Influence of blood storage age on immune and coagulation parameters in critically ill transfused patients

BACKGROUND

Several retrospective studies have suggested that transfusion with red blood cells (RBCs) stored for longer periods is associated with increased mortality. The Age of Blood Evaluation (ABLE) study randomized subjects to receive fresh vs. standard issue RBC units and showed no difference in the primary or secondary endpoints of mortality or change in multi-organ dysfunction syndrome (MODS) score.

METHODS

In this study a subset of 100 ABLE subjects were enrolled to measure coagulation and immune parameters. Samples were collected pre-transfusion and on days 2, 6, 28, and 180 post-transfusion. Levels of 16 coagulation parameters, regulatory and functional T cells, 25 cytokines, and 16 markers of extracellular vesicles (EVs) were determined.

RESULTS

Changes from baseline in levels of protein C, factor V, and EVs expressing phosphatidyl serine and CTLA-4 (CD152) differed between recipients of fresh and standard storage age RBC units, with the vast majority of coagulation and EV markers and all cytokines tested showing no difference between study arms. Although most analytes showed no difference between subjects in the fresh and standard arms of the study, 6 coagulation parameters, 15 cytokines, and 7 EV parameters changed significantly in the period post-transfusion.

DISCUSSION

Transfusion of fresh vs. standard issue RBC units does not result in substantial changes in coagulation or immune parameters, up to day 35 of RBC storage. Furthermore, significant changes in multiple coagulation and immune parameters are detectable post-transfusion, though causality cannot be determined based on the current study.

Granulocyte-Derived Extracellular Vesicles Activate Monocytes and Are Associated With Mortality in Intensive Care Unit Patients

To understand how extracellular vesicle (EV) subtypes differentially activate monocytes, a series of in vitro studies were performed. We found that plasma-EVs biased monocytes toward an M1 profile. Culturing monocytes with granulocyte-, monocyte-, and endothelial-EVs induced several pro-inflammatory cytokines. By contrast, platelet-EVs induced TGF-β and GM-CSF, and red blood cell (RBC)-EVs did not activate monocytes in vitro. The scavenger receptor CD36 was important for binding of RBC-EVs to monocytes, while blockade of CD36, CD163, CD206, TLR1, TLR2, and TLR4 did not affect binding of plasma-EVs to monocytes in vitro. To identify mortality risk factors, multiple soluble factors and EV subtypes were measured in patients' plasma at intensive care unit admission. Of 43 coagulation factors and cytokines measured, two were significantly associated with mortality, tissue plasminogen activator and cystatin C. Of 14 cellular markers quantified on EVs, 4 were early predictors of mortality, including the granulocyte marker CD66b. In conclusion, granulocyte-EVs have potent pro-inflammatory effects on monocytes in vitro. Furthermore, correlation of early granulocyte-EV levels with mortality in critically ill patients provides a potential target for intervention in management of the pro-inflammatory cascade associated with critical illness.

All optical switch of vacuum Rabi oscillations: the ultrafast quantum eraser

We study the all-optical time control of the strong coupling between a single cascade three-level quantum emitter and a microcavity. We find that only specific arrival times of the control pulses succeed in switching off the Rabi oscillations. Depending on the arrival times of control pulses, a variety of exotic nonadiabatic cavity quantum electrodynamics effects can be observed. We show that control pulses with specific arrival times, performing which-path and quantum-eraser operations, are able to suddenly switch-off and on first-order coherence of cavity photons, without affecting their strong coupling population dynamics.