Expression of tissue factor and factor VIIa/tissue factor inhibitor
activity in endotoxin or phorbol ester stimulated U937 monocyte-like cells
SV Rana, HJ Reimers, MS Pathikonda and SP Bajaj
Section of Medicine, St Louis University School of Medicine, MO.
Previously, unstimulated cells of the human monocytic tumor cell line U937
have been shown to possess a negligible cell-surface tissue factor (TF)
activity, and to secrete a small amount of factor VIIa/tissue factor
(VIIa/TF) inhibitor activity. On stimulation with endotoxin or with phorbol
myristate acetate (PMA), TF of these cells is known to be increased
approximately fourfold. In this report, we demonstrate that VIIa/TF
inhibitor is also increased on stimulation of U937 cells with endotoxin
(approximately equal to threefold) or with PMA (approximately equal to
20-fold). Notably, the secretion of the inhibitor persisted after the cell
surface TF had started to decline. Further, when serum- free media from PMA
stimulated cells was electrophoresed on a sodium dodecyl sulfate (SDS) gel,
we eluted two inhibitor activity peaks corresponding to Mr approximately
equal to 47,000 and Mr approximately equal to 36,000. The molecular weights
of these peaks are similar to those obtained earlier from human plasma for
this inhibitor(s).
Volume 71,
Issue 1,
pp. 259-262,
01/01/1988
Copyright © 1988 by The American Society of Hematology
