Received on January 26, 2006
Accepted on June 23, 2006

Clinical Immunology

Quantification of IgG Antibodies to Aspergillus fumigatus and Pigeon Antigens by ImmunoCAP Technology: An Alternative to the Precipitation Technique?

¹ Department of Laboratory Medicine, Immunology, University Hospital Leuven, Belgium
² Department of Internal Medicine, Pneumology, University Hospital Leuven, Belgium

^* To whom correspondence should be addressed. E-mail: erna.vanhoeyveld{at}uz.kuleuven.ac.be.

Background: We evaluated the ImmunoCAP technique for measurement of IgG specific to Aspergillus fumigatus and pigeon antigens.

Methods: We used ImmunoCAP and precipitation techniques to measure concentrations of IgG to A. fumigatus or pigeon antigens in sera from 265 patients and 42 controls. We also evaluated linearity, interference, imprecision, concordance, and diagnostic accuracy of the measuring techniques.

Results: The precipitation and ImmunoCAP technique showed moderate concordance (, 0.46 for both A. fumigatus and pigeon antibodies). Specific IgG results for A. fumigatus and pigeon were linear (r = 0.98 and 0.97, respectively), with interrun reproducibility rates of 23 and 14% and maximal interference of 36.5 and 8% by lipid and 24 and 21% by hemolysis, respectively. A. fumigatus antibody concentrations were higher in patients with aspergillosis and allergic bronchopulmonary aspergillosis (ABPA) (median, 103 and 70.1 mg_A/L, respectively) than in patients with other pulmonary diseases (median, 18.15-33.40 mg_A/L). Antibodies to pigeon antigens were high in patients with hypersensitivity pneumonitis (median, 1024 mg_A/L) and patients with other pulmonary diseases (median, 445 mg_A/L). Antibody titers were substantially higher in patients with other pulmonary diseases and contact with pigeons (median, 1060 mg_A/L) than in patients without antigen contact (median, 27.35 mg_A/L) (P <0.004).

Conclusions: Agreement between the precipitation and ImmunoCAP techniques was 86% for A. fumigatus and 70% for pigeon antigens. Highest concentrations of specific IgG to A. fumigatus were found in patients with aspergillosis and ABPA. Our results suggest that antigen contact was the most important variable affecting the presence of antibodies to pigeon antigen.