Performance evaluation of a specific IgE assay developed for the ADVIA centaur immunoassay system

OBJECTIVE: To develop and evaluate a liquid phase immunoassay for accurate determination of allergen-specific IgE (sIgE) as a useful tool in the diagnosis of allergy patients. DESIGN AND METHODS: A fully automated, quantitative sIgE assay was developed for the ADVIA Centaur technology platform using a unique calibration method based on a recombinant reference allergen. Compared to most other IgE-assays, the assay employs a reverse sandwich architecture using monoclonal mouse anti-human IgE antibody covalently bound to paramagnetic particles in the solid phase and capturing the sample IgE. Bound sIgE reacts with liquid biotin-labeled allergen, which is detected as chemiluminescence using acridiniumester-labeled streptavidin. RESULTS: The ADVIA Centaur sIgE assay (Centaur assay) has exclusive reactivity to human IgE and performs with excellent linearity in the assay range 0.35-100 kU/L and high precision (imprecision within-run <2.6%, between-run <4.9%, and total imprecision <7.1%). The analytical sensitivity is <0.10 kU/L. Using Pharmacia CAP system FEIA (CAP) as a comparative method, positive/negative concordance was 94% at 0.35 kU/L cut-off, and the Centaur assay has a sensitivity of 90% and a specificity of 98%. Validation of the assay in a general population sample (The Copenhagen allergy study) revealed that sIgE was highly associated with a clinical diagnosis of inhalation allergy. CONCLUSIONS: The Centaur assay is an allergen-specific assay for measurement of IgE without interference from other types of immunoglobulins or nonspecific IgE. The assay performs with a linear reaction, high assay range, and good reproducibility. The assay correlates well with the CAP system and is in agreement with clinical diagnosis.     

Comparison of allergen-specific IgE levels between Immulite 2000 and ImmunoCAP systems against six inhalant allergens and ten food allergens

Abstract

In vitro allergen-specific immunoglobulin E (sIgE) measurement has been used as an important diagnostic tool for allergic diseases. Currently, quantitative sIgE levels are detected mainly by using ImmunoCAP and Immulite 2000 assay system. These two systems have the same calibration scale at 0–100 kUA/L, but they differ in used allergens, detection methods and automation systems. We compared 1600 paired sIgE results for 204 allergic patients, including 100 paired sIgE assay results for each of 16 allergens (Alternaria alternata, birch-alder mix, cat dander, D. farinae, D. pteronyssinus, dog dander, buckwheat, crab, egg white, mackerel, milk, peach, peanut, shrimp, soybean and wheat flour). Inter-method comparison was performed for qualitative data with a cutoff of 0.35 kUA/L and a detection limit of 0.1 kUA/L, semi-quantitative class results and quantitative data. In qualitative comparisons, the overall concordance rate ranged from 81.0% to 99.0% (k: 0.599–0.949) with the cutoff value of 0.35 kUA/L. It also ranged from 80.0% to 99.0% (k: 0.521–0.951) with the detection limit of 0.1 kUA/L. The class results from these two assays showed good agreements for all allergens. For quantitative sIgE results, these two assays showed moderate positive correlations for Dog dander (r?=?0.683) and Mackerel (r?=?0.573) but high to very high correlations for the other 14 allergens (r?=?0.734–0.972). Immulite 2000 and ImmunoCAP assays demonstrated good concordance and correlation for 16 common allergens, but international standards against each specific allergen for calibration and harmonization of sIgE tests are still needed.     

Cut-off values for total serum immunoglobulin E between non-atopic and atopic children in north-west Croatia.

BACKGROUND: The aim of this study was to determine cut-off values for total serum immunoglobulin E (IgE) between non-atopic and atopic children with respiratory symptoms. Children of 0-16 years of age were evaluated for respiratory symptoms of >4-week duration. METHODS: Children were divided into two groups: non-atopic children (n=3355) who were non-IgE-sensitized with undetectable allergen-specific IgE (<0.35 kIU(A)/L), and atopic children (n=4620) who were sensitized to > or =1 allergens (specific IgE > or =0.35 kIU(A)/L). Upper and lower centiles were determined and cut-off values calculated using receiver operating characteristic (ROC) analysis. RESULTS: Serum total IgE increased with age in both groups, although at a variable level and rate, and reached a plateau at 9 and 10 years in non-atopic and atopic children, respectively. Atopic children had on average 14-fold higher serum total IgE compared to non-atopic children. In both groups, the median was lower than the corresponding mean and the distribution skewness was always positive (group I, 0.87; group II, 0.91). In almost all age groups, the 95th percentile for non-atopic children corresponded to the calculated cut-off values, whereas the 10th percentile for atopic children corresponded to the respective cut-off values only until the age of 8 years, after which greater differences between the cut-off values and the 10th percentile were recorded. Cut-off values for total serum IgE in children up to 16 years were determined with diagnostic sensitivity, specificity and area under the ROC curve of 96%, 91% and 0.950, respectively. CONCLUSIONS: The 95th percentile for total IgE in non-atopic children and the 10th percentile in atopic children could be taken as cut-off values in children up to 8 years of age, after which significant percentile discrepancies between non-atopic and atopic children were recorded. Since atopic subjects show a more irregular centile distribution, cut-off values are best determined by ROC analysis.     

扬州地区变态反应性疾病患者血清中体外过敏原检测与分析

目的分析扬州地区变态反应性疾病患者的主要过敏原种类。方法采用德国AllergyScreen体外过敏原检测系统检测324例变态反应性疾病患者血清中总IgE和过敏原特异性IgE(sIgE)水平。结果324例变态反应性疾病患者总IgE阳性率为79.32%,sIgE阳性率为45.37%。吸入性过敏原阳性率从高到低依次为:户尘螨粉尘螨20.99%,点青霉、分支孢霉、烟曲霉、交链孢霉13.27%,矮豚草、蒿葎草4.32%,蟑螂4.01%,柏、榆、梧桐、柳、三角叶杨树花粉3.09%,猫狗毛皮屑0.62%;食入性过敏原从高到低依次为:牛奶14.20%,牛、羊肉13.89%,腰果、花生、黄豆2.78%,鱼虾蟹1.85%,芒果1.54%,鸡蛋白、鸡蛋黄0.31%。结论变态反应性疾病患者血清中总IgE明显升高,扬州地区吸入性过敏原以螨虫、真菌为主,食入性过敏原以牛奶、牛肉、羊肉为主。大部分患者只对1~2种过敏原过敏。     

Generation of human monoclonal allergen-specific IgE and IgG antibodies from synthetic antibody libraries

BACKGROUND: Allergen-specific IgE and IgG antibodies play pivotal roles in the induction and progression of allergic hypersensitivity reactions. Consequently, monoclonal human IgE and IgG4 antibodies with defined specificity for allergens should be useful in allergy research and diagnostic tests. We used combinatorial antibody libraries and subsequent recombinant production to make and assess IgE, IgG1, and IgG4 allergen-specific antibodies. METHODS: We used phage display to select a synthetic single-chain antibody fragment (scFv) library against 3 different allergens, from bee venom, bovine milk, and apple. The scFv obtained were converted into IgG1, IgG4, and IgE antibody formats and assessed for their biochemical properties by ELISA, immunoblotting, and fluorescence-activated cell sorting. RESULTS: Two different antibody formats for each IgG1, IgG4, and IgE antibody were produced in mammalian cells as disulfide-linked and glycosylated Ig, which were usable in allergen-specific ELISA assays and immunoblots. In addition, the recombinant IgE antibodies mediated the binding of allergens to HEK-293 cells transfected with the high-affinity IgE receptor, and this binding was blocked by corresponding IgG antibodies. CONCLUSIONS: The use of synthetic libraries for the generation of allergen-specific recombinant IgE and IgG antibodies should have broad applications in allergological research and diagnosis.     

Performance validation of a third-generation allergen-specific IgE assay in the clinical laboratory: interlaboratory and intermethod comparison

BACKGROUND: Allergen-specific IgE (sIgE) measurements are used to help identify causative allergenic agents and to determine the degree of sensitization to facilitate treatment decisions. We examined the performance of a new third-generation chemiluminescent enzyme immunoassay for allergen-specific IgE (sIgE) on the continuous random access Immulite 2000 system. METHODS: Detection limit and dilutional linearity were determined. Within-run and total precision were assessed according to the NCCLS EP5 guideline. Interlaboratory comparison of the new Immulite 2000 third-generation allergen-specific IgE assay was performed, as well as intermethod comparison against the Pharmacia FEIA, a second-generation assay. RESULTS: The detection limit was <0.1 kU/l. Dilutional linearity held from 100 down to 0.2 kU/l. Regression analysis of the interlaboratory comparison results yielded: Immulite 2000(Laboratory 1)=1.07 Immulite 2000(Laboratory 2)+0.18 kU/l; r=0.98, n=3588 results. Intermethod comparison showed the following: Immulite 2000=0.83 (Pharmacia FEIA)+0.42 kU/l; r=0.79, n=512 results. Bland-Altman analysis of the interlaboratory and intermethod comparisons indicated no systematic bias. CONCLUSIONS: We confirmed the reported performance characteristics of the third-generation sIgE assay and found reasonably good interlaboratory and intermethod agreement. The extended range capability of the third-generation assay provides a new tool for investigating cutoffs and trends in childhood allergy disease progression at concentrations <0.35 kU/l.     

Ⅰ型变态反应疾病中特异性IgE变应原引起的单一致敏和多重致敏的变应原分布特征研究

目的 研究Ⅰ型变态反应疾病中特异性IgE(specific IgE,sIgE)变应原在单一致敏和多重致敏中的分布特征。方法 选取2014年10月～2017年9月徐州市医学科学研究所确诊的Ⅰ型变态反应疾病患者767例作为研究对象,免疫印迹法检测患者血清中19种变应原sIgE,分析单一致敏和多重致敏比例、sIgE变应原在单一致敏和多重致敏中的阳性率及分布。结果 sIgE变应原引起的单一致敏和多重致敏分别为414例(53.98%)和353例(46.02%),户尘螨和混合霉菌在单一致敏和多重致敏中的分布接近(49.0% vs 51.0%和43.4% vs 56.6%),并且在不同数量变应原致敏的多重致敏中阳性率相对稳定,其他17种变应原75%～100%分布在多重致敏中,阳性率随致敏变应原种类增加而增高。单一致敏中最主要变应原为户尘螨(64.8%)和混合霉菌(19.0%),其次是牛奶(3.9%)和蟑螂(2.2%)。多重致敏中各变应原阳性率均高于单一致敏,差异均有统计学意义(χ2=5.598～137.2,均P<0.05),在种属相近的变应原之间呈现出高度一致的阳性现象。结论 Ⅰ型变态反应疾病中单一致敏和多重致敏的sIgE变应原分布有显著差异,多重致敏中可能存在广泛的交叉致敏。     

CAP系统检测过敏原特异性IgE抗体的方法学评价

目的 评价CAP过敏原检测系统检测过敏原特异性IgE抗体的准确性和预测值。方法 研究对象为2003～2004年就诊的病例,结合病史和体内试验结果做出过敏原特异性的临床诊断。对其中明确诊断为尘螨、蒿属花粉、律草花粉、猫毛屑或链格孢霉5种过敏原过敏者用CAP过敏原检测系统进行相应的过敏原特异性IgE检测,并随机选取部分临床明确诊断对上述5种过敏原不过敏者同时进行相应过敏原特异性IgE检测,分析CAP系统检测的准确性并计算其阳性预测值和阴性预测值。结果 共进行了957项次过敏原特异性IgE检测,对尘螨、蒿属花粉、律草花粉、猫毛屑、链格孢霉特异性IgE检测的灵敏度分别为99．0％、97．9％、91．7％、93．5％、85．5％,特异性分别为96．2％、95．8％、93．0％、97.0％、91．7％。特异性IgE检测结果与临床诊断之间的符合率较高,阳性预测值均大于94％,阴性预测值均大于80％。结论 用CAP过敏原检测系统检测过敏原特异性IgE抗体的结果准确性好,预测值高,表明该方法具有较高的实用诊断价值。     

Evaluation of a particle-enhanced turbidimetric immunoassay for the measurement of immunoglobulin E in an ILab 900 analyzer.

BACKGROUND: The measurement of immunoglobulin E (IgE) in serum is widely used in the diagnosis of allergic reactions and parasitic infections. We describe here a fully automated assay for human IgE suitable for routine application in a general chemistry analyzer. METHODS: We used an ILab 900 analyzer. This instrument automates a particle-enhanced immunoturbidimetric assay with an analysis time of 9 min. RESULTS: The assay was linear in the range 4-1000 kIU/L (r = 0.9998). The intra- and interassay CVs at 57, 235, and 434 kIU/L were <3.5% and <7.4%, respectively. The detection limit was 4 kIU/L. Hemoglobin (相似文献   

176例儿童过敏性紫癜过敏原特异性IgE和总IgE水平检测

目的探讨过敏性紫癜患者血清中过敏原特异性IgE和总IgE水平。方法采用德国敏筛过敏原定量检测系统,检测176例过敏性紫癜患者血清过敏原特异性IgE和总IgE水平。结果176例过敏性紫癜患者中,血清过敏原特异性IgE抗体阳性者78例,占44.3%,血清总IgE>100者31例,占17.6%。吸入组过敏原阳性率依次为户尘螨粉尘螨、点青霉分枝孢霉曲霉交链孢霉、矮豚草蒿、柏榆梧桐柳三角叶杨、蟑螂、猫毛皮屑狗毛皮屑、草;食物组阳性率依次为鱼虾蟹、鸡蛋白鸡蛋黄、牛奶、牛肉羊肉、腰果花生黄豆、芒果、小麦。结论吸入物和食物过敏原诱导的变态反应是导致过敏性紫癜的重要因素之一。     

Histamine release test and measurement of antigen-specific IgE antibody in the diagnosis of allergic conjunctival diseases

Although systemic allergic laboratory tests for the quantification of allergen-specific serum IgE antibody have been widely used, in these tests a high titer of serum specific IgE does not necessarily indicate evidence of allergy. We evaluated the diagnostic value of the glass microfiber-based histamine release test (HRT) using small amounts of whole blood, in 36 cases of allergic conjunctival diseases: 17 cases of allergic conjunctivitis and 19 of atopic keratoconjunctivitis. The patients were evaluated by HRT, capsulated hydrolic carrier polymer (CAP)-RAST, and conjunctival provocation test (CPT) against ten allergens. The positive rates for all allergens were higher in CAP-RAST than in HRT. The mean concordance of HRT with CAP-RAST results was 0.789. The mean concordance of HRT with CPT was 0.892 and that of CAP-RAST with CPT was 0.693. A significantly higher concordance was observed in HRT than CAP-RAST for Japanese cedar and mite antigen. The mean sensitivity, specificity, and efficiency of HRT were higher than those of CAP-RAST. These results indicate that CAP-RAST is good for the screening of allergens and that HRT has an advantage in the confirmation of clinical allergens in allergic conjunctival diseases because of its high sensitivity, specificity, efficiency, and higher concordance with CPT.     

呼出气一氧化氮对哮喘的诊断作用及与过敏原sIgE的关系

目的探讨呼出气一氧化氮(FeNO)对哮喘的诊断作用及与过敏原特异性IgE抗体(sIgE)的关系。方法选取2017年8月至2019年8月收治的98例疑似哮喘患儿进行观察,收集所有患儿的临床特征指标,检测肺功能及FeNO浓度,分析FeNO对哮喘的诊断作用及其与过敏原sIgE的关系。结果哮喘组的FeNO水平高于非哮喘组(P<0.05)。血清过敏原sIgE阳性患儿的Fe NO水平高于阴性患儿(P<0.05)。经Pearson相关性分析得出,FeNO水平与血清过敏原sIgE、血清总IgE和血清过敏原种类呈显著正相关(r=0.703、0.624、0.719,P<0.05)。结论FeNO在哮喘中具有一定的诊断价值,与过敏原sIgE存在显著的相关性,可为临床诊断与治疗哮喘提供有利参考依据。     

Measurement of IgE antibodies using liquid allergens--an inter-method and inter-laboratory quality assessment

BACKGROUND: The determination of IgE antibodies is important for the in vitro diagnosis of allergic diseases. However, not all systems currently available in the market fulfill essential quality criteria, e.g. regarding characteristics such as sensitivity and specificity, and the data do not always reflect true clinical relevance in the required fashion. Recent innovations may reduce the workload for the technician, and thus help save time and money. More importantly, they might reduce potential sources of error. OBJECTIVE: Two allergy systems, the well established Pharmacia CAP system that uses the allergens conventionally in a solid phase and the ALLERgen system that employs liquid allergens, were compared with regard to quality criteria and practicability. METHODS: Defined serum pools were checked for within-run and between-days imprecision of IgE antibody detection in two independent laboratories. Serum specimens from allergic patients and controls were tested in parallel using both methods for total and antigen-specific IgE antibody detection under standardized conditions. In addition, one laboratory working exclusively with the ALLERgen system participated in the Austrian inter-laboratory quality assessment program. RESULTS: The two systems were comparable in terms of sensitivity and specificity, and also showed good correlation. Within-run evaluations were excellent for total IgE and antigen-specific IgE, and the between-days imprecision was satisfactory. Coefficients of variation were within an acceptable range for the different groups of allergens. In the external quality control program the data obtained with the ALLERgen system showed good concordance with other systems in use; up to 94% of the results were identical when considering clinically relevant sensitizations. Regarding practicability, both systems were most satisfactory for the operator. The ALLERgen system offered a certain advantage in terms of automated operation, which resulted in shorter fixed and variable phases of personnel time. CONCLUSION: Both the Pharmacia CAP system and the ALLERgen system belong to an advanced generation of allergy test systems and are easy to handle. The reproducibility of results is good with both methods, and the imprecision data fall within an acceptable range. Thus, the ALLERgen system is a reliable in vitro system for evaluating specific and total IgE in serum, providing data equivalent to those obtained with the CAP system.     

Allergy testing on the IMMULITE 2000 Random-Access immunoanalyzer - a clinical evaluation study.

PURPOSE: We aimed to evaluate the diagnostic performance of the IMMULITE 2000 Allergy System from Diagnostic Products Corporation (DPC) for the detection of inhalant and food allergies, focusing on inhalant and food screens, mixes and single allergens. METHODS: Serum samples were collected from new, unselected patients who were referred to the allergist for a suspected allergy. Patients were classified as study diagnosis-positive for inhalant (food) allergy if they had both a positive clinical examination/history and a positive skin test for inhalant (food) allergy; otherwise - failing one or both of these criteria - they were classified as study diagnosis-negative. Classification and testing of the serum samples was carried out in a blinded fashion. Values greater than 0.35 kU/L were considered positive. RESULTS: Of the 118 patients included, 63 were considered study diagnosis-positive for inhalation and/or food allergy. DPC inhalation screening showed 82% total agreement (TA) and 91% sensitivity relative to the study diagnoses. The DPC food panel showed 96% TA and 98% specificity relative to the study diagnoses. Relative to specific intracutaneous testing (ICT), the DPC D1, E1 and E5 assays had sensitivity of 82-90%; tree and grass panels had sensitivity of 74% and 95%. The DPC weed panel and initial lots of DPC E5 had poor sensitivity (<40%); mold panel sensitivity was equally low for both DPC and the routinely used Pharmacia assay (36%). Relative to skin prick testing (SPT), specific food allergens had TA of 94-98% and specificity of 95-100%. CONCLUSION: In patients classified by the combination of clinical examination/history and skin test results, the DPC IMMULITE 2000 Allergy System generally demonstrated acceptable sensitivity, specificity and TA compared to the study diagnoses, both at the screening level and at the level of panels and single allergens.     

交叉反应性糖类决定簇IgE对血清特异性IgE检测的影响

目的分析血清变应原特异性IgE(specific IgE,sIgE)检测结果与调查对象实际情况不符合率,探讨交叉反应性糖类决定簇IgE(IgE to carbohydrate cross-reactive determinants,CCD-IgE)对血清sIgE检测的影响。方法通过问卷方式收集1 715例体检人群资料,用斑点免疫印迹法(dot-IBT)检测血清CCD-IgE及19种变应原sIgE。结合问卷与sIgE检测结果,分析sIgE检测阳性与问卷不符合情况及CCD-IgE对sIgE检测的影响。结果各类变应原sIgE检测均存在与问卷主诉不符合的情况,其中花生最高(47.06%);sIgE阳性级别较低时不符合率相对较高;CCD-IgE阳性时较阴性时变应原sIgE阳性率较高(P<0.05);疑似变态反应病组和健康人组不符合者中CCD-IgE阳性率比较,差异有统计学意义(P<0.05)。结论 CCD可能与血清变态反应原sIgE发生交叉反应,当存在sIgE检测与临床实际情况不符合时应考虑CCD的影响。     

Diagnostic and analytical performance of a screening panel for allergy.

Worldwide, allergic diseases are increasing in prevalence and incidence. Early assessment of the immunoglobulin E (IgE) sensitisation status has a major impact on clinical outcome and selection of therapeutic options. Recently, a number of new IgE-detecting test systems have entered the market, including screening tests allowing identification of a wide spectrum of sensitising allergens. We evaluated the analytical and diagnostic performance of the newly developed Allergy Screen test panel for atopy (Mediwiss Analytic, Moers, Germany). The evaluation was performed for four major respiratory and four major nutritional allergens in 142 patients with clinical suspicion of respiratory and/or food allergies. For all allergens, the test showed acceptable concordance to the skin-prick test and the in vitro IgE CAP system (Pharmacia, Freiburg, Germany). The analytical performance was acceptable, with CVs between 2 and 8% in the positive range and good dilution linearity (R=0.9735). Imprecision in the low IgE concentration range dramatically improved by lowering the cut-off value to 0.2 IU/mL IgE. In conclusion, the Allergy Screen panel yields reliable results in the detection of allergic sensitisation to common allergens.     

Clinical associations with serum allergen-specific IgG4 antibodies

Serum total and allergen-specific IgE and IgG4 antibodies, were measured in eighty-seven atopic and nineteen non-atopic asthmatics. The allergens studied were: Dermatophagoides pteronyssinus, grass pollens, cat dander, dog dander, milk and egg. Sixty-eight atopic asthmatics and fourteen non-atopic asthmatics were found to have allergen-specific IgG4 antibodies, to at least one of the allergens tested. IgG4 antibodies to milk and egg were common in both groups of asthmatics, and to animal danders in the non-atopic asthmatics. Skin prick tests were always negative when allergen-specific IgG4 antibodies occurred alone, but in such cases, intradermal skin tests were positive. Seventy-five per cent of a group of patients with normal levels of serum total IgG4, were found to have at least one positive IgG4 RAST.     

364例儿童慢性湿疹血清特异性IgE和总IgE检测分析

目的了解慢性湿疹患儿血清特异性IgE和总IgE水平,为预防和治疗该病提供理论依据。方法采用德国Mediwiss过敏原体外检测系统,应用免疫印迹定量法对364例慢性湿疹患儿进行血清特异性IgE和总IgE检测。结果慢性湿疹患儿总IgE阳性检出率为48．9％;吸入变应原中户尘螨粉尘螨、蟑螂、矮豚草蒿、狗猫皮屑、霉菌阳性检出率分别为29．7％,14．3％,13．5％,12．6％,12．1％;食入变应原中蛋白蛋黄、牛奶、鱼虾蟹阳性检出率分别为18．1％,15．9％,12．6％;1—3岁组食入性变应原的阳性率为高于6—12岁组（P〈0．05）,而吸入性变应原的阳性率则低于6—12岁组（P〈0．05）。结论尘螨、蟑螂、矮豚草蒿、猫毛狗毛皮屑、霉菌、鸡蛋、牛奶、鱼虾蟹是吉林地区小儿慢性湿疹常见的变应原。小于3岁湿疹患儿主要对蛋白蛋黄等食入性变应原过敏,而大于6岁患儿主要对粉尘螨、蟑螂、矮豚草蒿等吸入性变应原过敏。     

Simultaneous determination of total IgE and allergen-specific IgE in serum by the MAST chemiluminescent assay system

We have developed a chemiluminescent immunoenzymometric system. The first commercial application of this chemiluminescent assay (CLA) is the measurement of total IgE and allergen-specific IgE in human serum. The CLA system is a second-generation adaptation of the MAST RIA allergy profiling system. The MAST CLA system assay protocol consists of three steps: overnight incubation of serum, a 4-h incubation with enzyme-labeled antibody, and a 30-min chemiluminescent reaction, which produces a visible image (immunograph) on high-speed Polaroid instant film. The densities of the bands produced on the film are quantified with an inexpensive microprocessor-controlled infrared transmittance densitometer. The novel luminogenic substrates used yield a constant light output for over 2 h with an intensity at least 10-fold greater than that of commercial chemiluminescent reagents. The MAST CLA system exhibits sensitivity, specificity, and precision equal to that of the MAST RIA system (r = 0.96 for 40 serum samples analyzed with 25 allergens). As many as 35 different allergens per sample can be quantified in a single assay. The MAST CLA system requires no standard curve or volume-dependent pipetting steps, incorporates both positive and negative controls for each sample, and quantifies allergen-specific IgE at picomolar concentrations.     

Comparison of four in vitro assays for specific IgE detection

Summary Three immunoenzymatic techniques for specific IgE detection (Pharmacia CAP System, Kallestad Allercoat System, Neo Abellò Hamlet-IgE) and the classical Phadebas RAST were compared using 34 sera from patients with a clinical diagnosis of allergic disease and 19 sera from healthy non-atopic controls. IgE antibodies to 9 aeroallergens and 6 food antigens were assessed and 399 tests were run with each method. All techniques showed a high specificity (92%–100%) and satisfactory efficiency (82%–98%), while the sensitivity for RAST, CAP, Allercoat and Hamlet was 89%, 91%, 83% and 53%, respectively, with the lowest values for food allergens. There was a good overall correlation of the four techniques, except when the Hamlet method was compared with the other methods for food-specific IgE detection (correlation coefficient <0.3). These data indicate that CAP, Allercoat and RAST are satisfactory techniques for specific IgE determination, either for inhalants or for food allergens; CAP, however, offers the highest sensitivity without loss of specificity.