Antibody testing in aspergillosis--quo vadis?

Aspergillus-specific antibodies - Targets and applications

Aspergillus is a fungal genus comprising several hundred species, many of which can damage the health of plants, animals and humans by direct infection and/or due to the production of toxic secondary metabolites known as mycotoxins. Aspergillus-specific antibodies have been generated against polypeptides, polysaccharides and secondary metabolites found in the cell wall or secretions, and these can be used to detect and monitor infections or to quantify mycotoxin contamination in food and feed. However, most Aspergillus-specific antibodies are generated against heterogeneous antigen preparations and the specific target remains unknown. Target identification is important because this can help to characterize fungal morphology, confirm host penetration by opportunistic pathogens, detect specific disease-related biomarkers, identify new candidate targets for antifungal drug design, and qualify antibodies for diagnostic and therapeutic applications. In this review, we discuss how antibodies are raised against heterogeneous Aspergillus antigen preparations and how they can be characterized, focusing on strategies to identify their specific antigens and epitopes. We also discuss the therapeutic, diagnostic and biotechnological applications of Aspergillus-specific antibodies.

Aspergillus precipitating antibody in patients with Mycobacterium avium complex lung disease: A cross-sectional study

RATIONALE

Little is known about the role of Aspergillus precipitating antibody (APAb) in patients with Mycobacterium avium complex lung disease (MAC-LD).

OBJECTIVES

We investigated the clinical characteristics of patients with MAC-LD positive for APAb.

METHODS

We conducted a cross-sectional study targeting patients with MAC-LD. APAb was checked in all participants. Clinical variables included laboratory data, pulmonary function, high-resolution computed tomography findings, and health-related quality of life.

RESULTS

We analyzed 109 consecutive patients. Their median age was 68 years, and the median duration of MAC-LD was 4.8 years. Twenty (18.3%) patients tested positive for APAb. APAb-positive patients had significantly longer duration of MAC-LD (9.4 vs. 4.0 years, P = 0.017), more severe bronchiectasis evaluated by modified Reiff score (6.5 vs. 4, P = 0.0049), and lower forced expiratory volume in 1 s (%FEV₁) (75.1% vs. 86.2%, P = 0.013) than APAb-negative patients. Analysis of covariance adjusted for background factors and underlying pulmonary disease revealed that %FEV₁ was also significantly lower in patients with APAb (P = 0.045). Ten patients were newly diagnosed with chronic pulmonary aspergillosis (N = 5) or allergic bronchopulmonary aspergillosis (N = 5).

CONCLUSIONS

APAb is associated with lower pulmonary function, and observed especially in patients with longer duration of MAC-LD and severe bronchiectasis, even in the absence of cavitary lesions.

Evaluation of a commercial quantitative Aspergillus fumigatus-specific IgM assay for the diagnosis of invasive pulmonary aspergillosis

Invasive pulmonary aspergillosis (IPA) is a common fungal infection with high mortality rates in immunocompromised patients. Early diagnosis of IPA is still challenging because of its nonspecific clinical symptoms and radiological presentations.To evaluate the clinical value of a commercial Aspergillus fumigates-specific IgM antibody assay in diagnosis of IPA, a multicenter prospective study was performed in 12 hospitals in Zhejiang Province, China, from January 1 to December 31, 2016.A total of 59 patients were enrolled in this study, including 30 IPA and 29 non-IPA patients. The sensitivities of IgM assay were 30.0%, 26.7%, 23.3%, and 20.0%, and the specificities were 79.3%, 86.2%, 86.2%, and 96.6% at the cutoff values of 50, 60, 70 and 80 AU/mL, respectively. The area under the curve of the IgM assay revealed by the receiver-operating characteristic analysis was 0.511 in the IPA cases. This study is the first to evaluate the clinical performance of a commercial A. fumigatus-specific IgM antibody assay that uses envelopes galactomannan extracted from A. fumigatus as the sole antigen in diagnosis of IPA.In conclusion, the A. fumigatus-specific IgM antibody assay has limited value and should not be a prior recommendation for IPA diagnosis.

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.

Clinical features and diagnosis of chronic pulmonary aspergillosis in Chinese patients

Chronic pulmonary aspergillosis (CPA) has recently been recognized as a significant global health burden. In China, the diagnosis of CPA is still unfamiliar to most doctors. The aim of this study was to demonstrate the clinical manifestations and diagnoses of CPA in China.A multidisciplinary team of doctors retrospectively screened 690 records of patients diagnosed with pulmonary aspergillosis from January 2000 to December 2016 at Peking Union Medical College Hospital, Beijing, China. Of these, 69 patients were diagnosed with CPA. The patients' clinical characteristics were then retrieved and analyzed. Demographic, laboratory, and radiological data for these patients were compared by CPA type.Of the 69 patients diagnosed with CPA, 10 patients were diagnosed with chronic cavitary pulmonary aspergillosis (CCPA), 15 patients with semi-invasive aspergillosis (SAIA), 41 patients with simple aspergilloma, and 3 patients with Aspergillus nodule. Further, 53.3% of the SAIA patients were obviously immunocompromised, and 60% of the CCPA patients, 26.7% of the SAIA patients, 7.3% of the simple aspergilloma cases were mildly immunocompromised. Previous underlying lung abnormalities were observed in 20% of CCPA patients, 53.3% of SAIA patients, and 80.5% of simple aspergilloma patients. The most common symptoms in the CPA patients were cough (92.8%), hemoptysis (63.8%), chronic sputum (23.2%), and fever (17.4%). The most common computerized tomography abnormalities were cavities (94.2%), nodule (84.1%), consolidation (4.3%), pleural thickening (2.9%), and infiltration (2.9%). CCPA, SAIA and simple aspergilloma patients were significantly different with respect to their course before diagnosis, constitutional symptoms, fever, hemoptysis, breathlessness, white blood cell count, erythrocyte sedimentation rate, high-sensitivity C-reactive protein count, presence of nodule, and presence of a solitary lesion (all P < .05). Furthermore, SAIA patients had a significantly shorter course before diagnosis and a significantly higher white blood cell count compared with CCPA patients (both P < .01).In China, underlying systemic immunocompromising conditions and lung diseases with mechanical impediments contribute to CPA. Simple aspergillosis was the most common diagnosis in CPA patients. The imaging characteristics of simple aspergillosis and Aspergillus nodules were quite discriminable, while CCPA, and SAIA were similar in their clinical and radiological features. Distinguishing between CCPA and SAIA depends mainly on the physician's clinical judgment.

Laboratory Diagnostics for Fungal Infections: A Review of Current and Future Diagnostic Assays

This article reviews the current diagnostic approaches, both serologic and molecular, for the detection of fungi associated with pulmonary disease. Classic serologic techniques, including immunodiffusion and complement fixation, both of which remain a cornerstone for fungal diagnostic testing, are reviewed and their performance characteristics presented. More recent advances in this field, including novel lateral-flow assays for fungal antigen detection, are also described. Molecular techniques for fungal identification both from culture and directly from patient specimens, including nucleic acid probes, mass spectrometry-based methods, nucleic acid amplification testing, and traditional and broad-range sequencing, are discussed and their performance evaluated.

Proteomics as a Tool to Identify New Targets Against Aspergillus and Scedosporium in the Context of Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disorder that increases the risk of suffering microbial, including fungal, infections. In this paper, proteomics-based information was collated relating to secreted and cell wall proteins with potential medical applications from the most common filamentous fungi in CF, i.e., Aspergillus and Scedosporium/Lomentospora species. Among the Aspergillus fumigatus secreted allergens, β-1,3-endoglucanase, the alkaline protease 1 (Alp1/oryzin), Asp f 2, Asp f 13/15, chitinase, chitosanase, dipeptidyl-peptidase V (DppV), the metalloprotease Asp f 5, mitogillin/Asp f 1, and thioredoxin reductase receive a special mention. In addition, the antigens β-glucosidase 1, catalase, glucan endo-1,3-β-glucosidase EglC, β-1,3-glucanosyltransferases Gel1 and Gel2, and glutaminase A were also identified in secretomes of other Aspergillus species associated with CF: Aspergillus flavus, Aspergillus niger, Aspergillus nidulans, and Aspergillus terreus. Regarding cell wall proteins, cytochrome P450 and eEF-3 were proposed as diagnostic targets, and alkaline protease 2 (Alp2), Asp f 3 (putative peroxiredoxin pmp20), probable glycosidases Asp f 9/Crf1 and Crf2, GPI-anchored protein Ecm33, β-1,3-glucanosyltransferase Gel4, conidial hydrophobin Hyp1/RodA, and secreted aspartyl protease Pep2 as protective vaccines in A. fumigatus. On the other hand, for Scedosporium/Lomentospora species, the heat shock protein Hsp70 stands out as a relevant secreted and cell wall antigen. Additionally, the secreted aspartyl proteinase and an ortholog of Asp f 13, as well as the cell wall endo-1,3-β-D-glucosidase and 1,3-β-glucanosyl transferase, were also found to be significant proteins. In conclusion, proteins mentioned in this review may be promising candidates for developing innovative diagnostic and therapeutic tools for fungal infections in CF patients.

Is Bulpa criteria suitable for the diagnosis of probable invasive pulmonary Aspergillosis in critically ill patients with chronic obstructive pulmonary disease? A comparative study with EORTC/ MSG and ICU criteria

Background

Three diagnostic criteria have been proposed used for invasive pulmonary aspergillosis (IPA) diagnosis, namely EORTC/ MSG criteria, Bulpa criteria and intensive care unit (ICU) criteria. The Bulpa criteria were proposed to diagnose IPA in chronic obstructive pulmonary disease (COPD) patients specially. Our aim is to verify that whether the Bulpa criteria are the most suitable for diagnosing probable IPA in critically ill COPD patients compared with the other two criteria.

Methods

We included critically ill COPD patients admitted to the ICU from April 2006 to August 2013. Patients were classified into four populations: population one (n₁ = 59) comprised all included patients; population two (n₂ = 24) comprised patients with positive mycological findings (both positive cultures and positive serologic tests); population three (n₃ = 18) comprised patients with positive lower respiratory tracts (LRTs) isolation; and population four (n₄ = 5) comprised proven IPA patients with histopathology. Patients in four groups were diagnosed as probable IPA using three criteria respectively, and the “diagnostic rate” of each criteria were compared with each other. Then, the reasons for differences in “diagnostic rate” were analyzed in population two. Finally, the modified Bulpa criteria were proposed.

Results

Bulpa criteria yielded the highest “diagnostic rate” of probable IPA followed by the ICU criteria, while the EORTC/ MSG criteria provided the lowest rates in four populations (the “diagnostic rate” of probable IPA was 33.9%, 16.9% and 6.8% in population one, p = 0.001; 83.3%, 41.7% and 16.7% in population two, p < 0.001; 100%, 55.6% and 22.2% in population three, p < 0.001; 100%, 60% and 20% in population four, p = 0.036). The reasons for the highest “diagnostic rate” by Bulpa criteria were its less strict requirements regarding the doses/courses of steroid use and typical computed tomography (CT) findings. Finally, the modified Bulpa criteria for probable IPA were proposed for critically ill COPD patients admitted to ICU, mainly involving revised interpretations of microbiological findings.

Conclusions

Among the existing three criteria, the Bulpa criteria are the most suitable for diagnosing probable IPA in critically ill COPD patients admitted to ICU. A modified criteria maybe proposed for better diagnosis,and its clinical validity need to be verified in future studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2307-y) contains supplementary material, which is available to authorized users.

Challenges in microbiological diagnosis of invasive Aspergillus infections

Invasive aspergillosis (IA) has been increasingly reported in populations other than the historical hematology patients and there are new questions about the performance of microbiological tools. Microscopy and culture have been completed by biomarkers, either antigens or DNA, and in blood or respiratory specimens or both. First studied in hematology, the antigen galactomannan performance in serum is low in other patient populations where the pathophysiology of the infection can be different and the prevalence of IA is much lower. DNA detection with polymerase chain reaction (PCR) in blood or serum (or both) has reached a certain level of acceptance thanks to consensus methods based on real-time quantitative PCR (qPCR). When used on respiratory specimens, galactomannan and qPCR depend on standardization of the sampling and the diverse mycological procedures. Thus, culture remains the main diagnostic criterion in critically ill patients. The current trend toward more effective anti-mold prophylaxis in hematology hampers the yield of a screening strategy, as is usually performed in hematology. Therefore, circulating biomarkers as confirmatory tests should be considered and their performance should be reappraised in each new setting. The use of azole prophylaxis also raises the issue of selecting azole-resistance Aspergillus fumigatus isolates. Ideally, the biomarkers will be more efficient when individual genetic risks of IA are defined. Culture, though not standardized, remains a key element for the diagnosis of IA and has the advantage to easily detect molds other than A. fumigatus. It is still unclear whether next-generation sequencing will replace culture in the future.

Immunological Identification of Fungal Species

Immunodetection is described in this chapter as a technique for producing specific antibodies for antigen detection of the major human fungal pathogens. In the case of Candida spp., heat-killed cells are used to immunize mice over a couple of weeks and then splenocytes are isolated and further fused with myelomas to easily propagate the antibodies produced in the mice. The resulting antibodies follow a purification process where antibody levels and concentrations are determined. Fungal cells are also lysed to obtain whole cell extracts as a prior step for identification of antigens using immunoprecipitation. Finally, this method permits the production of specific antibodies against fungi and the identification of the respective antigens in an in vivo model.

Aspergillus serology: Have we arrived yet?

Aspergillosis presents in various clinical forms, among them chronic pulmonary aspergillosis, which is a spectrum of disease entities including aspergilloma, chronic cavitary pulmonary aspergillosis, and chronic fibrosing pulmonary aspergillosis. Aspergillus also contributes to fungal allergy and sensitization. Analysis of the immune response to Aspergillus and its antigens is an integral part of the diagnosis of these diseases. Over the past half century, the techniques used to determine antibody titers have evolved from testing for precipitating and agglutinating antibodies by agar gel double diffusion and immunolectrophoresis to enzyme-linked immunosorbent assays using recombinant proteins as capture antigens. A resurgence of interest in the detection of immunoglobulins, primarily Aspergillus-specific IgG, has hinted at the possibility of distinguishing between colonization and invasion in immunocompromised patients with invasive aspergillosis. Even though there appears to be a greater degree of discrimination between the clinical forms of aspergillosis there is still a long way to travel. This review presents illustrative examples of where new diagnostic platforms and technologies have been applied to this intriguing spectrum of diseases.

Chronic pulmonary aspergillosis: rationale and clinical guidelines for diagnosis and management

Chronic pulmonary aspergillosis (CPA) is an uncommon and problematic pulmonary disease, complicating many other respiratory disorders, thought to affect ~240 000 people in Europe. The most common form of CPA is chronic cavitary pulmonary aspergillosis (CCPA), which untreated may progress to chronic fibrosing pulmonary aspergillosis. Less common manifestations include: Aspergillus nodule and single aspergilloma. All these entities are found in non-immunocompromised patients with prior or current lung disease. Subacute invasive pulmonary aspergillosis (formerly called chronic necrotising pulmonary aspergillosis) is a more rapidly progressive infection (<3 months) usually found in moderately immunocompromised patients, which should be managed as invasive aspergillosis. Few clinical guidelines have been previously proposed for either diagnosis or management of CPA. A group of experts convened to develop clinical, radiological and microbiological guidelines. The diagnosis of CPA requires a combination of characteristics: one or more cavities with or without a fungal ball present or nodules on thoracic imaging, direct evidence of Aspergillus infection (microscopy or culture from biopsy) or an immunological response to Aspergillus spp. and exclusion of alternative diagnoses, all present for at least 3 months. Aspergillus antibody (precipitins) is elevated in over 90% of patients. Surgical excision of simple aspergilloma is recommended, if technically possible, and preferably via video-assisted thoracic surgery technique. Long-term oral antifungal therapy is recommended for CCPA to improve overall health status and respiratory symptoms, arrest haemoptysis and prevent progression. Careful monitoring of azole serum concentrations, drug interactions and possible toxicities is recommended. Haemoptysis may be controlled with tranexamic acid and bronchial artery embolisation, rarely surgical resection, and may be a sign of therapeutic failure and/or antifungal resistance. Patients with single Aspergillus nodules only need antifungal therapy if not fully resected, but if multiple they may benefit from antifungal treatment, and require careful follow-up.

Evaluation of Serum Aspergillus-Specific Immunoglobulin A by Indirect ELISA for Diagnosis of Feline Upper Respiratory Tract Aspergillosis

Background

Serological tests for diagnosis of aspergillosis in immunocompetent humans and animals are based on Aspergillus‐specific IgG (As‐IgG). In humans with chronic pulmonary aspergillosis, As‐IgA may be detectable even if IgG titers are negative. Cats with upper respiratory tract aspergillosis (URTA) have detectable As‐IgG, but their ability to mount an IgA response and its diagnostic utility are unknown.

Objectives

To determine whether serum As‐IgA can be detected in cats with URTA and evaluate its diagnostic utility alone or combined with As‐IgG.

Animals

Twenty‐three cats with URTA (Group 1), 32 cats with other respiratory diseases (Group 2), and 84 nonrespiratory controls (Group 3).

Methods

Serum As‐IgA and As‐IgG was measured by indirect ELISA. Optimal cutoff values were determined by receiver‐operating curve analysis. Sensitivity (Se) and specificity (Sp) for URTA diagnosis were determined.

Results

Serum IgA was detected in 91.3% of Group 1 cats. The Se of IgA detection was 78.3% and Sp was 96.9% for Group 2, 85.7% for Group 3 and 88.8% for Group 2 and 3 combined. Assay Se for IgG was 100% and Sp was 92.2%. Using combined IgA and IgG results at cutoffs optimized for Sp for IgA and Se for IgG and combined controls (Groups 2 and 3), Se for diagnosis was 100% and Sp was 91.4%.

Conclusion and Clinical Importance

Most cats with URTA have serum As‐IgA antibodies that can be detected by ELISA. Paired measurement of serum As‐IgA and IgG shows no benefit for diagnosis of feline URTA over IgG alone.

Acute invasive pulmonary aspergillosis, shortly after occupational exposure to polluted muddy water, in a previously healthy subject

Invasive pulmonary aspergillosis (IPA) predominantly occurs in severely neutropenic immunocompromised subjects. The occurrence of acute IPA after brief but massive exposure to Aspergillus conidia in previously healthy subjects has been documented, although only six such cases have been reported. The diagnosis was delayed in all six of the affected patients, five of whom died. We report the case of a 50-year-old HIV-negative male, a water pipeline maintenance worker, who presented with acute-onset dyspnea and fever one day after working for 2 h in a deep pit containing polluted, muddy water. Over a one-month period, his general condition deteriorated markedly, despite antibiotic therapy. Imaging showed bilateral diffuse nodules with cavitation, some of which were surrounded by ground-glass opacity suggestive of a halo sign (a hallmark of IPA). Cultures (of sputum/bronchial aspirate samples) and serology were positive for Aspergillus fumigatus. After being started on itraconazole, the patient improved. We conclude that massive exposure to Aspergillus conidia can lead to acute IPA in immunocompetent subjects.

Practice Guidelines for the Diagnosis and Management of Aspergillosis: 2016 Update by the Infectious Diseases Society of America

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.

Chronic Pulmonary Aspergillosis-Where Are We? and Where Are We Going?

Chronic pulmonary aspergillosis (CPA) is estimated to affect 3 million people worldwide making it an under recognised, but significant health problem across the globe, conferring significant morbidity and mortality. With variable disease forms, high levels of associated respiratory co-morbidity, limited therapeutic options and prolonged treatment strategies, CPA is a challenging disease for both patients and healthcare professionals. CPA can mimic smear-negative tuberculosis (TB), pulmonary histoplasmosis or coccidioidomycosis. Cultures for Aspergillus are usually negative, however, the detection of Aspergillus IgG is a simple and sensitive test widely used in diagnosis. When a fungal ball/aspergilloma is visible radiologically, the diagnosis has been made late. Sometimes weight loss and fatigue are predominant symptoms; pyrexia is rare. Despite the efforts of the mycology community, and significant strides being taken in optimising the care of these patients, much remains to be learnt about this patient population, the disease itself and the best use of available therapies, with the development of new therapies being a key priority. Here, current knowledge and practices are reviewed, and areas of research priority highlighted.

Allergic Bronchopulmonary Aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA), a progressive fungal allergic lung disease, is a common complication of asthma or cystic fibrosis. Although ABPA has been recognized since the 1950s, recent research has underscored the importance of Th2 immune deviation and granulocyte activation in its pathogenesis. There is also strong evidence of widespread under-diagnosis due to the complexity and lack of standardization of diagnostic criteria. Treatment has long focused on downregulation of the inflammatory response with prolonged courses of oral glucocorticosteroids, but more recently concerns with steroid toxicity and availability of new treatment modalities has led to trials of oral azoles, inhaled amphotericin, pulse intravenous steroids, and subcutaneously-injected anti-IgE monoclonal antibody omalizumab, all of which show evidence of efficacy and reduced toxicity.

Prospective Evaluation of a New Aspergillus IgG Enzyme Immunoassay Kit for Diagnosis of Chronic and Allergic Pulmonary Aspergillosis

Anti-Aspergillus IgG antibodies are important biomarkers for the diagnosis of chronic pulmonary aspergillosis (CPA) and allergic bronchopulmonary aspergillosis (ABPA). We compared the performance of a new commercial enzyme immunoassay (EIA) (Bordier Affinity Products) with that of the Bio-Rad and Virion\Serion EIAs. This assay is novel in its association of two recombinant antigens with somatic and metabolic antigens of Aspergillus fumigatus In a prospective multicenter study, 436 serum samples from 147 patients diagnosed with CPA (136 samples/104 patients) or ABPA (94 samples/43 patients) and from 205 controls (206 samples) were tested. We obtained sensitivities of 97%, 91.7%, and 86.1%, and specificities of 90.3%, 91.3%, and 81.5% for the Bordier, Bio-Rad, and Virion\Serion tests, respectively. The Bordier kit was more sensitive than the Bio-Rad kit (P < 0.01), which was itself more sensitive than the Virion\Serion kit (P = 0.04). The Bordier and Bio-Rad kits had similar specificity (P = 0.8), both higher than that of the Virion\Serion kit (P = 0.02). The area under the receiver operating characteristic (ROC) curves confirmed the superiority of the Bordier kit over the Bio-Rad and the Virion\Serion kits (0.977, 0.951, and 0.897, respectively; P < 0.01 for each comparison). In a subset analysis of 279 serum samples tested with the Bordier and Bio-Rad kits and an in-house immunoprecipitin assay (IPD), the Bordier kit had the highest sensitivity (97.7%), but the IPD tended to be more specific (71.2 and 84.7%, respectively; P = 0.10). The use of recombinant, somatic, and metabolic antigens in a single EIA improved the balance of sensitivity and specificity, resulting in an assay highly suitable for use in the diagnosis of chronic and allergic aspergillosis.

Comparison of six Aspergillus-specific IgG assays for the diagnosis of chronic pulmonary aspergillosis (CPA)

OBJECTIVES

Chronic pulmonary aspergillosis (CPA) is estimated to affect 3 million persons worldwide. Aspergillus-specific IgG is a key component in CPA diagnosis. We aimed to establish the optimal diagnostic cut offs for CPA and the comparative performance of six assays in this context.

METHODS

Sera from 241 patients with CPA and 100 healthy blood donors were tested using five Aspergillus-specific IgG assays plus precipitin testing using Microgen Aspergillus antigens.

RESULTS

Receiver operating characteristic (ROC) curve area under the curve (AUC) results were as follows: ThermoFisher Scientific ImmunoCAP 0.996 (95% confidence interval 0.992-1), Siemens Immulite 0.991 (0.982-1), Serion 0.973 (0.960-0.987), Dynamiker 0.918 (0.89-0.946) and Genesis 0.902 (0.871-0.933). Optimal CPA diagnostic cut-offs were; ImmunoCAP 20 mg/L (96% sensitivity, 98% specificity), Immulite 10 mg/L (96% sensitivity, 98% specificity), Serion 35 U/ml (90% sensitivity, 98% specificity), Dynamiker 65 AU/ml (77% sensitivity, 97% specificity) and Genesis 20 U/ml (75% sensitivity, 99% specificity). The precipitin test was 59% sensitive and 100% specific.

CONCLUSIONS

ImmunoCAP and Immulite were statistically significantly superior to the other assays. Precipitins testing performed poorly. The currently accepted ImmunoCAP cut-off of 40 mg/L appears sub-optimal for CPA diagnosis and may require revision in this context.