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Test ID MPSF Micropolyspora faeni, IgG Antibodies, Serum

Reporting Name

Micropolyspora faeni, IgG Ab, S

Useful For

Evaluation of patients suspected of having hypersensitivity pneumonitis induced by exposure to Micropolyspora faeni

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type


Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Reference Values

0-12 years: ≤4.9 mg/L

13-18 years: ≤9.1 mg/L

>18 years: ≤13.2 mg/L

Day(s) and Time(s) Performed

Monday through Friday; 4 p.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
MPSF Micropolyspora faeni, IgG Ab, S 26948-0


Result ID Test Result Name Result LOINC Value
MPSF Micropolyspora faeni, IgG Ab, S 26948-0

Clinical Information

Micropolyspora faeni is one of the causative agents of hypersensitivity pneumonitis (HP). Other causative microorganisms include Thermoactinomyces vulgaris and Aspergillus fumigatus. The development of HP caused by Micropolyspora faeni is accompanied by an immune response to Micropolyspora faeni antigens with production of IgG antibodies. While the immunopathogenesis of HP is not known, several immune mechanisms are postulated to play a role, including both cellular and humoral mechanisms.(1)


Elevated concentrations of IgG antibodies to Micropolyspora faeni, Thermoactinomyces vulgaris, or Aspergillus fumigatus in patients with signs and symptoms of hypersensitivity pneumonitis may be consistent with disease caused by exposure to 1 or more of these organic antigens.


IgG antibodies to Micropolyspora faeni, Thermoactinomyces vulgaris, or Aspergillus fumigatus may be found in sera from healthy individuals; the presence of these specific antibodies is not sufficient to establish the diagnosis of hypersensitivity pneumonitis (HP).


The concentrations of antibodies to these antigens may decrease following treatment, although elevated concentrations may persist in treated patients.

Clinical Reference

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, MO, Mosby-Year Book Inc., 1998

2. Girard M, Lacasse Y, Cormier Y: Hypersensitivity pneumonitis. Allergy 2009;64:322-334

3. Grunes D, Beasley MB: Hypersensitivity pneumonitis: A review and update of histologic findings. J Clin Pathol 2013;66:888-895

Analytic Time

Same day/1 day

Reject Due To


Mild OK; Gross OK


Mild OK; Gross OK





NY State Approved


Method Name

Fluorescence Enzyme Immunoassay (FEIA)

Secondary ID