The pro-inflammatory potential of microparticles in red blood cell units.

BACKGROUND: Microparticles (MPs) are submicron size cell fragments that are released from cells. OBJECTIVES: We hypothesise that MPs increase during red blood cell (RBC) storage and are part of the pro-inflammatory activity, which accumulates in the RBC supernatant. METHODS/MATERIALS: RBC units were separated from whole blood of eight healthy donors: 5 U were split, with 50% undergoing leucoreduction (LR) and the remaining left as unmodified controls. The remaining 3 U were leucoreduced. Samples were obtained at days (D) 1 and 42 and cell-free supernatants separated and stored. The supernatants were centrifuged at 17 000 × g (60 min) or 100 000 × g (120 min) into microparticle-rich (MPR) and microparticle-poor (MPP) portions, resuspended in albumin, incubated with antibodies to CD235 (RBCs), CD45 [white blood cells (WBCs)] and CD41a [platelets (Plts)], and analysed by flow cytometry. Isolated neutrophils were incubated with these samples, and priming activity measured. RESULTS: Total MPs increased during storage; however, MPs that marked for precursor cell types did not. Significant priming accumulated in the MPP fraction during storage with some activity present in the MPR fraction from D1 and D42 LR-RBCs. CONCLUSION: Most of the pro-inflammatory priming activity from stored RBCs resides in the MPP supernatant, although the MPR fraction from D42 LR-RBCs does contain some priming activity.

Proteomic analysis of the supernatant of red blood cell units: the effects of storage and leucoreduction.

BACKGROUND: Red blood cell (RBC) transfusion is a life-saving intervention for critically ill patients; however, it has been linked to increased morbidity and mortality. We hypothesize that a number of important proteins accumulate during routine storage of RBCs, which may explain some of the adverse effects seen in transfused patients. STUDY DESIGN: Five RBC units were drawn and divided (half prestorage leucoreduced (LR-RBC) and half left as an unmodified control (RBC). The supernatant was separated on days 1 and 42 of storage and proteomic analyses completed with in-gel tryptic digestion and nano-liquid chromatography tandem mass spectrometry. RESULTS: In RBC supernatants, 401 proteins were identified: 203 increased with storage, 114 decreased, and 84 were unchanged. In LR-RBC supernatant, 231 proteins were identified: 84 increased with storage, 30 decreased, and 117 were unchanged. Prestorage leucoreduction removed many platelet- and leucocyte-derived structural proteins; however, a number of intracellular proteins accumulated including peroxiredoxins (Prdx) 6 and latexin. The increases were confirmed by immunoblotting, including the T-phosphorylation of Prdx-6, indicating that it may be functioning as an active phospholipase. Active matrix metalloproteinase-9 also increased with a coinciding decrease in the metalloproteinase inhibitor 1 and cystatin C. CONCLUSION: We conclude that a number of proteins increase with RBC storage, which is partially ameliorated with leucoreduction, and transfusion of stored RBCs may introduce mediators that result in adverse events in the transfused host.

Rapid washing of filter paper discs in a solid-phase radioimmunoassay with a constant flow washing device.

A machine has been developed for the rapid washing of the cellulose filter paper discs that are used in a number of radioimmunoassays. The machine is simple in design, easy to use, and is capable of washing 96 filter paper discs simultaneously. The efficiency of the machine is demonstrated by a RAST assay for measuring IgE antibodies to the venom. Time taken to wash the discs was reduced 3-fold without loss of sensitivity or reproducibility.