Phosphatidylserine index as a marker of the procoagulant phenotype of acute myelogenous leukemia cells

Abstract

Summary Background Patients with Acute Myelogenous Leukemia (AML) are at risk for thrombotic complications. Risk to develop thrombosis is closely tied to leukemia subtype, and studies have shown an association between leukocytosis and thrombosis in AML M3. Objective To investigate the relative roles of cell count and the surface expression of tissue factor (TF) and phosphatidylserine (PS) in the procoagulant phenotype of AML cell lines. Methods and Results We evaluated the relative roles of cell count and the surface expression of TF and PS in the procoagulant phenotype of AML cell lines. The TF-positive AML M3 cell lines, NB4 and HL60, and AML M2 cell line, AML14, exhibited both extrinsic tenase and prothrombinase activity in a purified system and promoted experimental thrombus formation. In contrast, the TF-negative AML cell line, HEL, exhibited only prothrombinase activity and did not affect the rate of occlusive thrombus formation. In plasma, NB4, HL60 and AML14 shortened clotting times in a cell-count, PS- and TF-dependent manner. Exposure of cultured NB4, HL60, and AML14 cells to the chemotherapeutic agent daunorubicin increased their extrinsic tenase activity and PS expression. Clot initiation time inversely correlated with logarithm of PS index, defined as the product of multiplying leukocyte count with cell surface phosphatidylserine exposure. Conclusion Cultured AML cell lines promote coagulation in a cell count-, TF- and PS-dependent manner. We propose that leukemia cell PS index may serve as a biomarker for procoagulant activity and help identify patients with AML that may benefit from thromboprophylaxis.

Effect of ATRA and ATO on the expression of tissue factor in NB4 acute promyelocytic leukemia cells and regulatory function of the inflammatory cytokines TNF and IL-1β

“…The effect of ATRA on TF protein and activity is delayed with respect to its rapid effect on TF mRNA and is only evident at 24 h. Even then, significant procoagulant activity is still detected and this information is quite relevant in the context of reducing hemorrhagic complication in the early treatment phase [ 57 ]. In agreement with previous reports [ 58 , 59 ], we found with the CAT assay that cells and microparticles bring both TF and an appropriate surface, since a substantial inhibition was obtained in presence of anti-TF antibody and since we did not add extra phospholipids. Of note, inhibition of thrombin generation as assessed with the CAT assay appeared to be less than that measured with the artificial Xa generation assay.…”

The prothrombotic activity of cancer cells in the circulation

“…In support of this, in vitro studies have shown heterogeneity in cancer cell surface expression of TF and PS, both of which are critical to determining the procoagulant phenotype of cancer cells. As such, the utility of implementing CTC analysis as a means to rationally base thrombosis prophylaxis may hinge upon determining critical features of CTCs in addition to CTC counts as a marker for risk to develop thrombosis (114). …”

Prognostic implications and procoagulant activity of phosphatidylserine exposure of blood cells and microparticles in patients with atrial fibrillation treated with pulmonary vein isolation

“…Exposure of PS on the outer leaflet and microparticles (MPs) are found in the process of apoptosis ( 12 , 13 ). In addition, PS exposure on the outer membrane surface can function as a docking site for various coagulation proteins, including factor (F)VII, FIX, FV, FVIII, FX and prothrombin, and promote the formation of thrombin ( 14 , 15 ). As a primary cellular initiator of blood coagulation via interaction with coagulation FVII, tissue factor (TF) is generally quiescent unless it resides on a cell membrane containing PS ( 16 ).…”