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Allergen Profile, Milk, IgE With Component Reflexes
Milk; Reflex criteria: If milk IgE ≥0.35 kU/L, α-lactalbumin, β-lactoglobulin, and casein IgE will be performed.
The measurement of specific immunoglobulin E (IgE) to individual components of an allergen, either purified native or recombinant, is referred to as component resolved diagnosis (CRD).1-4 This approach represents an improvement over traditional measurement of IgE to allergen extracts that contain a mixture of proteins. The pattern of specific IgE reactivity to component allergens can predict which patients are at higher risk for systemic allergic reactions versus those who are sensitized but clinically tolerant. CDR can also be used to predict which patients are at risk for more severe reactions and which patients are likely to have milder symptoms.
Allergen-specific IgE assays do not demonstrate absolute positive and negative predictive values for allergic disease. Clinical history must be incorporated into the diagnostic determination. Although the use of component resolved IgE testing may enhance the evaluation of potentially allergic individuals over the use of whole extracts alone, it cannot yet replace clinical history and oral food challenge in most cases. Sensitization against thus far unidentified determinants that are not found in the whole extract or in components might cause symptoms in rare cases.
Thermo Fisher ImmunoCAP® Allergen-specific IgE
Cow's milk allergy is the most common food allergy in early childhood and affects about 2.5% of infants during their first years of life5-7 with symptoms ranging from relatively mild to severe and life-threatening.8 Egg allergy can cause severe allergic reactions in sensitized children, and egg avoidance can cause significant dietary limitations. Although most infants outgrow cow’s milk allergy by age three, it can become persistent in a minority of children. Cow’s milk allergy is associated with an increased risk of development of other allergic disorders, such as allergic asthma, atopic eczema, rhinoconjunctivitis, or egg allergy.9
Approximately 75% of children with cow’s milk allergy react to fresh milk and tolerate extensively heated cow’s milk.10
Cow's Milk Components
• 80% of the milk protein content is casein (Bos d 8).11
• Bos d 8 is relatively stable to heat and retains its allergenicity after extensive heating.10,11
• The levels of Bos d 8 IgE antibodies reflect the severity of the milk allergy.12-15
• High levels of Bos d 8 IgE antibodies indicate allergy to both fresh and baked milk.16
• Low or undetectable levels of Bos d 8 IgE antibodies indicate tolerance to baked milk products, eg, cakes and cookies.16
• Patients sensitized to Bos d 8 are also at risk of severe reactions upon intake of nondairy products in which casein may be used as an additive (eg, in sausages, chocolate, and potato chips).17,18
• Children often outgrow their milk allergy—early signs of tolerance development can be detected by tracking the reduction in cow’s milk IgE (extract)19,20 and/or the component Bos d 8 IgE levels over time.15,21-23
• Quantifying IgE levels to Bos d 8 can help determine if a challenge test should be performed.24-26
• Whey proteins make up twenty percent of the protein in milk.11 Whey proteins include α–lactalbumin (Bos d 4) and β–lactoglobulin (Bos d 5)11
• Whey proteins Bos d 4 and Bos d 5 are rather heat labile and, therefore, destroyed by cooking.11
• Patients sensitized to Bos d 4 and Bos d 5 but with low levels of IgE to Bos d 8 may tolerate baked milk products.12,15,27,28
• As tolerance develops, decreasing levels of IgE to Bos d 4 and Bos d 5 are also often observed.21
0.5 mL (Note: This volume does not allow for repeat testing.)