Development and stability of an in-house reference for blomia tropicalis allergen extract

Methods Standardized allergen extract of Blomia tropicalis was manufactured by BIOCEN (Cuba). The batch selected for IHR was characterized by in-vitro allergenic activity compared to the previous IHR, using ELISA-IgE-inhibition assays, with a pool of sera from patients allergic to Blomia tropicalis. Allergenic and protein composition was determined by Western-Blotting-IgE and SDS-PAGE. As final criterion allergenic activity was measured by in-vivo Skin Prick Test in allergic patients by parallel application of three dilutions. Relative potency was calculated by the method of parallel lines. The activity was expressed in Biological Units (BU), which is related to the skin reaction size produced by Histamine 10 mg/mL. Stability was assessed by means of an accelerated study at 4 temperatures (-70°, 4°C, 37°C and 60°C) during one year, testing at 0, 3, 6, 9 and 12 months.