Comparison of Serum Markers for Allergic Bronchopulmonary Aspergillosis in Cystic Fibrosis
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Eur Respir J 2008; 31: 36–42 DOI: 10.1183/09031936.00078107 CopyrightßERS Journals Ltd 2008 Comparison of serum markers for allergic bronchopulmonary aspergillosis in cystic fibrosis P. Latzin*,#,", D. Hartl#,", N. Regamey*, U. Frey*, M.H. Schoeni* and C. Casaulta* ABSTRACT: The diagnosis of allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis AFFILIATIONS (CF) is a challenge. Thymus- and activation-regulated chemokine (TARC) has recently been *Division of Respiratory Medicine, Children’s University Hospital of reported to play a role in ABPA. The aim of this study was to compare the diagnostic value of Bern, Bern, Switzerland, TARC with that of known serological markers for diagnosis of ABPA in CF patients. #Children’s Hospital of the Ludwig The present study longitudinally followed 48 CF patients, of whom 12 had a diagnosis of ABPA Maximilian University of Munich, according to Nelson’s criteria, for 1–8 yrs with repeated measurements of serum total Munich, Germany. "Both authors contributed equally to immunoglobulin (Ig)E, specific Aspergillus fumigatus IgE and IgG, specific IgE against this article. recombinant A. fumigatus allergens (rAsp f) 1, 3, 4 and 6, and TARC. Median (interquartile range) TARC levels were 589 (465–673) pg?mL-1 in ABPA patients and 232 CORRESPONDENCE (189–289) pg?mL-1 in non-ABPA patients. Receiver operating characteristic curves revealed that P. Latzin Division of Respiratory Medicine TARC was superior to the other markers for diagnosis of ABPA. Diagnostic accuracy was greater Dept of Paediatrics for TARC (93%) than for total IgE (74%), or rAsp f 4 (75%) or f 6 (79%). University Children’s Hospital of Bern The present study indicates that thymus- and activation-regulated chemokine may be useful in Inselspital the diagnosis of allergic bronchopulmonary aspergillosis in cystic fibrosis patients. However, 3010 Bern Switzerland larger studies are needed before thymus- and activation-regulated chemokine can routinely be Fax: 41 316324807 used in diagnostic algorithms. E-mail: [email protected] KEYWORDS: Allergic bronchopulmonary aspergillosis, cystic fibrosis, diagnostic value, Received: June 26 2007 immunoglobulin E, serum marker, thymus- and activation-regulated chemokine Accepted after revision: September 11 2007 llergic bronchopulmonary aspergillosis lung colonisation with A. fumigatus occurs in SUPPORT STATEMENT (ABPA) is a pulmonary hypersensitivity 20–25% of CF patients [9–11]. Therefore, as This study was supported by a Swiss A disease mediated by an allergic response stated in the most recent consensus document National Foundation (Berne, to Aspergillus fumigatus [1]. ABPA occurs in ,10% on diagnosis and therapy of ABPA in CF Switzerland) grant 3200-B0-112099 to U. Frey, a grant from the German of cystic fibrosis (CF) patients and may lead to patients, serological findings should contribute Society for Paediatric Pneumology acute worsening of respiratory status and strongly to the confirmation or exclusion of (Hanover, Germany) to D. Hartl and a ongoing decline in lung function [2], ultimately clinically suspected ABPA [5]. grant from the Mu¨nchener progressing to a chronic state and lung fibrosis Medizinische Wochenschrift (Munich, Animal studies suggest a pathophysiological role without adequate treatment [3]. Despite the Germany) to P. Latzin. existence of the gold-standard Nelson criteria of the chemokine thymus- and activation-regu- [4], diagnosis of ABPA in CF patients remains lated chemokine (TARC) in ABPA by linking an STATEMENT OF INTEREST difficult [5]. The wide variation in diagnostic antifungal immune response with the promotion None declared. practices between clinics [6], different estimates of T-helper cell (Th) type 2-mediated hypersen- of prevalence and a delay in recognition lead to sitivity to A. fumigatus [12]. It has recently been undertreatment [7]. shown, in a cross-sectional study, that serum levels of TARC are elevated in CF patients with The main reason for the difficulties in diagnosis of ABPA [13]. However, longitudinal clinical data ABPA and ABPA exacerbations in CF patients is on the usefulness of this marker are lacking and the overlap of diagnostic criteria for ABPA with no further study has been performed validating common manifestations of CF. Pulmonary infil- TARC in comparison to other putative ABPA trates, obstructive lung disease and bronchiec- serum markers. The present study aimed to tasis occur regularly in CF patients, due to the answer the following questions. 1) Can the results European Respiratory Journal underlying disease with bacterial colonisation, and of the previously published cross-sectional study Print ISSN 0903-1936 thus are not specific to ABPA [8]. Furthermore, [13] be confirmed in another CF population? Online ISSN 1399-3003 36 VOLUME 31 NUMBER 1 EUROPEAN RESPIRATORY JOURNAL P. LATZIN ET AL. TARC AS SERUM MARKER FOR ABPA 2) What is the diagnostic value (sensitivity and specificity) of skin-prick testing, elevated total immunoglobulin (Ig)E levels TARC compared to other serological markers of ABPA? 3) Is (cut-off 500 IU?mL-1), increased levels of specific serum IgE TARC useful for the early detection of ABPA development? (cut-off 17.5 IU?mL-1) and IgG (cut-off 20 kU?L-1) directed against A. fumigatus [4]. METHODS Study design Serum markers From 1998 onwards, a group of 48 patients (23 females and 25 In the collected serum samples, the following parameters were males; median (interquartile range (IQR)) age 9 (7–14) yrs) measured: total IgE, specific IgE (radioallergosorbent test) to A. with CF were systematically followed longitudinally [14]. All fumigatus, specific IgG to A. fumigatus extract (ELISA) and patients underwent careful clinical assessment, lung function specific IgE against the recombinant A. fumigatus allergens testing and microbiological diagnosis at all visits during the (rAsp f) 1, 3, 4 and 6 [14, 15] and TARC. study period. Skin testing against A. fumigatus was routinely TARC levels were analysed in triplicate by sandwich ELISA performed using Bencard skin test antigens (SmithKline (R&D Systems, Minneapolis, MN, USA) according to the Beecham, Mu¨ nchenbuchsee, Switzerland). Chest radiography manufacturer’s instructions, and concentrations calculated from was performed on study entry and thereafter at least annually. standard curves with detection limits of 7–3,000 pg?mL-1. Intra- In addition, serum samples were collected at the study visits, assay variability was determined by evaluating five serum resulting in an average of six serum samples per patient for samples 10 times within the same assay run and showed a analysis (table 1). The Ethics Committee of Berne (Berne, coefficient of variation of 6–9%. Interassay variability was Switzerland) approved the study and written consent was determined by measuring five serum samples in five consecu- obtained on enrolment. tive assay runs and showed a coefficient of variation of 8–17%. Clinical diagnosis of ABPA Statistical analysis According to Nelson’s criteria, patients were diagnosed as Data are presented as median (IQR) unless otherwise having clinical ABPA when at least six out of the seven indicated. The diagnostic value of the serological markers following criteria were fulfilled: wheezing, positive A. fumiga- and receiver operator characteristic (ROC) curves were tus sputum culture, presence of defined infiltrates on chest calculated. Cut-off levels were set at the level that resulted in radiography, positive acute reaction to A. fumigatus on the optimal diagnostic accuracy, defined as correctly positively classified plus correctly negatively classified as a percentage of the total. TABLE 1 Patient data and results of serum measurements in cystic fibrosis patients with and without allergic Nested matched case–control analysis bronchopulmonary aspergillosis (ABPA) In order to assess whether TARC level elevation was specific to ABPA Non-ABPA ABPA or an epiphenomenon of the hypersensitivity against A. fumigatus in ABPA patients, a nested matched case–control analysis was performed and TARC levels compared between Patients 12 36 cases (ABPA patients) and controls (non-ABPA patients), Age at study entry yrs 10 (8–12) 9 (7–14) matched for total IgE and rAsp f 6 levels, respectively. Males/females 7/5 19/17 Study duration months 40 (35–80) 40 (27–55) RESULTS + + Serum samples 7 (4–12); 87 5 (1–8); 178 Of the 48 CF patients, 12 were diagnosed with clinical ABPA FEV1 on study entry % pred 73 (77–81) 89 (72–99) based on Nelson’s criteria. Nine patients were diagnosed with A. fumigatus in sputum# 12 20 # ABPA before study entry and three developed their first P. aeruginosa in sputum 12 34 episode of clinical ABPA during the study period; all were Serum measurements assigned to the ABPA group. The other 36 CF patients did not Total IgE IU?mL-1 965 (324–1961) 59 (21–433) -1 fulfil six out of seven of Nelson’s criteria for diagnosis at any Specific IgG to A. fumigatus kU?L 145 (66–244) 51 (17–105) time before or during the study period and were assigned to Specific IgE to A. fumigatus RAST class" 4 (3–5) 1 (0–3) -1 the non-ABPA group. Details of the patients’ characteristics are rAsp f 1 EU?mL 128 (60–364) 21 (6–59) given in table 1. rAsp f 3 EU?mL-1 253 (99–739) 37 (14–94) -1 rAsp f 4 EU?mL 23 (11–53) 4 (1–12) TARC compared to other serological markers for the -1 rAsp f 6 EU?mL 25 (8–67) 3 (2–8) diagnosis of ABPA -1 TARC pg?mL 589 (465–673) 232 (189–289) Median (IQR) TARC levels were 589 (465–673) pg?mL-1 in ABPA patients compared to 232 (189–289) pg?mL-1 in non- Data are presented as n or median (interquartile range) unless otherwise stated. ABPA patients (table 1). In the 16 non-ABPA patients with FEV1:forcedexpiratoryvolumeinonesecond;%pred:%predicted; neither sensitisation to A. fumigatus nor elevation of total IgE A. fumigatus: Aspergillus fumigatus; P. aeruginosa: Pseudomonas aeruginosa; levels, TARC levels were 207 (178–282) pg?mL-1.