Association of tissue factor with a gamma chain homodimer of the IgE receptor type I in cultured human monocytes

Eur J Immunol. 1996 Oct;26(10):2529-32. doi: 10.1002/eji.1830261037.


Tissue factor (TF) is a high-affinity receptor for coagulation factors VII (F VII) and VIIa. The F VII/VIIa/TF complex is the major cellular initiator of the extrinsic coagulation cascade. We found that the occupancy of TF by its ligand, F VIIa, is involved with signal transduction and that TF is associated with the gamma chain homodimer identified as a component of IgE receptor type I (Fc epsilon RI). When 4-day cultured human monocytes were incubated with F VIIa, several polypeptides, especially a 70-kDa polypeptide, were transiently phosphorylated on tyrosine, residues. These phosphorylation events were inhibited by prior binding of anti-TF monoclonal antibody (mAb) HTF-K14, but not anti-TF mAb HTF-K180 to intact cultured monocytes. HTF-K14 blocked the binding of F VII/ VIIa to cell surface TF, whereas HTF-K180 did not. Anti-TF immunoprecipitates prepared from 1% digitonin lysates of cultured human monocytes incorporated phosphate in a gamma chain homodimer when incubated with [gamma-32P] ATP. The identity of the T-associated structures as gamma chains was established by immunoblot analysis of anti-TF mAb immunoprecipitates with anti-gamma chain mAb. In addition, anti-TF immunoblot analysis showed that TF co-precipitated with anti-gamma chain mAb. Our data suggest that gamma chains may play an important role in signaling via TF in human monocytes/macrophages.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cells, Cultured
  • Factor VIIa / metabolism
  • Humans
  • Macrophages / immunology
  • Macrophages / metabolism
  • Monocytes / immunology*
  • Monocytes / metabolism
  • Phosphorylation
  • Phosphotyrosine / metabolism
  • Protein Binding
  • Receptors, IgE / metabolism*
  • Signal Transduction
  • Thromboplastin / metabolism*


  • Receptors, IgE
  • Phosphotyrosine
  • Thromboplastin
  • Factor VIIa