Preparation of chemically stable allergen-specific sublingual immunotherapy from Egyptian allergens

Abstract

Background: The term "allergen extracts" refers to solutions of proteins or glycoproteins extracted from source raw materials.

Objectives: This study was planned to prepare chemically stable sublingual immunotherapy from different allergens in Egypt.

Methods: Allergen extraction from raw materials. The concentrated aqueous extract of each allergen was mixed with an equal volume of glycerol. The protein content of the preparations was determined using the modified Lowry assay method. The prepared allergens were stored for 9 months at 2-4°C. Samples were analyzed periodically (0, 3, 6, and 9 months of intervals) adopting the Lowry Assay method. Levels of specific IgE to Chenopodium album antigens were measured in patients' sera by ELISA.

Results: The concentration of all prepared allergens, as indicated by the concentration of the protein content, was found to decrease exponentially with time, implying first-order kinetics of degradation. From the values of the slopes of the log plot for each allergen, the half-life time (t_1/2 ) and (t_1/4 ) values were calculated. The expiration date was considered as the time after which the allergen loses 25% of its potency. The obtained values of t_1/4% vary according to the type of vaccine. The most stable one is that of Chenopodium album pollens (2.4 years) and the least stable is that of house dust Mites (9 months). The immunological characters of Chenopodium album extract were stable for at least 6 months.

Conclusion: Differences exist among allergen extracts made by multiple manufacturers. So, developments in studies on allergen preparation and characterization in a different locality are necessary.

Keywords: Egyptian environment; Lowry assay; allergen extract; chemical stability; sublingual immunotherapy.