Thermoactinomyces vulgaris, IgG Antibodies, Serum
Evaluating patients suspected of having hypersensitivity pneumonitis induced by exposure to this antigen
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Thermoactinomyces vulgaris is a causative agent of hypersensitivity pneumonitis (HP). Other causative microorganisms include Micropolyspora faeni and Aspergillus fumigatus. While the immunopathogenesis of HP is not known, several immune mechanisms are postulated to play a role, including both cellular and humoral mechanisms.(1)
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.
0-12 years: < or =6.6 mg/L
13-18 years: < or =11.0 mg/L
>18 years: < or =23.9 mg/L
Elevated concentrations of IgG antibodies to Thermoactinomyces vulgaris are consistent with the diagnosis of hypersensitivity pneumonitis (HP) caused by exposure to this antigen.
Elevated concentrations of IgG antibodies to Thermoactinomyces vulgaris were found in a small number of sera from patients with HP (4%).(2)
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
IgG antibodies to Thermoactinomyces vulgaris are detectable in healthy individuals, and the presence of antibodies is not sufficient to establish the diagnosis of hypersensitivity pneumonitis (HP) caused by exposure to this antigen.
The levels of antibodies decrease following successful treatment of HP; but, elevated levels may persist for long periods.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Fink JN, Zacharisen MC: Chapter 19: Hypersensitivity pneumonitis. In Allergy Principles and Practice. Vol 1. Fifth edition. Edited by E Middleton Jr, CE Reed, EF Ellis, et al. St. Louis, MO, 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, CA, March 3-8, 2000. J Allergy Clin Immunol 2000;105:S304