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Test ID APGAL Galactose-Alpha-1,3-Galactose (Alpha-Gal) Mammalian Meat Allergy Profile, Serum


Advisory Information


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



Specimen Required


Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 1.5 mL


Useful For

As an aid in diagnosis of an IgE mediated hypersensitivity allergy to non-primate mammalian red meat or meat-derived products, such as beef, pork, venison, and meat-derived products such as gelatin via allergen profile testing

 

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.

Profile Information

Test ID Reporting Name Available Separately Always Performed
ALGAL Galactose-alpha-1,3-galactose, IgE Yes Yes
BEEF Beef, IgE Yes Yes
PORK Pork, IgE Yes Yes
LAMB Lamb, IgE Yes Yes
MILK Milk, IgE Yes Yes

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

Alpha-Gal Panel, S

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

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 both 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

Galactose-Alpha-1,3-Galactose:

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 ≥0.70 Ku/L (Class 2 and above) will flag as abnormally high


For BEEF, PORK, LAMB, MILK:

Class

IgE kUa/L

Interpretation

0

<0.35

Negative

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

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.

Clinical Reference

1. Berg EA, Platts-Mills TAE, Commins SP: Drug allergens and food--the cetuximab and galactose-alpha-1,3-galactose story. Ann Allergy Asthma Immunol. 2014 Feb;112(2):97-101

2. Commins SP, Platts-Mills TAE: Delayed anaphylaxis to red meat in patients with IgE Specific for Galactose alpha-1,3-Galactose (alpha-gal). Curr Allergy Asthma Rep. 2013 Feb;13(1):72-77

3. Commins SP, James HR, Kelly LA, et al: The relevance of tick bites to the production of IgE antibodies to the mammalian oligosaccharide galactose-alpha-1,3-galactose. J Allergy Clin Immunol. 2011 May;127(5):1286-1293

4. Wolver SE, Sun DR, Commins SP, Schwartz LB: A peculiar cause of anaphylaxis: no more steak? The journey to discovery of a newly recognized allergy to galactose-alpha-1,3-galactose found in mammalian meat. J Gen Intern Med. 2013 Feb;28(2):322-325

5. Commins SP, Platts-Mills TAE: Tick bites and red meat allergy. Curr Opin Allergy Clin Immunol. 2013 Aug;13(4):354-359

6. Hamsten C, Starkhammar M, Tran TA, et al: Identification of galactose-alpha-1,3-galactose in the gastrointestinal tract of the tick Ixodes ricinus; possible relationship with red meat allergy. Allergy. 2013 Apr;68(4):549-552

7. Steinke JW, Platts-Mills TAE, Commins SP: The alpha-gal story: lessons learned from connecting the dots. J Allergy Clin Immunol. 2015 Mar;135(3):589-597

8. Crispell G, Commins SP, Archer-Hartman SA, Choudhary S, Dharmarajan G, Azadi P, Karim S: Discovery of alpha-gal-containing antigens in North American tick species believed to induce red meat allergy. Front Immunol. 2019 May 17;10:1056

9. Homburger HA, Hamilton RG: Allergic diseases. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed.  Elsevier; 2017:1057-1070

Day(s) and Time(s) Performed

Monday through Friday; 9 a.m.-8 p.m.

Saturday; 8 a.m.-3 p.m.

Analytic Time

Same day/1 day

Test Classification

This test has been cleared, approved or is exempt by the U.S. 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

86003 x 5

LOINC Code Information

Test ID Test Order Name Order LOINC Value
APGAL Alpha-Gal Panel, S In Process

 

Result ID Test Result Name Result LOINC Value
BEEF Beef, IgE 6039-2
LAMB Lamb, IgE 6155-6
MILK Milk, IgE 6174-7
PORK Pork, IgE 6219-0
ALGAL Galactose-alpha-1,3-galactose, IgE 73837-7