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HelpTest Code ASPER Aspergillus fumigatus, IgG Antibodies, Serum
Additional Codes
| Mayo Test ID |
|---|
| SASP |
Reporting Name
Aspergillus fumigatus, IgG Ab, SUseful For
Evaluation of patients suspected of having hypersensitivity pneumonitis (HP) induced by exposure to Aspergillus fumigatus
Evaluation of patients suspected of having HP who have documented environmental exposures to high-humidity environments
Method Name
Fluorescence Enzyme Immunoassay (FEIA)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 21 days | |
| Frozen | 21 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | Reject |
Reference Values
<4 years: not established
≥4 years: ≤102 mg/L
Day(s) Performed
Monday through Friday
CPT Code Information
86606
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| SASP | Aspergillus fumigatus, IgG Ab, S | 26954-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| SASP | Aspergillus fumigatus, IgG Ab, S | 26954-8 |
Clinical Information
Hypersensitivity pneumonitis (HP) is a type of interstitial lung disease caused by an immune-mediated response to inhaled environmental antigens.(1) Patients with HP commonly display symptoms of cough, dyspnea, and midinspiratory squeaks. Patients may present with an acute onset of symptoms (within hours of antigen exposure) or a chronic onset (which may occur over a course of weeks to months). The nature of an individual’s disease course will be affected by several factors, including quantity of inhaled antigen, intensity/frequency of exposure, and genetic background. The epidemiology of HP is also challenging to understand, as incidence and prevalence of the disease varies with geographic areas, climate, and local customs. While the immunopathogenesis of HP is not completely understood, it is presumed to involve both type III and type IV hypersensitivity reactions, with the type III reaction characterized by the presence of IgG antibodies specific for the inciting antigen.
There are many antigens, both organic and inorganic, that have been associated with development of HP.(2) Causative organic antigens include a wide array of bacteria, mycobacteria, fungi, and animal proteins. Aspergillus fumigatus is a fungus found in locations with high humidity, including soil, greenhouses, and compost heaps. It is fairly ubiquitous and may even be found in household dust. Some individuals exposed to A fumigatus, particularly those individuals with routine exposure to high-humidity environments, may develop IgG antibodies against this antigen, which could lead to development of HP.
Clinical practice guidelines for HP include a diagnostic algorithm which focuses on exposure identification, imaging evaluation, and bronchoalveolar lavage/histopathology.(3) Detection of IgG antibodies specific for certain environmental antigens can help to document the causative exposure for an individual. This is critical, as an important treatment for these patients is antigen avoidance. However, IgG testing is only useful as supportive information for the diagnosis of HP; a positive result only indicates sensitization to the antigen and a negative result does not exclude the possibility that a patient with HP may be sensitized to another antigen.
Interpretation
Positive results for IgG antibodies to Aspergillus fumigatus, in patients with signs and symptoms of hypersensitivity pneumonitis, may be consistent with sensitization to this fungus.
Cautions
Positive results for IgG antibodies to Aspergillus fumigatus may be found in sera from healthy individuals who are sensitized to this fungus but do not display symptoms consistent with hypersensitivity pneumonitis (HP).
Negative results for IgG antibodies to A fumigatus do not exclude HP as a diagnosis; patients with clinical symptoms consistent with HP may be sensitized to a different antigen.
Elevated concentration of antibodies to A fumigatus may be also found in patients with invasive aspergillosis and cavitary lung disease.
Method Description
The Phadia ImmunoCAP System specific IgG fluorescent enzyme immunoassay provides an in vitro method for measuring the concentrations of circulating specific IgG antibodies in human blood samples. Specific IgG from the patient's serum reacts with the antigen of interest, which is covalently coupled to an ImmunoCAP. After washing away nonspecific IgG, enzyme-labeled anti-IgG antibodies are added to form a complex. After incubation, unbound enzyme-anti IgG is washed away, and the bound complex is then incubated with a developing agent. After stopping the reaction, the fluorescence of the eluate is measured. The fluorescence is proportional to the amount of specific IgG, which is present in the patient's sample, ie, the higher the fluorescence value, the more specific IgG antibody is present.(Package insert: ImmunoCAP Aspergillus. Phadia AB; 10/2019)