95% CI, 1.00–2.26)) and with prevalence of atopic asthma (OR 1.93 (95% CI, 1.21–3.07)) after adjustment for age, sex, smoking status, socio-economic class and BMI. Carriers of rs883125 G allele had a significantly lower prevalence of atopy (OR 0.82 (CI, 0.72; 0.94)) as compared to homozygosity of the C allele. None of the SNPs examined were significantly associated with FEV1. However, two SNPs (rs10399931and rs4950930) appeared to be significantly associated with FEV₁/FVC-ratio. Subgroup analyses of never-smokers did not consistently influence the associations in an either positively og negatively way.

Conclusions

In contrast to previous studies, the rs4950928 G allele, and not the C allele, was found to be associated with asthma. A few other SNPs of the CHI3L1 was found to be significantly associated with atopy and FEV1/FVC ratio, respectively. Thus, more studies seem warranted to establish the role of CHI3L1 gene in asthma and atopy.

Aptamer-based piezoelectric quartz crystal microbalance biosensor array for the quantification of IgE

The aim of this study was to develop a rapid method to measure IgE in human serum by use of a direct aptamer-based biosensor based on a quartz crystal microbalance (QCM). An avidin monolayer was applied to immobilize aptamers specific for IgE on the gold surface of a quartz crystal. The frequency shifts (FS) of the QCM were measured and related to IgE concentrations. We could demonstrate that aptamers were able to detect IgE with high specificity and sensitivity in 15 min. A linear relationship existed between the FS (Hz) and the IgE concentrations from 2.5 to 200 microg/L in buffer and human serum. The regression equation was y = 1.03x - 0.06 for this QCM method and chemiluminescence in 50 clinical human serum samples. In addition, the aptamer receptors tolerated repeated affine layer regeneration after ligand binding and recycling of the biosensor with little loss of sensitivity. When stored for 3 weeks, the FS were all greater than 90% of those on the response at the first day. The QCM biosensor can measure IgE and offer advantages of high specificity, reusability, low detection limit, no label or sample pretreatment, and low sample requirement. The aptamer QCM biosensor was suitable for sensitive and specific protein detection, representing an innovative tool for future proteomics.

Allergen-specific IgE measurement with the IMMULITE 2000 system: intermethod comparison of detection performance for allergen-specific IgE antibodies from Korean allergic patients

BACKGROUND

Intermethod comparison between IMMULITE 2000 chemiluminescent enzyme immunoassay (CLEIA) and the established CAP test for allergen-specific IgE (sIgE) has only been evaluated by a few studies.

METHODS

We performed such an interassay comparison using 283 Korean allergic patients with the following: asthma (18.4%), allergic rhinitis (18.4%), both asthma and allergic rhinitis (14.5%), atopic dermatitis (21.9%), and others (26.8%). We compared the sIgE detection performance of both systems for 10 major inhalant allergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae, Blattela germanica, cat dander, dog hair, alder, birch, oak, ragweed, and mugwort) and four food allergens (egg white, cow milk, peanut, and shrimp).

RESULTS

After 645 paired comparison tests, close association and significant correlation were observed between the results of both assays for most of these allergens (r=0.525-0.979, p<0.05, respectively), except for shrimp. Intermethod agreement based on sIgE detection was fair to good (74.1-100%, kappa=0.514-1.000, p<0.05, respectively) for most allergens except for B. germanica, ragweed, and shrimp. Although both assays showed good accuracy in ROC curve analysis, some minor differences were noted.

CONCLUSIONS

IMMULITE 2000 CLEIA for sIgE detection showed fair to good intermethod correlation, association, agreement, and accuracy in comparison to the established CAP assay among Korean allergic patients. However, we should take into account the intermethod differences between both assays for clinical applications.

Accuracy of IgE antibody laboratory results

BACKGROUND

Studies have demonstrated that the magnitude of sensitization as evidenced by specific IgE (sIgE) levels provides significant information as to whether a sensitized individual is likely to be truly reactive. However, it is not clear that quantitative sIgE results provided by different laboratories using different technologies are comparable.

OBJECTIVE

To investigate whether similar results were obtained from Clinical Laboratory Improvement Act-certified laboratories that used 3 common systems for sIgE antibody determination with serum samples and mouse-human IgE chimeric antibodies with known specificity and quantity.

METHODS

Sixty samples for peanut and 20 for soy were submitted for sIgE determination on 3 different systems: ImmunoCAP, Immulite, and Turbo radioallergosorbent test (RAST). Mouse-human chimeric IgE antibodies specific for the major birch allergen Bet v 1 and for the dust mite allergen Der p 2 were also included.

RESULTS

A qualitative evaluation using a cutoff of 0.35 kUA/L showed some differences in the ability to detect sIgE sensitization, with the Turbo RAST being most variable. However, considerable differences were found with quantitative evaluation, with Immulite overestimating and Turbo RAST underestimating sIgE compared with ImmunoCAP. Similar discrepancies were seen with the mouse-human chimeric IgE antibody samples.

CONCLUSION

These findings have potentially serious clinical implications, since each of these systems is widely used. It is therefore important that all laboratories clarify which system they are using. Just because 2 systems present their results in the same units does not mean that the results are necessarily correct or interchangeable.