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Test Code ALGAL Galactose-Alpha-1,3-Galactose (Alpha-Gal), IgE, Serum


Ordering Guidance


For a listing of allergens available for testing, see Allergens - Immunoglobulin E (IgE) Antibodies.



Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL for every 5 allergens requested

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Useful For

As an aid in diagnosis of an IgE mediated hypersensitivity allergy to non-primate mammalian red meat, such as beef, pork, venison, and meat-derived products (eg, gelatin)

 

This test is not useful in patients previously treated with immunotherapy to determine if residual clinical sensitivity exists.

 

This test is not useful for patients in whom the medical management does not depend upon identification of allergen specificity.

Testing Algorithm

Other meat allergen IgE antibody tests may be considered in addition to galactose-alpha-1,3-galactose IgE antibody testing in cases of suspected red meat allergy.

Method Name

Fluorescence Enzyme Immunoassay (FEIA)

Reporting Name

Galactose-alpha-1,3-galactose, IgE

Specimen Type

Serum

Specimen Minimum Volume

For 1 allergen: 0.3 mL
For more than 1 allergen: (0.05 mL x number of allergens) + 0.25 mL deadspace

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days
  Frozen  90 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK

Clinical Information

Immunoglobulin E antibodies to galactose-alpha-1,3-galactose (alpha-gal), a carbohydrate commonly expressed on non-primate mammalian proteins, are capable of eliciting allergenic reactions.

 

Sensitization may occur through tick bites or exposure to the drug cetuximab. In the United States, individuals bitten by Amblyomma americanum, also known as the Lone Star tick, may develop IgE antibodies to alpha-gal, although sensitization to alpha-gal through other tick species has also been implicated.(1) The Lone Star tick was historically localized to the southern and southeastern United States but has now expanded its range into the central Midwest and northwards along the eastern seaboard. It is thought to be responsible for most cases of alpha-gal sensitization in the United States. The tick species that appears to be responsible for these responses in France is Ixodes ricinus, while in Australia it is Ixodes holocyclus.(2,3,4)

 

Signs and symptoms of an alpha-gal allergic reaction are often delayed compared with other food allergies. Upon exposure of sensitized subjects to non-primate mammalian meat (eg, beef, pork, venison) or meat-derived product such as gelatin, a delayed allergic response may ensue, often 3 to 6 hours after ingestion. Symptoms can include urticaria, angioedema, difficulty breathing, abdominal pain, vomiting, and even anaphylactic shock.

 

Individuals who have antibodies produced against alpha-gal following a tick bite or previous exposure to the drug cetuximab may experience anaphylaxis when given cetuximab. Cetuximab is a monoclonal antibody, which contains an alpha-gal epitope on the antigen binding fragment (Fab fragment) of the monoclonal drug. Unlike the delayed onset anaphylaxis associated with red meat consumption, individuals with IgE antibody response to alpha-gal can experience immediate onset anaphylaxis upon intravenous cetuximab administration.

 

Although most sensitizations to alpha-gal occur later in life, children who develop IgE antibodies to alpha-gal may also experience anaphylaxis and urticaria 3 to 6 hours after eating mammalian meat. Unlike their adult counterparts, who frequently present with anaphylaxis, the majority of children with this syndrome present with urticaria. Alpha-gal can also be found in mammalian milk, including cow and goat milk.

 

In vitro serum testing for IgE antibodies provides an indication of the immune response to allergens that may be associated with allergic disease.

Reference Values

Class

IgE kU/L

Interpretation

0

<0.10

Negative

0/1

0.10-0.34

Borderline/equivocal

1

0.35-0.69

Equivocal

2

0.70-3.49

Positive

3

3.50-17.4

Positive

4

17.5-49.9

Strongly positive

5

50.0-99.9

Strongly positive

6

≥100

Strongly positive

 

Concentrations of 0.70 Ku/L or more (Class 2 and above) will flag as abnormally high

Reference values apply to all ages.

Interpretation

Detection of IgE antibodies in serum (class 1 or greater) indicates an increased likelihood of allergic disease as opposed to other etiologies and defines the allergens that may be responsible for eliciting signs and symptoms.

 

The level of IgE antibodies in serum varies directly with the concentration of IgE antibodies expressed as a class score or kU/L.

Cautions

Some individuals with clinically insignificant sensitivity to allergens may have measurable levels of IgE antibodies in serum, and results must be interpreted in the clinical context.

 

False-positive results for IgE antibodies may occur in patients with markedly elevated serum IgE (>2500 kU/L) due to nonspecific binding to allergen solid phases.

Day(s) Performed

Monday through Friday

Report Available

Same day/1 to 3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

86008

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ALGAL Galactose-alpha-1,3-galactose, IgE 73837-7

 

Result ID Test Result Name Result LOINC Value
ALGAL Galactose-alpha-1,3-galactose, IgE 73837-7

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Allergen Test Request (T236)

-Microbiology Test Request (T244)