Effects of binding of ligand (FVIIa) to induced tissue factor in human endothelial cells

The tissue factor protein is structurally related to the cytokine receptors and ligand binding (factor VIIa) has been reported to give an intracellular calcium signal, thus indicating that tissue factor is a true receptor. In view of the attempts to use recombinant factor VIIa as a therapeutic agent in hemophilia, its binding effects may be of clinical interest. We have studied the effect of ligand binding to human endothelial cells that were stimulated with interleukin-1 to express tissue factor. Human umbilical cord vein endothelial cells produce and release a wide variety of proteins that participate in coagulation and fibrinolysis, and we have investigated whether binding of recombinant factor VIIa to tissue factor altered the release of some of these compounds. Three main findings are reported. (1) After an initial increase, the measurable tissue factor activity in endothelial cells decreased more rapidly in the presence of factor VIIa (half-life 3.7+/-0.7 hours) than in its absence (half-life 7.4+/-1.5 hours). This difference was not seen when tissue factor antigen was measured, indicating that ligand binding did not increase the degradation of the protein. (2) Tissue factor pathway inhibitor was detected on the cell surface, in cell homogenates, and in cell medium. When recombinant factor VIIa was added to the cells there was a significant decrease in the release of tissue factor pathway inhibitor to the medium. Four hours after recombinant factor VIIa was added, the levels were 7.5-fold higher in the medium of untreated cells compared to the medium of cells treated with recombinant factor VIIa. (3) We observed increased release of von Willebrand factor (vWF). After 1 and 6 hours with recombinant FVIIa the release was significantly greater than in controls without FVIIa. We did not detect significant differences in the release of tissue plasminogen activator or tissue factor pathway inhibitor.

[alpha-thalassemia accompanied with Gilbert's syndrome]

A 15-year-old boy was admitted to our hospital because of microcytic hypochromic erythrocytosis and hyperbilirubinemia in October 1996. The laboratory findings were RBC: 597 x 10(4)/microliter, Hb: 13.1 g/dl, Ht: 40.8%, MCV: 70fl, MCH: 22pg, total bilirubin: 3.2 mg/dl (indirect: 2.2 mg/dl), s-Fe: 99 micrograms/dl, and ferritin: 25 ng/ml. Routine liver function tests were normal. There were no findings of hemolysis except for an increase in serum indirect bilirubin and reticulocytes. Decreased erythrocyte osmotic fragility was observed. The patient's mother and sister also showed microcytic hypochromic erythrocytosis. PCR analysis of genomic DNA from this patient, his mother, and his sister confirmed the diagnosis of the alpha-thalassemia trait. However, the bilirubin-UDP-glucuronosyltransferase 1 (B-UGT 1) gene mutation and the findings of the fasting test indicated the simultaneous presence of Gilbert's syndrome. The association of these two diseases in the same patient appears to be rare, especially in Japan because of the low incidence of thalassemia in this country. We concluded that the hyperbilirubinemia was caused by decreased bilirubin clearance, not by increased erythrocyte destruction.

Acute myeloid leukemia accompanied by multiple thrombophlebitis

A 66-year-old woman suffering from fever and thrombophlebitis was referred to our hospital. A peripheral blood examination revealed hyperleukocytosis with 96% blast cells and thrombocytopenia. The patient was diagnosed as having acute myeloid leukemia (AML) accompanied by disseminated intravascular coagulation (DIC). A marked decrease in protein C (PC) antigen and activity were observed. In this case, PC levels were lower than those observed in AML with DIC. Induction therapy for leukemia and treatment of DIC were started on the first day of hospitalization. The patient achieved complete remission, with PC antigen and activity levels normalized.

[Elderly non-hemophiliac patient with factor VIII inhibitor presenting various type hemorrhages]

A 81-year-old man who had been healthy without any history of abnormal bleeding, developed ecchymosis and hematuria in November, 1992 and was hospitalized in December, 1992. On admission, he developed widespread ecchymosis in his trunk and extremities, and subsequently ecchymosis of his cheek and neck, and also oral and pharyngeal hematoma. The laboratory data were as follows: whole blood clotting time, > 20 minutes; activated partial thromboplastin time (APTT), 108.6 seconds; Factor VIII activity, 4%. The level of Factor VIII inhibitor was high, 65.0 Bethesda Unit/ml. This inhibitor was a IgG type immunoglobulin, which had both kappa and lambda light chain. His serological and blood biochemical data of the blood were normal, and tests for autoantibodies were negative. The patient was treated with plasma exchange therapy, Prednisolone (PSL), Cyclophosphamide and Factor VIII concentrate. The hemorrhagic symptoms were improved, the inhibitor disappeared and the activity of Factor VIII returned to normal after one month. Follow-up was continued in the outpatient clinic for 5 months. After the dose of PSL was decreased, he developed bloody sputum and hematuria, and was readmitted in August, 1994. Factor VIII activity was 21% and the titer of Factor VIII inhibitor was 3.0 BU/ml. The hemorrhagic symptoms disappeared soon after increasing the dose of PSL, and the Factor VIII activity was normalized and the inhibitor could not be detected. These treatments appeared to offer effective control on severe hemorrhage in a patient with Factor VIII inhibitor.

Polar expression of tissue factor in human umbilical vein endothelial cells

Endothelial cells grown on filters developed junctional complexes that reduced diffusional transport and increased electrical resistance over the cell layer. Induction of tissue factor by recombinant interleukin-1 beta led to a highly polarized tissue factor expression on the apical cell surface only. After prolonged growth to allow deposition of matrix, removal of the endothelial cells by collagenase or by 0.1 mol/L NH4OH left behind some cellular material as well as tissue factor, which was only detectable in the upper compartment. A human bladder carcinoma cell line, which does not form tight junctions and expresses tissue factor constitutively, showed essentially no polarity. Endothelial cell secretory compounds like von Willebrand factor, tissue plasminogen activator, and plasminogen activator inhibitor-1 were constitutively released to both sides. The added secretion due to recombinant interleukin-1 beta stimulation of the endothelial cells observed for von Willebrand factor and tissue plasminogen activator was, however, localized to the apical surface. The availability of tissue factor on the luminal surface of endothelial cells, ie, allowing contact with factor VII in the flowing blood, has potentially very significant pathophysiological consequences.

Impairment of ristocetin-induced platelet aggregation in patients with infective endocarditis

An investigation was carried out on two patients with infective endocarditis associated with reduction of ristocetin-induced aggregation of platelets. The plasma of these patients reduced the aggregability with ristocetin of normal platelets. It is suggested that the patients had certain plasma factors which disturbed platelet aggregation with ristocetin.

[Combination therapy with granulocyte colony-stimulating factor (G-CSF) and erythropoietin (EPO) induced prominent granulocyte increase in an elderly case of myelodysplastic syndrome (MDS)]

A 70-year-old man was admitted to our hospital with pancytopenia. He was diagnosed as having MDS (RA), and therapy with subcutaneous S-CSF (100 micrograms/day) was started. His leukocyte count increased from 800/microliters to 1,400/microliters in two weeks. The dose of G-CSF was raised to 200 micrograms/day in the third week, and leukocytes increased to 2,00/microliters. At the fifth week, intravenous EPO (6,000 U x 3 times/week) was added. His leukocyte count increased to 4,000/microliters. EPO therapy was raised to 12,000 U x 3 times/week at the eighth week, his leukocyte count remained at the same level. G-CSF and EPO was stopped at the eleventh week, and leukocytes decreased to the same level as before administration. Throughout the course, his platelet count and reticulocyte count did not change. G-CSF and EPO are known as the stimulators of granuriod and erythroid progenitor, respectively. However, in this case, combination therapy with G-CSF and EPO induced marked increase of granulocytes only. This was an interesting case in relation to the roles of these cytokines in the hematopoietic system.

Induction of tissue factor synthesis in human umbilical vein endothelial cells involves protein kinase C

Incubation of human umbilical vein endothelial cells with one of the following compounds: endotoxin, recombinant interleukin-1 beta, recombinant tumor necrosis factor alpha, allogenic lymphocyte subpopulations or phorbol ester resulted in significant induction of tissue factor synthesis. Diacylglycerol had the same effect and also enhanced synergistically the induction caused by endotoxin and interleukin-1 beta. Two different inhibitors of protein kinase C, H7 and sphingosine, inhibited tissue factor synthesis at concentrations which did not depress protein synthesis in general, suggesting that protein kinase C is involved in the processes leading to tissue factor synthesis. Cells down-regulated for the tissue factor response to TPA responded essentially normally to endotoxin and interleukin-1 with regard to tissue factor synthesis.

One-stage method for assay of tissue factor activity of leukemic cell with special reference to disseminated intravascular coagulation

Tissue factor activity (TFA) of leukemic cells (1 x 10(8) cells/mL) was measured in 44 patients with acute nonlymphoid leukemia (ANLL) by the one-stage assay using factor-IX deficient plasma (OSA-dIX) and two-stage assay (TSA). According to the preventative heparin dose schedule based on the TFA measured by the TSA, all disseminated intravascular coagulation (DIC) was controlled successfully. The procedure of the TSA was too complicated for clinical use, and its minimal measurable value was 125 units (U)/L of TFA. The OSA-dIX was simpler in its procedure and sensitive enough to measure accurately a TFA quantity as small as 30 U/L with high reproducibility. In 20 ANLL patients with 125 U/L or more of TFA measured by both assays, there was a significant relationship between their logarithms of TFA (r = 0.93, P less than 0.01). These results suggested that DIC complication in ANLL patients would be controlled successfully by the administration of heparin dosage based on the TFA measured by the OSA-dIX.

Interaction of plasma clotting factors with vascular endothelial cells in hemostasis and thrombosis with special reference to endothelial cell tissue factor

The interaction of plasma clotting factors with vascular endothelial cells was investigated. Human umbilical cord vein endothelial cells generated tissue factor activity after treatment with various stimulators including IL-1. Cycloheximide inhibited production of the tissue factor in the cells, but did not affect the expression of the tissue factor activity on the surface of endothelial cells. Endotoxin-treated vascular endothelial cells activated Factor X in the presence of Factor VII and calcium ion. Activation of Factor X by endothelial cells with Factor VII was enhanced by the presence of both Factors VIII and IX. Binding study revealed that endotoxin-treated endothelial cells bound Factor IX. These data suggest that perturbed vascular endothelium expresses tissue factor activity on the cell surface, binds factor IX and in the presence of Factor VII, activates not only factor X but also Factor IX.

Studies on leukemic cell tissue factor

Apoprotein part of tissue factor of human placenta was purified 871 fold from the starting material with 4.2% yield by concanavalin A-Sepharose affinity chromatography and SDS-PAGE. The molecular weight of purified apoprotein was 45,000 in non-reduced condition and 49,000 in reduced condition. Tissue factor of human leukemia cells (FAB classification:M2 and M3) and cultured leukemia cell lines (HL-60 and Molt-4) was analyzed using specific rabbit anti-tissue factor IgG raised against purified material. Endotoxin stimulated HL-60 and Molt-4 also expressed procoagulant activity which was inhibited by tissue factor immune IgG. By immunostaining of the purified material, the lysate of leukemia cells (M2 and M3) and cultured leukemia cells (HL-60 and MOLT-4) revealed a major band of the same apparent molecular weight. Immuno-electron microscopic study on tissue factor of HL-60 cells produced the following findings: stimulation by endotoxin resulted in the formation of pseudopods of the cell membrane, and immunogold particles accumulated mainly on these pseudopods and cisternal spaces of rough endoplasmic reticulum, indicating exposure of the tissue factor to the surface of perturbed cell membrane with concurrent increase in tissue factor synthesis.