Compromised activity of natural killer cells in diffuse large b-cell lymphoma is related to lymphoma-induced modification of their surface receptor expression.

While natural killer (NK) cells are essential players in detection and elimination of malignant cells, these surveillance properties can be compromised by cancer cells. Since NK cell education primarily occurs in the bone marrow and lymphoid tissue, this process might be particularly affected by their infiltration with lymphoma cells. This study aimed to explore functional properties of diffuse large B-cell lymphoma (DLBCL) patient NK cells, which could potentially promote tumour immune evasion and disease propagation.NK cells isolated from the peripheral blood (PB) of 26 DLBCL patients and 13 age-matched healthy controls (HC) were analysed. The cytotoxic CD56dim subtype was the only one identified in patients. Compared to HC, patient cells demonstrated low levels of inhibitory CD158a/b along with decreased expression of activating NKG2D and CD161 and increased inhibitory NKG2A levels. Patient NK cell cytotoxic activity was impaired, as were their degranulation and inflammatory cytokine production, which partially recovered following non-receptor-dependant stimulation.The phenotypically skewed and restricted population of patient NK cells, along with their blunted cytotoxic and immune-regulatory activity, appear to be driven by exposure to lymphoma environment. These NK cell functional aberrations could support lymphoma immune evasion and should be considered in the era of cellular therapy.

Pregnancy and non-pregnancy related immune thrombotic thrombocytopenic purpura in women of reproductive age.

Pregnancy is a precipitating factor for immune thrombotic thrombocytopenic purpura (iTTP). We compared the clinical course and outcomes of iTTP in women of reproductive age, between those with pregnancy- and non-pregnancy-related iTTP. A review of all reproductive-aged women diagnosed with iTTP during 2010-2019 in seven university hospitals in Israel. Of 42 cases of iTTP, 12 (28.6%) were pregnancy-related. At presentation, the laboratory profiles did not differ significantly between those with pregnancy- and non-pregnancy-related iTTP, including hemoglobin (median 8.4 vs 8.0 g/dL), platelet count (12.5 vs. 11.5 X 109/L); and levels of bilirubin (1.23 vs. 1.82 mg/dL), lactate dehydrogenase (1615 vs. 1701 U/L), creatinine (0.61 vs. 0.79 mg/dL) and anti-ADAMTS13 antibodies titer (75 vs. 82 U/mL). The proportions of women with renal, neurologic, or hepatic involvement were similar between the groups. Cardiac involvement was more common among those with pregnancy-related disease (25.0% vs. 3.3%, P = 0.06). The median number of courses of plasma-exchange therapy was 11 for both groups. All the women were treated with parenteral corticosteroids and the rate of adjunctive treatments did not differ between the groups (P = 0.30). Four women (one-third) with pregnancy-related disease had preeclampsia. Two women (16.7%) with pregnancy-related iTTP died during the acute episode (P = 0.07); no deaths were observed in the non-pregnancy-related group. Among reproductive-aged women with iTTP, most clinical and laboratory profiles were similar between those with pregnancy- and non-pregnancy-related disease. However, the higher rates of cardiac involvement and mortality among women with pregnancy-related iTTP highlight its challenging management.

Protein C global assay evaluation in naturally conceived vs. assisted reproduction-achieved twin pregnancies: a prospective longitudinal study.

PURPOSE: Protein C global assay tests the global function of the protein C pathway, the most clinically significant anticoagulant pathway in humans. The objective of this study is to assess the difference in protein C global assay levels, throughout twin gestation, in naturally conceiving and ART-treated women. METHODS: This is a prospective cohort longitudinal study of pregnant women with twin gestation. Protein C Global evaluation was performed on frozen blood samples. Ninety-eight women with twin pregnancy, thirty-eight naturally conceived and sixty following ART, were evaluated on four occasions: during the first, second, and third trimesters, and 6 weeks or later after delivery (baseline). RESULTS: Protein C global assay levels were lower throughout pregnancy as compared to basal levels in both the naturally conceived and ART-conceived groups. However, protein C global assay levels were similar between the ART-conceived and naturally conceived twin pregnancies in all three trimesters. Perinatal complications were associated with decreased protein C global assay levels during the third trimester, although no difference was encountered between naturally conceived and ART-complicated twin pregnancies. CONCLUSION: While protein C global assay levels drop during twin pregnancy, there is no difference between ART-conceived and naturally conceived gestations. Decreased levels of protein C global assay during the third trimester were similarly associated with perinatal complications in both groups. Our results imply that twin pregnancy of itself is a more dominant factor for perinatal complications as compared to other factors, such as subfertility or the exposure to ART per se.

[EXPERIENCE IN DIAGNOSTIC ASSAYS FOR HEPARIN-INDUCED THROMBOCYTOPENIA - EXPERIENCE OF A TERTIARY HOSPITAL IN ISRAEL].

AIMS: To analyze the experience of a tertiary medical center in clinical and laboratory diagnosis of suspected HIT. BACKGROUND: The diagnosis of heparin-induced thrombocytopenia (HIT) requires clinical data and laboratory detection of platelet activating factor 4/heparin (PF4/H) antibodies by immunological or functional assays. Although antigen screening assays are widely used, the functional assays are performed only by several expert labs. METHODS: A retrospective review of the Hematology Laboratory database on patients evaluated between the years 2008-2016 at Rambam, identified 412 individuals with clinical suspicion of HIT. Till 2011, 135 cases were screened using particle gel PaGIA (Biorad) and between the years 2012-2016, a total of 277 cases were screened by lateral flow Milenia (Biotec GmbH). All patients diagnosed with HIT were treated with Fondaparinux (Arixtra). Functional assay with heparin/LMWH induced platelet aggregation was performed using light transmission aggregometry (Helena AggRAM) to validate borderline or positive results in indistinct cases. RESULTS: From the tested samples, 63% vs. 75% were negative in PaGIA and Milenia, respectively (P=0.03), and were considered negative for HIT. During 2008-2011, only 38% of cases with non-negative immunoassay results underwent functional aggregation, whereas, in 2012-2016, 83% of such cases were further evaluated. None of the borderline PaGIA samples was positive in the functional assay compared to 13.3% borderline Milenia results; 25% of positive PaGIA and 51.7% of positive Milenia were confirmed by a positive functional HIT assay (P=N.S.). The survival rate among 14 patients with a positive functional assay was 42.7 % (6 patients). CONCLUSIONS: The Milenia assay introduced at our lab in 2012, has improved the screening process. The functional assay provides a more accurate HIT diagnosis. The combined approach of an optimal laboratory and clinical investigation is crucial to obtain a precise HIT diagnosis.

Effects of Acute Stress on Thrombosis.

Stress, the nonspecific response to any demand for change, is an adaptive response of the human body to various stimulants. As such, stress-induced hypercoagulation may represent an adaptive response to bleeding. Numerous epidemiological studies have revealed that a correlation exists between stress and thrombotic risk and biochemically, links of the relationship between psychological stress and coagulation pathways have been made. The stress reaction is coupled with neurohormonal changes mediated mainly by the sympathetic neural system and the hypothalamic-pituitary-adrenal axis. Singling out the specific pathways affecting coagulation in this complex response is hampered by many confounders. The mediators of the stress reaction (neurotransmitters and hormones) can directly affect platelets and the coagulation cascade and indirectly affect hemostasis via changes in hemodynamics. In this review, the authors will delineate the distinct neurobiological mechanisms that govern the effects of stress on coagulation, and report their recent findings.

A 14-Year Experience in the Management of Patients with Acquired Immune Thrombotic Thrombocytopenic Purpura in Northern Israel.

Acquired idiopathic thrombotic thrombocytopenic purpura (I-TTP) is a life-threatening microangiopathic disorder usually treated with therapeutic plasma exchange (TPE). The current study assessed the role of rituximab in the treatment of complicated I-TTP. The sequence of TTP events was compared in a group of I-TTP patients treated with TPE and a cohort of refractory or relapsed patients who also received rituximab. This retrospective evaluation included 45 I-TTP patients, treated between January 2000 and October 2013, who underwent at least 3 TPE procedures and were followed up until December 2013 or death. Thirty-one patients with an uncomplicated course received TPE only. Fourteen patients had a complicated course due to either a primary refractory/exacerbated disease (n = 5) or relapse (n = 9) and received rituximab together with TPE. The median number of TPE procedures performed in the first TTP episode in the uncomplicated cohort and groups with primary refractory or relapsed TTP was 11, 27 and 45, respectively. The relapse rates per follow-up year in the uncomplicated I-TTP, primary refractory and relapsed I-TTP groups were 0.18, 0.2 and 0.6 episodes, respectively. After rituximab therapy this rate dropped to 0.2 per year in the relapsed subgroup. In conclusion, about a quarter of patients with I-TTP had a complicated course and experienced a major benefit from rituximab in terms of effectiveness and safety.

Identification of a novel mutation in the PNLIP gene in two brothers with congenital pancreatic lipase deficiency.

Congenital pancreatic lipase (PNLIP) deficiency is a rare monoenzymatic form of exocrine pancreatic failure characterized by decreased absorption of dietary fat and greasy voluminous stools, but apparent normal development and an overall good state of health. While considered to be an autosomal recessive state affecting a few dozens of individuals world-wide and involving the PNLIP gene, no causative mutations for this phenotype were so far reported. Here, we report the identification of the homozygote missense mutation, Thr221Met [c.662C>T], in two brothers from a consanguineous family of Arab ancestry. The observed genotypes among the family members were concordant with an autosomal recessive mode of inheritance but moreover a clear segregation between the genotype state and the serum PNLIP activity was evident. Based on biophysical computational tools, we suggest the mutation disrupts the protein's stability and impairs its normal function. Although the role of PNLIP is well established, our observations provide genetic evidence that PNLIP mutations are causative for this phenotype.

Reduced protein C Global assay level in infertile women prior to IVF-ET treatment.

PURPOSE: In the last few years more robust evidence is emerging to point out at an increased rate of prematurity and low birth weight in singleton pregnancies following ART. Whether this increased rate is related to ART practice or to infertility per se, is still an open question. Our aim in this study was to explore this question by evaluating Protein C (ProC) Global assay in infertile women before ART treatment. METHODS: A cohort of 95 unselected and consecutive infertile women, eligible for ART, was prospectively recruited for the study. The control group included 77 matched healthy fertile women with a history of spontaneous conceptions. Pro C Global assay was evaluated in both groups. A full thrombophilic work-up was performed in the study group. RESULTS: ProC Global assay level was found to be significantly lower in the study as compared to the control group, corresponding to 0.78 ± 0.16 and 0.88 ± 0.16, respectively (P < 0.01). As well, abnormal ProC Global assay level of ≤ 0.8 was significantly higher in the study as compared to control group corresponding to 53 % and 29 %, respectively. ProC Global assay level was significantly lower in women within the study group found to have APCR, factor V Leiden and high factor VIII level, any thrombophilia or combined thrombophilia when compared to women without these thrombophilic risk factors. CONCLUSIONS: Reduced ProC Global assay level is encountered in infertile women prior to ART treatment. This finding may suggest a unique anticoagulation Protein C pathway in infertile as compared to fertile women. Further studies are encouraged to explore this finding.

Long-term response to rituximab in patients with relapsing thrombotic thrombocytopenic purpura.

Acquired thrombotic thrombocytopenic purpura (TTP) is an uncommon disease in adults, characterized by fever, neurological manifestations, microangiopathic hemolytic anemia, thrombocytopenia, renal dysfunction, and the presence of antibodies against the enzyme ADAMTS13. Treatment with plasmapheresis has increased the survival from 10% to more than 90%. Still, there is a subset of patients with resistant TTP who fail to respond to plasmapheresis or remain dependent on this procedure. There is mounting evidence that rituximab may play an important role in remission induction of resistant/relapsing TTP, but the extent of the remission is unknown. We present here four patients with chronic-relapsing TTP who responded favorably to rituximab. All four patients achieved prolonged remission of 23 to 82 months after the treatment. One patient relapsed 6 years afterthe initial treatment with rituximab and re-entered remission following retreatment.

Hypercoagulation in chronic post-traumatic stress disorder.

BACKGROUND: Whereas procoagulation abnormalities in acute stress are well established, little is known about the mechanism of hypercoagulation in chronic stress, such as post-traumatic stress disorder (PTSD). This is crucial, given the fact that chronic coagulation disturbances have been associated with increased morbidity and premature mortality due to thromboembolism and cardiovascular disorders, complications recently described in PTSD patients. OBJECTIVES: To explore the mechanisms of hypercoagulation in chronic PTSD. METHODS: Thirty patients diagnosed with chronic PTSD were enrolled and compared with a control group matched for age, gender and ethnicity. Hypercoagulation state was evaluated by levels of fibrinogen, D-dimer, prothrombin fragment F 1+2, von Willebrand factor (vWF) antigen, factor VIII activity, activated protein C resistance, ProC Global assay, and tissue factor antigen. Psychiatric evaluation was performed using the Mini-International Neuropsychiatric Interview and Clinician Administered PTSD Scale (CAPS). RESULTS: vWF antigen levels were significantly higher in patients with chronic PTSD compared with the controls (121.3 +/- 42 vs. 99.7 +/- 23, respectively, P = 0.034). Higher levels of vWF antigen and factor VIII activity were found in patients with severe chronic PTSD (CAPS > 80), compared to controls and patients with chronic PTSD and less severe symptoms (CAPS < or = 80). However, no differences were observed in any other studied coagulation parameters between patients and controls. CONCLUSIONS: Increased levels of vWF antigen and factor VIII activity were documented in severe chronic PTSD. These findings suggest that the higher risk of arterial and venous thromboembolic events in PTSD patients could be related to endothelial damage or endothelial activation.

[New scoring system for estimating the risk for pregnancy complications and venous thromboembolism in women with thrombophilia].

Pregnancy is an acquired state of hypercoagulation. An association has been found between various pregnancy complications and thrombophilia. Among those complications are: preeclampsia, intrauterine fetal death, intrauterine growth retardation and placentaL abruption. This article will present a novel scoring system estimating pregnancy complications in women with thrombophilia. The biological and epidemiological background of the association between pregnancy complications and thrombophilia will be discussed and the therapeutic options will be evaluated. Finally, for illustrative purposes, a patient presenting with combined thrombophilia--both genetic and acquired--will be discussed. This patient had suffered severe gestational complications that led to devastating obstetrical outcome.

Asymptomatic deep vein thrombosis in advanced cancer patients: the value of venous sonography.

PURPOSE: Although guidelines for venous thromboembolism prevention are available, the implementation of anticoagulant prophylaxis in patients with advanced cancer has yet to be more clearly defined. We aim to determine the incidence of lower extremity deep vein thrombosis (DVT) diagnosed by Doppler sonography (USD) in asymptomatic nonambulatory patients with advanced cancer. METHOD: In a prospective study, 44 nonambulatory cancer patients with grade 3-4 World Health Organization performance status, asymptomatic for lower extremity DVT, underwent bilateral venous USD studies of the lower extremities. Different risk factors and laboratory data were registered and correlated with the incidence of DVT. RESULT: Asymptomatic DVT was detected in 15 of 44 patients (34%, 95% CI, 0.21-0.49). Twenty-three percent of all patients had isolated deep calf vein thrombi and 11% of all patients had thrombi in the proximal veins. The only significant risk factor was the number of metastatic sites. DVT was found in 4 of 23 (17.4%) patients with one metastatic site as opposed to 11 of 21 (52.3%) with two or more sites (p < 0.01). CONCLUSION: USD of the lower extremities detected asymptomatic DVT in 34% of advanced nonambulatory cancer patients and may serve as an additional decision-making tool in the consideration of anticoagulant therapy for this specific population.

[Laboratory evaluation of lupus anticoagulant in Israel].

Lupus anticoagulants (LAC) are antibodies which are detected by a prolongation of phospholipid-dependent coagulation assays, and are associated with thrombotic events and pregnancy complications in patients with the antiphospholipid syndrome. The antiphospholipid syndrome is defined by arterial or venous thrombosis and/or pregnancy morbidity and by laboratory diagnosis of antiphospholipid antibodies. The laboratory diagnosis is based on LAC and/or anticardiolipin and/or anti-beta2-glycoprotein I antibodies present in plasma, on two or more occasions at least 12 weeks apart. ALthough the presence of LAC correlates best with thrombosis, the Laboratory testing of LAC is not well standardized. In this article, the Laboratory evaluation of LAC will be explained, including the different tests that are recommended by the Israeli Sub-committee of Thrombosis and Hemostasis Laboratories, the possibility to evaluate LAC in patients treated with antithrombotic therapy, and how to report and interpret the results.

Evaluation of ProC Global assay in women with a history of venous thromboembolism on hormonal therapy.

The risk of thrombosis in women increases significantly during treatment with hormonal therapy (HT). The aim of this study was to evaluate ProC Global assay in women with a history of venous thromboembolism (VTE) while using HT. Protein C activation time normalized ratio (PCAT-NR) levels were significantly lower in 32 women with a history of VTE while using HT (0.72 +/- 0.1) compared with 56 healthy controls without HT, matched by age at blood sampling (0.99 +/- 0.2) and 40 healthy controls with HT, matched by age and HT at VTE event (0.94 +/- 0.2) (P < 0.001 for both). PCAT-NR lower than the cut-off level of 0.8 was found in 23/32 (72%) patients compared with 5/56 (9%) age-matched controls (OR = 26, 95%CI: 7-106, P < 0.001) and 9/40 (22.5%) of HT-matched controls (OR = 9, 95%CI: 2.7-30, P < 0.001). Any thrombophilic risk factor was found in 20/32 (62.5%) of patients compared with 12/56 (21.4%) of agematched controls (OR = 6, 95%CI: 2.1-10, P < 0.001) and 12/40 (30%) of HT-matched controls (OR = 4, 95%CI: 1.3-11.8, P = 0.006). Out of the variables that are risk factors of VTE as age, HT or thrombophilic risk factor, ProC Global assay was found in the multivariate analysis - logistic regression, as the parameter that was the most associated with patient group [Exp(B) = 15.8, 95% CI: 4.2-59.0, P < 0.001]. In conclusion, abnormal PCAT-NR is associated with VTE in women using HT. ProC Global assay may potentially serve as a diagnostic tool for evaluating the risk of VTE in women prior to administration of HT.

Prospective evaluation of patients hospitalized with venous thromboembolism: comparison between cancer and non-cancer patients.

BACKGROUND: Little is known about the epidemiology of venous thromboembolism in hospitalized patients in Israel. Also, a direct comparison of the clinical and laboratory features between cancer and non-cancer patients has not yet been reported. OBJECTIVES: To investigate and compare the epidemiologic, clinical and laboratory characteristics of cancer and non-cancer patients hospitalized with venous thromboembolism in a large referral medical center in Israel. METHODS: Between February 2002 and February 2003, patients diagnosed at the Rambam Medical Center as suffering from VTE (deep vein thrombosis and/or pulmonary embolism), based on diagnostic findings on Doppler ultrasonography, spiral computed tomography scan or lung scan showing high probability for pulmonary embolism, were prospectively identified and evaluated. In addition, at the conclusion of the study period, the reports of spiral chest CT scans, performed during the aforementioned period in this hospital, were retrospectively reviewed to minimize the number of unidentified cases. Blood samples were drawn for evaluation of the coagulation profile. RESULTS: Altogether, 147 patients were identified and 153 VTE events diagnosed, accounting for 0.25% of all hospitalizations during the study period. The cancer group included 63 patients (43%), most of whom had advanced disease (63%). The most common malignancies were cancer of the lung (16%), breast (14%), colon (11%) and pancreas (10%). Of 122 DVT events (with or without pulmonary embolism) there were 14 upper extremity thromboses (12%). The most common risk factors for VTE, except malignancy, were immobilization (33%), surgery/trauma (20%) and congestive heart failure (17%). There was no difference in prevalence of various risk factors between cancer and non-cancer patients. During an acute VTE event, D-dimer levels were higher in cancer patients than non-cancer patients (4.27 +/- 4.04 vs. 2.58 +/- 1.83 mg/L respectively, P = 0.055). Relatively low values of activated protein C sensitivity ratio and normalized protein C activation time were observed in both cancer and non-cancer groups (2.05 +/- 0.23 vs. 2.01 +/- 0.33 and 0.75 +/- 0.17 vs. 0.71 +/- 0.22, respectively). These values did not differ significantly between the groups. CONCLUSION: The proportion of cancer patients among patients suffering from VTE was high. Their demographic, clinical and laboratory characteristics (during an acute event) were not different from those of non-cancer patients, except for higher D-dimer levels.

Inhalation of a Short-Acting ß2-Adrenoreceptor Agonist Induces a Hypercoagulable State in Healthy Subjects.

BACKGROUND: Catecholamine infusion elicits an increase in clotting factors and this increase has been attributed to stimulation of ß2-adrenorecptors (ß2AR). Accordingly, we tested the hypothesis that inhalation of a short-acting selective ß2AR agonist can induce a procoagulant state in healthy individuals. METHODS: We recruited 23 healthy volunteers (nine females; mean age: 26±0.8 years; body mass index: 24.7±0.5 kg/m2) and randomly allocated them into two groups, the ß2AR arm (seventeen subjects) and the saline arm (six subjects). Hemodynamics, plasma norepinephrine concentration, and procoagulant, anticoagulant, and fibrinolytic profiles of each participant were determined using specific assays before and after inhalation of either 2 mL nebulized normal saline or a mixture of 1 mL saline and 1 mL of salbutamol (5 mg salbutamol sulfate), a selective ß2AR agonist, which were delivered by a nebulizer over ten minutes. RESULTS: Saline inhalation had no effect on the procoagulant, anticoagulant and fibrinolytic profiles of the six healthy volunteer in the study's saline arm. Salbutamol inhalation caused (a) a significant increase in the activity or levels of the procoagulant factors; FVIII increased by 11±3% (p = 0.04), von Willebrand factor increased by 7±1% (p = 0.03), and (b) a significant decrease in the activated partial prothrombin time from 27.4±0.4 seconds to 25.5 ±0.5 seconds (p<0.001) in the 17 volunteers in the study's ß2AR arm. D-dimer and prothrombin fragments F1+2 were elevated by 200 ±90% and 505.0 ±300.0%, respectively. In addition, the activity of the anticoagulant protein C pathway (demonstrated by the protein C Global assay) decreased from 1.0±0.08 to 0.82±0.06 (p<0.001). Although plasma levels of tissue plasminogen activator decreased, all other indices of the fibrinolytic system did not change following salbutamol inhalation. CONCLUSION: We found that a single inhalation of salbutamol, a short-acting ß2AR agonist, activates the clotting system without affecting the fibrinolytic system. This induction of a procoagulant state in healthy subjects warrants further investigation in patients treated with these agents.

Modulation of systemic hemostatic parameters by enoxaparin during gestation in women with thrombophilia and pregnancy loss.

Recurrent pregnancy loss (PL) is associated with maternal thrombophilia and prophylaxis with low molecular weight heparin (LMWH) can improve pregnancy outcome in this setting. The aim of this study was to investigate the modulation of systemic hemostatic parameters by enoxaparin in women with recurrent PL and to evaluate plasmatic parameters that would potentially enable monitoring LMWH prophylaxis effect during pregnancy. Study group included 87 women with thrombophilia and PL treated with enoxaparin 40 mg daily vs. 40 mg twice daily. The control group comprised 40 women with normal pregnancies. Blood samples have been collected throughout the period starting at 5-10 weeks of gestation until 6-10 weeks postpartum. The determined plasmatic markers included: anti-Xa activity, total and free tissue factor pathway inhibitor (TFPI), D-dimer, prothrombin fragment 1+2 (PT1+2), activated protein C resistance (APC-SR) and free protein S. Successful pregnancy outcome was recorded in 70 (80.5%) women treated with enoxaparin, without correlation to enoxaparin dosage. Seventeen women (19.5%) had pregnancy loss at 16+/-7 (6-32) weeks of gestation. Anti-Xa levels at 10-15 weeks of gestation were higher (0.39+/-0.38 u/ml) in the successful pregnancy outcome group compared to the abortion group (0.22+/-0.2 u/ml). Prophylactic anti-Xa activity levels (0.28+/-0.13 u/ml) were documented from 15 weeks of gestation until delivery in the successful pregnancy outcome group. Significant increase in anti-Xa, total TFPI and free TFPI levels (P<0.001) was achieved after beginning of LMWH prophylaxis in successful pregnancy outcome group but not in the abortion group. D-dimer and PT1+2 levels appeared to be significantly increased while APC-SR and free protein S levels gradually decreased during pregnancy, with no difference between study groups. These results suggest that LMWH prophylaxis during pregnancy enables modulation of systemic hemostatic parameters via inhibition of factor Xa and increase in plasmatic total and free TFPI levels.

Hemostatic balance on the surface of leukemic cells: the role of tissue factor and urokinase plasminogen activator receptor.

BACKGROUND AND OBJECTIVES: The frequency of thrombotic complications is increased in patients with acute leukemia. Since coagulation processes take place on cell membranes, we hypothesized that expression of coagulation proteins on blast membrane could determine the hemostatic balance on the surface of leukemic cells and may correlate with thrombotic manifestations. DESIGN AND METHODS: Fifty-one consecutive patients with newly diagnosed acute leukemia were enrolled over an 11-month period. Twenty-five of the patients had acute myeloid leukemia (AML)-M(0-2), 11 had AML-M3, 6 had AML-M(4-5), and 9 acute lymphocytic leukemia (ALL). Peripheral blood and bone marrow were analyzed by flow-cytometry for tissue factor, protease-activated receptor 1, tissue factor pathway inhibitor, urokinase plasminogen activator receptor, and thrombomodulin. RESULTS: Regardless of the leukemia subtype, tissue factor was predominantly present on leukemic blast surfaces as compared to protease-activated receptor 1, tissue factor pathway inhibitor, urokinase plasminogen activator receptor and thrombomodulin and it was significantly elevated (mean 63+/-6%) in AML-M3 and AML-M(4-5) as compared to AML-M0(-2) and ALL (mean 37+/-4%, p<0.001). Likewise, urokinase plasminogen activator receptor expression was greater in AML-M(4-5) (49+/-11%) than in in AML- M(0-2), M3 and, ALL (mean 17+/-3%, p<0.001). Thrombotic manifestations were present in 13 out of 51 (26%) patients. The tissue factor to urokinase plasminogen activator receptor ratio was higher in patients with a thrombotic event than in patients without thrombotic events (16+/-4 vs. 6+/-2, p=0.042). INTERPRETATION AND CONCLUSIONS: This study demonstrates that tissue factor predominates on leukemic blast surface, particularly in M3 and M4-5 subtypes, while urokinase plasminogen activator receptor is increased on M4-5 blasts. The hemostatic balance on the blast surface may contribute to thrombotic manifestations in leukemic patients.

Predictive factors of bleeding and thrombosis during induction therapy in acute promyelocytic leukemia-a single center experience in 34 patients.

In this retrospective study, the hemorrhagic and thrombotic events are reported at presentation and during induction in 34 consecutive acute promyelocytic leukemia (APL) patients treated in a single referral center. The most consistent hemostatic abnormality was decreased fibrinogen level (<150 mg/dL) found in 21 patients (61%), partial thromboplastin time (PTT) was normal almost in all patients. A mildly prolonged prothrombin time (PT) was observed in 14 patients (44%). Median platelet count was 30.10(9)/L (range 3-191.10(9)/L). Life-threatening bleeding manifestations occurred in 10 patients (29%). By multivariate analysis, severe bleeding complications did not correlate with hemostatic parameters but did correlate with white cell count at presentation. Four patients (12%) had severe thrombotic events, two cerebral sagital sinus thrombosis, one pulmonary embolism, and one subclavian vein thrombosis. Two other patients had pseudotumor cerebri. Three out of six patients with thrombotic events were found to have thrombophilia. These results may suggest an association between thrombophilia and thrombosis in APL patients. Two patients suffered from combined severe bleeding and thrombosis. Hemostatic parameters are not helpful in predicting neither hemorrhage nor thrombosis.

Protein C global assay in the evaluation of women with idiopathic pregnancy loss.

Since the majority of thrombophilic defects in women with pregnancy loss are in the protein C pathway, we have prospectively determined the diagnostic value of a protein C global assay in 60 consecutive women with pregnancy loss compared to 61 controls. Protein C activation time normalized ratio (PCAT-NR) in pregnancy loss women was significantly lower than controls (0.74 +/- 0.16 vs. 0.99 +/- 0.2; P < 0.0001). PCAT-NR lower than cut off level of 0.8 were found in 42/60 (70%) of PL women compared to 7/61 (11%) of controls (OR = 18.0, 95% CI: 6.3-53.4, P < 0.0001). Cut-off level of 0.8 successfully identified all pregnancy loss women with abnormality in the protein C pathway (12 factor V Leiden, 7 APC-Resistance without factor V Leiden, 15 low levels of protein S and 1 of protein C). Moreover, PCAT-NR below 0.8 was documented in 15/29 (52%) of PL women without thrombophilic risk factor compared to 3/55 (5%) of controls (OR = 18.6, 95% CI: 4.2-95.2, P < 0.0001). These results suggest that ProC Global may be useful as a screening test for protein C pathway abnormalities and may serve as a new thrombophilic risk factor in women with pregnancy loss.