Procoagulant activity of T lymphoblastoid cells due to exposure of negatively charged phospholipid.
We have characterised the Procoagulant activity (PCA) of six well-established cell lines by assays of tissue factor (TF), thrombin and FXa generation, flow cytometry using Annexin V, and by binding studies with Factors VIII and IXa. The monocytic (THP-1 & U937) and promyelocytic (NB4) cells expressed high concentrations of TF antigen and activity, whereas TF in the lymphocytic cells (Molt 4, Jurkat & Nalm 6) was very low or absent. However the T-lymphoblastoid cells (Molt 4 & Jurkat) promoted the generation of large amounts of thrombin despite their low TF content, and these cells were also the most active in supporting Factor Xa generation. Molt 4 cells bound Factors VIII and IXa with high capacity and their activity was inhibited by Annexin V. These results indicate that the PCA of T-lymphoblastoid lines is due to expression of negatively charged phospholipids. Flow cytometry studies showed Annexin V binding to the major population of nonapoptotic Molt 4 cells and the PCA of Molt 4 was not increased when apoptosis was induced by staurosporine, indicating that PCA is independent of apoptotic status.
Barrowcliffe
T W
TW
Division of Haematology, NIBSC, Herts, UK. tbarrowcliffe@nibsc.ac.uk
Fábregas
P
P
Jardi
M
M
Cancelas
J
J
Rabaneda
M
M
Felez
J
J
D000838:Anions / Q000378:metabolism; D017209:Apoptosis; D002462:Cell Membrane / Q000378:metabolism; D015949:Factor IXa / Q000378:metabolism; D005169:Factor VIII / Q000378:metabolism; D006801:Humans; D010718:Phosphatidylserines / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D011485:Protein Binding; D013601:T-Lymphocytes / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure*; D019851:Thrombophilia / Q000209:etiology* / Q000473:pathology; D013925:Thromboplastin / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000838:Anions; D010718:Phosphatidylserines; D010743:Phospholipids; D005169:Factor VIII; D013925:Thromboplastin; D015949:Factor IXa