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Test Catalog

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

Useful For Suggests clinical disorders or settings where the test may be helpful

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.

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

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.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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 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.

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

> or =100

Strongly positive

Concentrations > or =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

> or =100

Strongly positive

Reference values apply to all ages.

Interpretation Provides information to assist in interpretation of the test results

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 Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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.

Clinical Reference Recommendations for in-depth reading of a clinical nature

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

Special Instructions Library of PDFs including pertinent information and forms related to the test