Galactose IgE Galactose-alpha-1,3 Alpha-Gal
Galactose-alpha-1,3-galactose, IgE; Beef, IgE; Pork, IgE; Lamb, IgE; Milk, IgE
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.
The presence of IgE antibodies against galactose-alpha-1,3-galactose (alpha-gal) is associated with red meat allergy.
Individuals with IgE antibodies against alpha-gal might develop anaphylactic reactions to the drug cetuximab.
For 1 allergen: 0.3 mL For more than 1 allergen: (0.05 mL x number of allergens) + 0.25 mL deadspace
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.
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.
Concentrations > or =0.70 Ku/L (Class 2 and above) will flag as abnormally high
For BEEF, PORK, LAMB, MILK:
Reference values apply to all ages.
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.