Although about 80% of tissue factor (TF) extracellular domain antigen present in
lipopolysaccharide (LPS)-stimulated monocytes is available at the cell surface, only 10% to
20% of the total extractable TF activity is expressed on the surface of intact monocytes. Thus,
most of the TF activity is latent or encrypted in the cell membrane. When coincubated,
leukocytes and platelets generate more TF activity than either cell type alone. We have
shown that such platelet-promoted enhancement of LPS-induced TF activity in monocytes in …