The pro-inflammatory potential of microparticles in red blood cell units.
BACKGROUND
Microparticles (MPs) are submicron size cell fragments that are released from cells.


OBJECTIVE
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
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.


CONCLUSIONS
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.
Research Laboratory, Bonfils Blood Center, Denver, Colorado, USA; Department of Pediatrics, University of Colorado, Denver, Colorado, USA.
M W
MW
Kent
M R
MR
Kelher
F B
FB
West
C C
CC
Silliman
D001793:Blood Preservation; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D004912:Erythrocytes; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D008297:Male; D018375:Neutrophil Activation; D009504:Neutrophils / Q000378:metabolism* / Q000473:pathology
TRALI; leucoreduction; neutrophils; priming; supernatants