Aspergillus fumigatus, IgG Antibodies, Serum
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Aspergillus fumigatus is a causative agent of hypersensitivity pneumonitis (HP) as well as invasive lung disease with cavitation or pneumonitis, and allergic bronchopulmonary disease.(1) Other causative microorganisms of HP include Micropolyspora faeni, and Thermoactinomyces vulgaris. The development of HP and allergic bronchopulmonary disease caused by Aspergillus fumigatus is accompanied by an immune response to Aspergillus fumigatus antigen with production of IgG or IgE antibodies, respectively. While the immunopathogenesis of HP and allergic bronchopulmonary disease is not known, several immune mechanisms are postulated to play a role, including both cellular and humoral mechanisms.
Evaluating patients suspected of having lung disease caused by Aspergillus fumigatus
Elevated concentrations of IgG antibodies to Aspergillus fumigatus, Thermoactinomyces vulgaris, or Micropolyspora faeni in patients with signs and symptoms of hypersensitivity pneumonitis is consistent with disease caused by exposure to 1 or more of these organic antigens. Extreme elevations (>5 times the upper limit of normal) occur in some patients with active disease.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
IgG antibodies to Aspergillus fumigatus, Thermoactinomyces vulgaris, or Micropolyspora faeni are detectable in sera from healthy individuals, and the presence of antibodies is not sufficient to establish the diagnosis of hypersensitivity pneumonitis (HP).
Elevated concentrations of antibodies to Aspergillus fumigatus are found in patients with invasive aspergillosis and cavitary lung disease as well as HP.
The levels of antibodies to these antigens often decrease following treatment; but elevated levels may persist in treated patients for long periods.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
<4 years: not established
> or =4 years: < or =102 mg/L
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Fink JN, Zacharisen MC: Chapter 69: Hypersensitivity pneumonitis. In Allergy Principles and Practice. Vol 1. Fifth edition. Edited by E Middleton Jr, CE Reed, EF Ellis, et al. St. Louis, Mosby Year Book Inc, 1998
2. Anderson E, Jacob GL, Roberts GD, Homburger HA: Comparative evaluation of enzyme immunoassay and immunodiffusion for detection of IgG antibodies to hypersensitivity pneumonitis antigens. Poster Presentation, AAAAI Annual Meeting, San Diego, March 3-8, 2000. J Allergy Clin Immunol 2000;105:S304