A Proteomic Approach for Identifying Proteins that Accumulate During Storage of Red Cell Products

The aim of this project was to identify potential protein mediators of adverse transfusion reactions in stored red cell concentrates. Previously, research into protein mediators of adverse transfusion reactions has focussed on specific proteins, such as cytokines. In this study, a global approach was taken which involved two-dimensional electrophoresis based Proteomics, which has the potential to uncover previously unrecognised mediators or novel proteins. Red cell products with and without pre-storage leukoreduction (each n = 6) were prepared and stored according to standard blood bank procedures. Supernatant samples were taken at several time points until product expiry. Proteins were separated by two-dimensional electrophoresis and those that accumulated in the supernatant were selected for identification by mass spectrometry. The protein profile of supernatant from leukoreduced red cell products was less complex compared to non-leukoreduced products (from 4.4 fold fewer proteins at day 1 to 1.6 fold fewer at day 43). Several proteins were observed to be predominantly present in leukoreduced products which may potentially be beneficial to red cell survival. These proteins were identified as being involved in the maintenance of a stable extracellular environment. Conversely, a number of proteins, which may have detrimental effects, were predominantly expressed in non-leukoreduced products. These proteins included a neutrophil chemoattractant (activator) and a potential acute-phase reactant. A number of proteins identified by mass spectrometry were matched to theoretical proteins of unknown function. The findings confirm the usefulness of Proteomics to investigate storage effects on blood products. The clinical relevance of these proteins is the focus of our future investigations.