Allergen Extract Preparation
ÎAllergen immunotherapy extract preparation should be performed by persons experienced and trained in handling allergenic products. A customized allergen immunotherapy extract should be prepared from a manufacturer's extract or extracts in accordance to the patient's clinical history and allergy test results and might contain single or multiple allergens. (D)
ÎAn allergen immunotherapy extract must be considered different if there is any change. There is potentially an increased risk of a systemic reaction if the immunotherapy extract is changed because of the possible variability in the composition and potency of allergen extracts. If the allergen immunotherapy extract is changed, the patient might need to be retested for specific IgE sensitivity and started on an immunotherapy formulation and schedule that is based on this re-evaluation. (D)
Principles of Mixing Allergen Immunotherapy
ÎConsideration of the following principles is necessary when mixing allergen extracts: (1) cross-reactivity of allergens, (2) optimization of the dose of each constituent, and (3) enzymatic degradation of allergens. (B)
Cross-reactivity of allergen extract
ÎThe selection of allergens for immunotherapy should be based in part on the cross-reactivity of clinically relevant allergens. Knowledge of allergen crossreactivity is important in the selection of allergens for immunotherapy because limiting the number of allergens in a treatment vial might be necessary to attain optimal therapeutic doses of each of the components. Many botanically related pollens contain allergens that are cross-reactive. When pollens are substantially cross-reactive, selection of a single pollen within the cross-reactive genus or subfamily might suffice. When pollen allergens are not substantially cross- reactive, testing for and treatment with multiple locally prevalent pollens might be necessary. (B)
Dose Selection
ÎThe efficacy of immunotherapy depends on achieving an optimal therapeutic dose of each of the constituents in the allergen immunotherapy extract. (A)
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