Generation of phenotypically aged phosphatidylserine-expressing
erythrocytes by dilauroylphosphatidylcholine-induced vesiculation
C Diaz, J Morkowski and AJ Schroit
Department of Cell Biology, The University of Texas M.D. Anderson Cancer
Center, Houston, USA.
In vitro stored red blood cells (RBC) and RBC artificially induced to
vesiculate by incubation with dilauroylphosphatidyl-choline were monitored
for age- and vesiculation-dependent changes in cell density, membrane lipid
asymmetry, and their ability to be recognized and cleared by
reticuloendothelial cells. RBC demonstrated a progressive increase in
density on self-forming Percoll gradients upon vesiculation and in vitro
"aging." Uptake of vesiculated RBC by in vitro cultivated macrophages was
increased threefold over non-vesiculated control RBC. The clearance rate of
dense vesiculated RBC was biphasic and contained a rapid component and a
slower second component consistent with the clearance rates of normal
control populations. Determination of phosphatidylserine (PS) in the outer
leaflet of RBC by the PS-dependent prothrombinase assay revealed that PS
redistributed to the cell's outer leaflet upon in vitro storage and
vesiculation. Inhibition of PS movement by oxidation of membrane
sulfhydryls with pyridyldithioethylamine resulted in higher prothrombinase
levels and enhanced clearance of vesiculated RBC. These experiments suggest
that vesiculation contributes to alterations in membrane lipid asymmetry
and cell density characteristic of the aged RBC phenotype.
Volume 87,
Issue 7,
pp. 2956-2961,
04/01/1996
Copyright © 1996 by The American Society of Hematology
