Total protein concentration and stability of Amb a 1 in glycerinated ragweed sublingual immunotherapy stored at room temperature and refrigerated cold temperature

Abstract Background Few studies have investigated optimal storage conditions or expiration dates for sublingual immunotherapy (SLIT) formulations prepared from glycerinated allergen extracts. Hypothesis/Objectives The objective of this study was to compare concentrations of short ragweed major allergen ( Amb a 1 ) and total protein in SLIT formulations stored at two different temperatures. It was hypothesised that protein concentrations would show greater decline over time in a formulation stored at room temperature (RT) than in one stored under refrigeration. Materials and Methods Two SLIT samples containing equal volumes of 20,000 PNU Amb a 1 extract were prepared and stored at refrigerated cold (CT) (2–8°C) or RT (20–24°C) for 140 days. Changes in total protein and major allergen concentration and composition were measured by Bradford assay, two‐site enzyme‐linked immunosorbent assay and SDS–PAGE. Presence of Amb a 1 was confirmed with Western immunoblot. Data were analysed using an analysis of covariance, with p < 0.05 considered significant. Results SDS–PAGE showed compositional changes in a ~26–30 kDa protein band under RT and not CT storage. The Amb a 1 concentration of the RT SLIT sample declined significantly over time, compared to that of the CT SLIT sample ( F (1,8) = 47.69, p < 0.0001). There was no significant difference in total protein concentration over time between groups ( F (1,8) = 1.79, p = 0.22). Conclusions and Clinical Relevance These results demonstrate that storage of glycerinated SLIT formulations in refrigerated CT preserved the highest concentration of the specific allergen Amb a 1 , suggesting that SLIT formulations containing short ragweed should be stored under refrigeration.