EXPRESSION OF TISSUE FACTOR AND FACTOR-VIIA/TISSUE FACTOR INHIBITOR ACTIVITY IN ENDOTOXIN OR PHORBOL ESTER STIMULATED U937 MONOCYTE-LIKE CELLS

  • 1 January 1988
    • journal article
    • research article
    • Vol. 71  (1) , 259-262
Abstract
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 Vlla/tissue factor (Vlla/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 Vlla/TF inhibitor is also increased on stimulation of U937 cells with endotoxin (.simeq.3-fold) or with PMA(.simeq.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 .simeq.47,000 and Mr .simeq.36,000. The molecular weights of these peaks are similar to those obtained earlier from human plasma for this inhibitors(s).