© 2007 American Thoracic Society
Specific IgE against Recombinant Allergens in Allergic Bronchopulmonary AspergillosisTo the Editor:Kraemer and coworkers in their recent article made use of recombinant Aspergillus fumigatus (rAsp f) allergens in studying the effect of allergic bronchopulmonary aspergillosis (ABPA) on lung function in children with cystic fibrosis (1). In the literature there is some evidence that rAsp f allergens can be useful for elucidating the diagnosis of ABPA in patients with cystic fibrosis, through their use in serum IgE detection (2) or an intracutaneous test (3). However, data are not uniform, and further studies with larger numbers of patients remain necessary (4, 5). The evidence for the utility of these recombinant allergens in the diagnosis of ABPA in patients with asthma is much more scant. We performed an observational, cross-sectional study in 65 patients with asthma (40 women and 25 men) sensitized to Asp f as determined by immediate-reading skin tests (percutaneous or intradermal). Ages ranged from 12 to 81 years (mean, 44.7 yr; SD, 15.83 yr). Serum IgE specific for Asp f (IgEm3) was detected in 40% of patients, with different levels of antibodies for each patient. Serum titers of IgE against rAsp f1, f2, f3, f4, and f6 were determined. Only 19 of these 65 patients had IgE against at least one recombinant. ABPA was diagnosed by classical criteria (6) in six patients (9.2%). The disease was excluded in 17 (26%), but remained suspected in 42 (64.6%) of the patients sensitized to Asp f. Of the six patients in the diagnosed ABPA subgroup, only two showed serum IgE specific for the recombinant allergens. One of the patients showed different levels (classes I to IV) of these antibodies against the five allergens tested, whereas one showed antibodies only against rAsp f3 (class I). In our study, the investigation of specific IgE for the recombinant allergens, which could constitute a tool for both the detection of sensitization to Asp f and for the diagnosis of ABPA, showed no advantage over the use of natural Asp f antigens. The investigation of serum-specific IgE for recombinant allergens was not efficacious in diagnosing most of the patients in whom ABPA was diagnosed using the traditional criteria. The lack of standardization of the allergens used in the diagnosis of ABPA, which affects the reproducibility of results, could not be overcome by using recombinant. Asp f allergens, detection of ABPA disease, and making diagnosis more uniform across different health care facilities remains a challenge.
University of São Paulo, São Paulo, Brazil FOOTNOTES Conflict of Interest Statement: None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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