Intracellular and Surface Distribution of Monocyte Tissue Factor

Abstract

Objective-The high and low responder phenomenon describes individual differences in lipopolysaccharide (LPS)-induced monocyte tissue factor (TF) activity. We characterized patterns of intracellular accumulation, externalization, and shedding of TF in response to LPS in mononuclear cells (MNCs) from high responders (HRs) and low responders (LRs). T ightly controlled exposure of tissue factor (TF) to components of the plasma coagulation cascade is important for maintenance of normal rheological properties of blood. Failure to manipulate TF levels available for the initiation of blood clotting leads to thrombotic or bleeding disorders in humans. Circulating monocytes are presumably the major cell type that respond to variable stimuli by developing coagulant activity 1 through the expression of TF. 2 Originally, intersubject variability in developing of monocyte TF activity was described by Østerud et al. 3 By comparing lipopolysaccharide (LPS)-induced monocyte TF activity and tumor necrosis factor-␣ (TNF-␣) production in a whole blood system, an up to a 50-fold difference between individuals was observed. 4 This finding was defined as the "highlow responder phenomenon." 4 Also noteworthy, the individual usually remains a high responder (HR) or low responder (LR) for several years. 5,6 Later, high intersubject variability in cytokine production by LPS-stimulated monocytes was demonstrated. 7 It was also shown that patients with high levels of TNF-␣ production were more susceptible to heart transplant rejection. 8 Monocytes isolated from septic shock patient survivors revealed higher TNF-␣ production than monocytes from nonsurvivors. 9 Many studies have been undertaken to describe the significance of this phenomenon, but so far, no general explanation has been found. Diverse plasma factors and direct cell interactions play an important role in the development of monocyte TF activity. 10 -15 High expression of monocyte TF activity is associated with higher risk of acute coronary syndrome. 16 Platelets have been suggested to be responsible for inducing monocyte TF activity. 17 Platelet-rich plasma induced significantly higher TF activity in LPS-stimulated monocytes than platelet-poor plasma. 18 Moreover, when blood cells without platelets from HRs were mixed with platelet-rich plasma of an LR, LPS-induced TF activity was reduced up to 76% compared with an autologous system. 18 It was shown that granulocytes enhance LPSinduced monocyte TF activity in a platelet-dependent reaction involving P-selectin, platelet factor 4, plateletactivating factor, hydroxyl-eicosatetraenoic acid, and platelet-derived growth factor. 18 -21 Here we report several observations concerning the relationships between intracellular-and membrane-located TF antigen in resting and LPS-stimulated monocytes in groups of HRs and LRs, using fluorescence-activated cell sorter (FACS) analysis, fluorescence confocal microscopy, in-cell Methods and Results-After Materials and Methods Blood Sampling and Experimental DesignBlood samples from 16 healthy ...

Extracellular, cell-permeable survivin inhibits apoptosis while promoting proliferative and metastatic potential

“…It is uncertain whether bacterial-derived survivin proteins are folded or modified properly for recognition by cellular mechanisms of uptake. To test this hypothesis further, we evaluated recombinant survivin (BIRC5), transferrin, and CTB proteins for cellular uptake using in-cell western assay methods (Egorina et al, 2005). HeLa cells were incubated with increasing concentrations of labelled recombinant protein, and the amount of protein endocytosed after a 12 h incubation was measured as shown in Figure 6.…”

Comparison of natural and recombinant tissue factor proteins: new insights

“…However, our data using quantitated concentrations of TF on LPS-stimulated monocytes and in their lysates (Parhami -Seren et al, 2004 ) indicate that TF activity in both cases is similar, with the latter being only 1.3-fold more efficient than the former (Table 3, Figure 2). The difference in TF activity on monocyte surface and their lysates is, most likely, related to the release of TF from the intracellular stores upon the treatment of stimulated cells (Egorina et al , 2005(Egorina et al , , 2006. Monocyte-expressed TF binds factor VIIa and initiates proteolytic activation of factor X (Edwards and Rickles , 1984 ) and factor IX (Worfolk and Tracy , 1995 ).…”

Candida albicans effects the tissue factor activity of blood cells in Type II Diabetes Mellitus

“…In general, circulating blood cells do not express TF in healthy individuals (22,23), although very low levels of TF antigen have been detected in a small subset of CD14-positive monocytes (24,25). Patients with type II DM have higher levels of circulating TF, as well as increased monocyte TF mRNA, which are directly modulated by both glucose and insulin, with an additive effect (9,26,27).…”