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Biomedical subjects

O Pradier

Publications and source records attributed to O Pradier.

At least 37 records · Page 2Linked to original sources
PubMed2001

Occurrence of the Asn45Ser mutation in the GPIX gene in a Belgian patient with Bernard Soulier syndrome.

Bernard Soulier Syndrome (BSS) is a rare inherited bleeding disorder caused by a defect in the glycoprotein (GP)Ib/IX/V complex. A patient with a bleeding problem was diagnosed as having BSS based on the prolonged bleeding time, the absence of ristocetin induced platelet aggregations, thrombocytopenia and the presence of giant platelets. Analysis of the platelets of the propositus, a 39-year-old Belgian female, by flow cytometry revealed a decreased expression of the GPIb/IX polypeptides. Western blotting confirmed these results and showed moreover that there was a decreased disulfide bridge formation between GPIb alpha and GPIb beta. After sequence analysis of the GPIb alpha, GPIb beta and GPIX genes, only a mutation in the GPIX gene at position 1826 (A-->G) was identified, changing Asn45-->Ser. Restriction analysis with Fnu4H1 demonstrated that the patient was homozygous for this mutation. As this Asn45-->Ser mutation in the GPIX gene was already found in four unrelated families, i.e. in a British, Austrian, Swedish and Finnish one, the occurrence of this mutation in a Belgian patient supports the hypothesis of Koskela et al. (1999) that the Asn45Ser mutation in GPIX appears to be an ancient mutation shared by northern and central European populations. Our present observation of a decreased disulfide bridge formation between GPIb alpha and GPIb beta shows that GPIX is not only needed for the correct assembly of the complex but might also be needed for the disulfide bridge formation between GPIb alpha and GPIb beta.

Adenosine Diphosphate↗
PubMed2001

In vitro response of human dermal fibroblasts to X-irradiation: relationship between radiation-induced clonogenic cell death, chromosome aberrations and markers of proliferative senescence or differentiation.

PURPOSE: To analyse the relationship between radiation-induced clonogenic cell death, chromosome aberrations and markers of proliferative senescence or differentiation. MATERIALS AND METHODS: Plateau-phase human dermal fibroblasts from 18 donors were irradiated with graded doses of 1-6 Gy 200kV X-rays. Cell survival was determined by a colony-forming assay. Markers of differentiation or senescence were: spontaneous and radiation-induced clonal differentiation, which was determined morphologically and by the cellular potential to proliferate in clonal culture, also single-cell beta-galactosidase (beta-gal) staining at pH 6.0; and the secretion of transforming growth factor-beta (TGF-beta1) into the culture medium. Chromosome aberrations were determined as genomic yields of dicentric chromosomes and the excess acentric fragments, scored in Giemsa-stained metaphases, and as partial yields of reciprocal translocations for chromosomes 4, 7 and 9 using the FISH method. RESULTS: A broad spread was found in the shapes of the survival curves, with SF2 ranging from 0.041+/-0.015 to 0.63+/-0.05. Radiation-induced clonal differentiation as well as the secretion of TGF-beta1 was elevated in radiosensitive samples. With respect to chromosome aberrations, a significant correlation was found between clonogenic survival and radiation-induced excess acentric fragments. CONCLUSIONS: In the fibroblast cell system, in vitro radiosensitivity is determined not only by processes directly involved in DNA-damage recognition and repair, but also by intracellular signalling cascades, which will lead to differentiation processes.

Cell Death↗
PubMed2001

Radiotherapy combined with simultaneous chemotherapy with mitomycin-C and 5-fluorouracil for inoperable head and neck cancer.

The feasibility and effectiveness of a combined chemoradiotherapy treatment modality for locally advanced head and neck cancer was tested in a phase II trial. From March 1995 to June 1998, 35 patients with advanced squamous cell carcinoma of the head and neck were treated with a continuous intravenous infusion of 5-fluorouracil (600 mg m-2 24 h-1 for Days 1 to 5 (120 h)) and mitomycin-C (10 mg m-2 intravenously) on Day 5 during the first week of radiotherapy and on Day 36. 31 patients had stage IV disease; 4 patients had stage III; and 1 patient had stage II. Patient ages ranged from 42-69 years (median 56.7 years). The tumours involved were as follows: oral cavity (n = 11); oropharynx (n = 14); hypopharynx/larynx (n = 10). Radiotherapy was delivered to a total dose of 70 Gy with conventional fractionation (2 Gy per fraction, five times a week). Chemotherapy was well tolerated and all patients received the intended dose. Mild nausea occurred in five patients. After a mean follow-up of 21 months (range 10-44 months), 8 (23%) patients remain alive. A complete response was seen in 28 (80%) patients. When a recurrence appeared, it was within the first year after treatment. 1- and 2-year overall survival rates were 46% and 23%, respectively. Grade 3 mucositis occurred in 17% of patients. Grade 1-2 thrombopaenia occurred in 3 (9%) patients, grade > 2 leukopaenia in 4 (11%) patients, and grade > or = 2 anaemia in 3 (9%) patients. We observed a treatment interruption of maximum 1 week for six patients owing to mucositis. Febrile neutropaenia or aplasia were not observed. The concomitant use of 5-fluorouracil, mitomycin-C and radiotherapy in locally advanced head and neck carcinoma is well tolerated in this group of patients. This protocol showed good locoregional response with a very low toxicity profile.

Adult↗
PubMed2000

Early inflammatory response after elective abdominal aortic aneurysm repair: a comparison between endovascular procedure and conventional surgery.

OBJECTIVE: To determine the nature of and to compare the inflammatory responses induced by (1) endovascular and (2) conventional abdominal aortic aneurysm (AAA) repair. MATERIAL AND METHODS: Twelve consecutive patients undergoing elective infrarenal AAA repair were prospectively studied. Seven patients were selected for endovascular procedures (the EAAA group); five patients underwent open surgery (the OAAA group). Three control patients undergoing carotid thromboendarterectomy were also included. Serial peripheral venous blood samples were collected preoperatively, immediately after declamping or placement of the endograft, and at hours 1, 3, 6, 12, 24, 48, and 72. Acute phase response expression of peripheral T lymphocyte and monocyte activation markers and adhesion molecules (flow cytometry), soluble levels of cell adhesion molecules (enzyme-linked immunosorbent assay), cytokine (tumor necrosis factor alpha, interleukin-6, and interleukin-8) release (enzyme-linked immunosorbent assay), and liberation of complement products (nephelometry) were measured. RESULTS: Regarding acute phase response, the EAAA and OAAA groups showed significant increases in C-reactive protein (P <.001 and P =.001), body temperature (P =.035 and P =.048), and leukocyte count (P <.001 and P <.001). Similar time course patterns were observed with respect to body temperature (P =.372). Statistically significant different patterns were demonstrated for C-reactive protein (P =.032) and leukocyte count (P =.002). Regarding leukocyte activation, a significant upregulation of peripheral T lymphocyte CD38 expression was observed in the OAAA group only (P =.001). Analysis of markers such as CD69, CD40L, CD25, and CD54 revealed no perioperative fluctuations in any group. Regarding circulating cell adhesion molecules, the EAAA and OAAA groups displayed significant increases in soluble intercellular adhesion molecule-1 (P =.003 and P =.001); there was no intergroup difference (P =.193). All groups demonstrated high soluble von Willebrand factor levels (P =.018, P =. 007, and P =.027), there being no differences in the patterns (P =. 772). Otherwise, soluble vascular cell adhesion molecule-1, soluble E-selectin, and soluble P-selectin did not appear to vary in any group. Regarding cytokine release, although a tendency toward high tumor necrosis factor alpha and interleukin-8 levels was noticed in the EAAA group, global time course effects failed to reach statistical significance (P =.543 and P =.080). In contrast, interleukin-6 showed elevations in all groups (P =.058, P <.001, and P =.004). Time course patterns did not differ between the EAAA and OAAA groups (P =.840). Regarding complement activation, the C3d/C3 ratio disclosed significant postoperative elevations in the EAAA and OAAA groups (P =.013 and P =.009). This complement product release was reduced in the EAAA group (P <.001). CONCLUSIONS: The current study indicated that both endovascular and coventional AAA repair induced significant inflammatory responses. Our findings showed that there were no large differences between the procedures with respect to circulating cell adhesion molecule and cytokine release. Moreover, the endoluminal approach produced a limited response in terms of acute phase reaction, T lymphocyte activation, and complement product liberation. This might support the concept that endovascular AAA repair represents an attractive alternative to open surgery. Given the relatively small sample size, further larger studies are required for confirmation of our observations.

Aged↗
PubMed1999

Inhibition of the CD40 pathway of monocyte activation by triazolopyrimidine.

Blockade of the CD40/CD40L pathway of monocyte/macrophage activation represents a promising strategy for the treatment of several inflammatory disorders. So far, most pharmacological agents developed for that purpose target CD40L (CD154) expressed on activated T cells. Herein, we provide evidence that triazolopyrimidine, a chemical compound primarily developed for the prevention of arterial thrombosis, strongly inhibits the response of human monocytes to CD40 ligation. First, we found that triazolopyrimidine inhibits the production of IL-12, TNF-alpha, and IL-6 by monocytes activated by coculture with fibroblasts transfected with the CD40L gene as well as the induction of procoagulant activity at their membrane. This was related to a decreased expression of CD40 on monocytes exposed to triazolopyrimidine, an effect that was already apparent at the mRNA level. Furthermore, the addition of triazolopyrimidine to monocytes cultured with IL-4 and GM-CSF prevented their differentiation into fully competent dendritic cells (DC) as DC differentiated in the presence of triazolopyrimidine expressed less CD40 at their surface and were profoundly deficient in the production of IL-12 upon exposure to CD40L transfectants. We conclude that triazolopyrimidine strongly inhibits the CD40 pathway of monocyte activation at least in part by downregulating the gene expression of CD40.

Blood Coagulation Factors↗
PubMed1999

Effects of paclitaxel in combination with radiation on human head and neck cancer cells (ZMK-1), cervical squamous cell carcinoma (CaSki), and breast adenocarcinoma cells (MCF-7).

BACKGROUND AND PURPOSE: The anticancer drug paclitaxel, a natural product from Taxus brevifolia, is a microtubule-stabilising agent, which has been shown to block different cells in the G2/M phase of the cell cycle and so modulate their radioresponsiveness. We investigated the radiosensitizing potential of paclitaxel in human head and neck cancer cells (ZMK-1), in cervical squamous cell carcinoma cells (CaSki) and in breast adenocarcinoma cells (MCF-7). METHODS: ZMK-1 cells were incubated with paclitaxel for 3, 9, or 24 h before irradiation. ZMK-1-, CaSki- and MCF-7 cells were incubated with paclitaxel for 24 h after irradiation. The paclitaxel concentration (70 nM, 7 nM, 0.7 nM) was chosen to obtain equivalent toxicity at the different incubation times (3 h, 9 h, 24 h respectively). Radiation doses were from 0 to 8 Gy. Cell survival was measured by a standard clonogenic assay after a 9-day incubation. Flow cytometry was used to measure the capacity of paclitaxel to cause accumulation of cells in the G2/M phase of the cell cycle. RESULTS: Paclitaxel alone was cytotoxic in a time- and concentration-dependent manner. Up to 36% of the ZMK-1 cells accumulated in G2/M after treatment for 24-36 h. If the cells were incubated with paclitaxel before irradiation the isoeffect enhancement ratios for ZMK-1 cells, determined at the 37% survival level, were 0.81, 1.48 and 1.15 for 3-h, 9-h, and 24-h pre-incubations respectively. For a paclitaxel incubation of 24 h after irradiation, the isoeffect enhancement ratios, determined at the 37% survival level, were 0.72, 0.76 and 1.2 for the ZMK-1. CaSki, and MCF-7 cells respectively. CONCLUSION: In the three cell lines no radiosensitizing effect of paclitaxel could be demonstrated unambiguously. The use of asynchronized cells or the support of cellular repair mechanisms while the cells are blocked in G2/M could partly explain the results.

Adenocarcinoma↗
PubMed1999

Radiosensitizing effect of natural and recombinant beta-interferons in a human lung carcinoma in vitro.

PURPOSE: The enhancing effect of natural interferon-beta (n-IFN-beta) or recombinant interferon-beta (r-IFN-beta) on radiation damage in tumor cells has been evaluated in several sudies. It is not clear whether the different forms of IFN-beta available today are equally efficient in modulating the intrinsic radiosensitivity of tumor cells. The purpose of this study was to compare the radiosensitizing effect of n-IFN-beta, r-IFN-beta1a, and r-IFN-beta1b in one cancer cell line. METHODS: The A549 lung-cancer cell line was grown as a monolayer culture and incubated for 24 h with n-IFN-beta (Fiblaferon), r-IFN-beta1a (Betaserin), or r-IFN-beta1b (Betaferon). Thereafter, the cultures were irradiated with single graded doses of 0, 1, 2, 4, and 6 Gy. Cellular survival was counted in a colony-forming assay at 10 days after treatment. Survival curves were established using the linear quadratic model. Statistical comparison of the survival data was performed using Student's t-test for each dose point. Interactions of IFN-beta and radiation were evaluated using isobologram analysis. RESULTS: All three types of IFN-beta enhanced the radiation sensitivity of A549 cells in a similar way as shown in the alteration of the survival curves and the isobologram analysis. The isoeffective concentration of r-IFN-beta1b was 2.7-fold higher than that of r-IFN-beta1a or n-IFN-beta. All three interferons increased the alpha-component of the survival curves in a concentration-dependent way, suggesting an influence on repair of radiation damage. The maximal sensitizing enhancement ratio (SER) obtained with n-IFN-beta or r-IFN-beta1a at 3000 IU/ml was 1.66 and 1.51, respectively. The highest SER, obtained with r-IFN-beta1b, at 8000 IU/ml was 1.93. CONCLUSIONS: All three interferons tested can equally modify the intrinsic radiosensitivity of A549 cells. The isoeffective concentration of r-IFN-beta1b is 2.7-fold that of n-IFN-beta or r-IFN-beta1a.

Cell Division↗
PubMed1999

Accuracy of alignment in breast irradiation: a retrospective analysis of clinical practice.

The objective of the study was to determine the accuracy of patient positioning in radiotherapy for breast cancer. Portal images were obtained using a fast electronic megavoltage radiotherapy imaging system in 30 cases of breast cancer. Quantitative analysis of 530 megavolt portal images and comparison with 30 digitized simulation films were performed. Five linear measurements were taken for each simulation and verification film. Central lung distance (CLD) is the distance from the dorsomedial beam edge to the inner thoracic wall in the central plane of the beam. Cranial lung distance (CrLD) is the distance from the dorsomedial beam edge to the inner thoracic wall in the plane of the beam at 4 cm from the central plane. Central beam edge to skin distance (CBESD) is the distance from the skin to the ventrolateral beam edge in the central plane of the beam. The central irradiated width (CIW) is defined as the distance from the dorsomedial beam edge to the skin. The craniocaudal distance (CCD) is defined as the distance from a particular landmark to the caudal field border. Concerning patient position in the field, mean standard deviations of the difference between simulation and treatment images were 3.9 mm for the CLD, 3.2 mm at +4 cm, 3.6 mm for the CIW, 3.3 mm for the CBESD, 3.8 mm for the CCD. In 90% of all set-up for treatment, errors were less than 1 cm. The variation of the CLD was the largest set-up error. This parameter is clinically the most significant. Future treatment delivery should be improved by introducing patient positioning devices such as thermoplastic shells. The electronic portal imaging device (EPID) appears to be an adequate tool to study the accuracy of treatment set-ups like this.

Breast Neoplasms↗
PubMed1998

Radiation rendered more cytotoxic by fludarabine monophosphate in a human oropharynx carcinoma cell-line than in fetal lung fibroblasts.

PURPOSE: Fludarabine monophosphate (fludarabine-P) is a relatively new drug in the treatment of different haematological diseases. The mechanism of action also implies a possible role of this drug as a radiosensitizer. Up to now no in vitro investigations dealing with radiosensitizing effects of fludarabine-P in carcinoma cell lines and fibroblasts have been published. The aim of our studies was to analyse the cytotoxic and radiosensitizing effects of different dosages and application schedules of fludarabine-P in a human squamous carcinoma cell line of the oropharynx (ZMK-1) and of fetal lung fibroblasts (MRC-5) in vitro. Possible mechanisms of interaction of fludarabine-P and radiation were investigated. METHODS: ZMK-1 and MRC-5 cells were cultured under standard conditions with different concentrations of fludarabine-P in combination with escalating doses of radiation. Cytotoxic effects were measured by colony-forming assays. Induction and rejoining of radiation-induced DNA double-strand breaks after incubation with fludarabine-P were measured using constant-field gel electrophoresis. Incubation times for rejoining varied from 0 h to 24 h. RESULTS: Fludarabine-P showed a radiosensitizing activity in ZMK-1 tumour cells and MRC-5 fibroblasts. The observed effects depended on the concentration and the incubation time. The largest effect was demonstrable for an incubation of 5 days, which started shortly before irradiation, whereas an incubation solely before irradiation did not have a clear effect on the cellular survival. The sensitizer enhancement ratio, at the 10% survival level, in the ZMK-1 cells was 2.2 in comparison to 1.6 in MRC-5 cells. The analysis of the interaction of fludarabine-P and ionising radiation by means of the isobologram approach, revealed an overadditive effect in the tumour cell line and an additive effect in the lung fibroblasts. Fludarabine-P did not modify the rejoining of radiation-induced DNA double-strand breaks in either cell line. CONCLUSIONS: We conclude that fludarabine-P in clinically attainable doses is a strong radiosensitizer in ZMK-1 cells and has a lower activity in the MRC-5 fibroblasts in vitro. The radiosensitization of fludarabine-P seems to be over additive in the malignant cells and additive in normal fetal fibroblasts. This would indicate that fludarabine-P might enhance the therapeutic ratio of radiation. Further investigations are warranted to identify the potential of this drug as a radiosensitizer in vivo and to elucidate the mechanism of interaction of the drug and radiation.

Carcinoma, Squamous Cell↗
PubMed1998

Overexpression of Bcl-2 in Kaposi's sarcoma-derived cells.

The pathogenesis of Kaposi's sarcoma (KS), a tumor of probable vascular origin, remains an enigma. It is still unclear whether KS is a true malignancy or whether it represents a reactive polyclonal process. Using both an immunohistochemical and an immunoblot approach, we found that cells derived from KS lesions express significant levels of Bcl-2, a protein known to prolong cellular viability and to antagonize apoptosis. Bcl-2 expression was found in AIDS-related KS-derived cells, as well as in cells derived from iatrogenic and sporadic KS, indicating that Bcl-2 upregulation may be important in the pathogenesis of KS regardless of its epidemiologic form. By contrast, fibroblasts and dermal microvascular endothelial, cells which are the probable vascular progenitors of KS cells, expressed low levels of Bcl-2. The expression of Bcl-2 in KS-derived cells was associated with a long-term survival in serum-deprived conditions, a situation that has been shown to induce apoptosis in various cell types. Incubation of fibroblasts or of dermal microvascular endothelial cells with KS cell-free supernatants did not enhance Bcl-2 expression, suggesting that Bcl-2 expression is not mediated by an agent released by KS cells. Analogously, KS supernatants failed to promote the viability of fibroblasts and of dermal microvascular endothelial cells cultured in serum-free conditions. Our findings suggest that the spindle cells derived from KS have a survival advantage and may adequately represent the tumor cells of KS.

Cell Survival↗
PubMed1998

Evaluation of two D-Dimer assays in the diagnosis of venous thromboembolism.

A qualitative (Instantia) and a quantitative (VIDAS D-Dimer) D-Dimer test have been evaluated and compared with an ELISA method (Asserachrom D-D) in a population of 74 patients suspected of presenting a deep vein thrombosis. Among the thirty-two patients presenting a deep vein thrombosis on phlebography, there were 16 (50%) proximal vein thrombosis and 16 (50%) distal vein thrombosis. Sensitivity and negative predictive value for proximal thrombosis were 100% in all three tests. For distal vein thrombosis, sensitivity and negative predictive value were respectively 81% and 81% for Asserachrom D-DI 75% and 76% for VIDAS D-Dimer and 63% and 82% for Instantia. In conclusion, this study shows that these D-Di assays are a useful tool to exclude proximal vein thrombosis, at least for patients who are not under anticoagulant therapy.

Adult↗
PubMed1998

Subcutaneous panniculitis-like T-cell lymphoma: further evidence for a distinct neoplasm originating from large granular lymphocytes of T/NK phenotype.

We report the case of a 20 year-old caucasian woman who presented a primary subcutaneous panniculitis-like T-cell lymphoma (SPTCL) as an invasive tumor of the chest wall. Herein, the neoplastic cells were found to express a CD3+CD8+ phenotype but also displayed variably the natural killer (NK)-associated antigens CD56 and CD57 as well as granzyme B. On cytological examination, these cells showed a large granular lymphocyte (LGL)-like morphology with presence of azurophilic granules in their cytoplasm. Electron dense and membrane bound granules like those found in cytotoxic T lymphocytes (CTL) were also demonstrated by electron microscopy. Neither rearrangement of the T-cell receptor subunits nor Epstein-Barr virus (EBV) genome was observed at the molecular level. The LGL-like features of the neoplastic cells found in this case and the presence of NK-associated antigens provide additional support to the cytotoxic derivation of most SPTCL.

Adult↗
PubMed1998

CD40 engagement on endothelial cells promotes tissue factor-dependent procoagulant activity.

The CD40 molecule expressed on endothelial cells has been shown to transduce activation signals resulting in upregulation of adhesion molecules. Herein, we studied the impact of CD40 engagement on the induction of tissue factor (TF)-dependent procoagulant activity (PCA) at the surface of human umbilical vein endothelial cells (HUVECs). First, we found that co-incubation of HUVECs with 3T6 fibroblasts transfected with the CD40L gene (3T6-CD40L) resulted in a clear induction of PCA which was not observed with control untransfected fibroblasts. The specificity of this finding was established by inhibition experiments using monoclonal antibodies (mAbs) blocking CD40 or CD40L. PCA induced by CD40 ligation was TF-related as it was not observed in factor VII-deficient plasma and was associated with the accumulation of TF mRNA. To investigate the role of CD40/CD40L interactions in the induction of endothelial cell PCA by lymphocytes, interferon (IFN)-gamma-stimulated EC were incubated with T cells in the absence or presence of anti-CD40 or anti-CD40L mAb. The 60-70% inhibition of PCA induced by these mAbs but not their isotype-matched control indicated that the CD40 pathway is involved in the induction of PCA resulting from interactions between activated HUVECs and T cells. We conclude that activation signals elicited by CD40 engagement on endothelial cells result in the induction of TF-dependent PCA. The CD40/CD40L pathway might therefore be involved in the development of prothrombic states during diseases associated with endothelial cell and T cell activation.

Blood Coagulation↗
PubMed1997

Morphologic and phenotypic changes of the leukemic cells in a case of marginal zone B-cell lymphoma.

A particular case of marginal zone B-cell lymphoma (MZBCL) presenting with leukemic lymphocytes is reported. In the present observation, the leukemic cells not only displayed a remarkable morphological fluctuation but also had an unusual phenotype, changing with time. These phenotypic features, which have been functionaly investigated by in vitro assays, might simply reflect an activation state depending on the microenvironment. Because of its disconcerting similarities with hairy cell leukemia (HCL) and splenic lymphoma with villous lymphocytes (SLVL), this case relaunches the debate about whether close relationships might exist between the splenic marginal zone, SLVL and HCL.

Antigens, CD19↗
PubMed1996

Monocyte procoagulant activity induced by in vivo administration of the OKT3 monoclonal antibody.

The first injection of OKT3 in kidney transplant recipients activates the common pathway of coagulation. This may result in early thrombosis of graft vessels. To this day, the cells involved in this phenomenon have not been identified. The aim of this study was to investigate whether circulating monocytes participated in this OKT3-induced coagulopathy. The procoagulant activity (PCA) of circulating monocytes rose from (mean +/- SEM) 0.15 +/- 0.02 mU/mL to 0.40 +/- 0.05 mU/mL at 3 hours (P = .002) and 0.56 +/- 0.21 at 5 hours (P = .045) after the initial OKT3 injection. These monocytes displayed increased tissue factor expression at the same moments (mean flourescence intensity: 14 +/- 2 before OKT3 injection versus 54 +/- 14 at 3 hours, P = .008 and 34 +/- 7 at 5 hours, P = .01). Tissue factor mRNA was detected in blood by reverse transcriptase-polymerase chain reaction as early as 2 hours after OKT3 administration. The circulating monocytes also displayed a steady increase in membrane expression upregulation of ICAM-1, CD29, CD11b, and CD11c. In vitro experiments showed that OKT3 as well as 2 mitogenic, humanized anti-CD3 antibodies potently induced monocytic PCA whereas the 4 nonmitogenic anti-CD3 antibodies tested were over 1,000-fold less potent than OKT3. We conclude that (1) OKT3 induces in vivo tissue factor gene upregulation and membrane expression resulting in increased PCA of circulating monocytes; and (2) nonmitogenic anti-CD3 antibodies seem devoid of significant procoagulant properties.

Blood Coagulation↗
PubMed1996

CD40 engagement induces monocyte procoagulant activity through an interleukin-10 resistant pathway.

Interactions between membrane-bound molecules were previously shown to be involved in the induction of tissue factor-dependent monocyte procoagulant activity (PCA) by activated T cells. To investigate the potential role of the CD40/CD40 ligand (CD40L) pathway in this process, we first determined the effects of blocking anti-CD40 or anti-CD40L monoclonal antibodies (mAb) on the development of monocyte PCA during mixed lymphocyte reaction (MLR) between allogeneic peripheral blood mononuclear cells (PBMC). The strong inhibitory effect exerted by both mAb (mean percentages of inhibition: 88 and 91% for anti-CD40 and anti-CD40L mAb, respectively) indicates that CD40/CD40L interactions are required for the induction of PCA in MLR. These data led us to measure monocyte PCA after incubation of PBMC or purified monocytes with a stimulating anti-CD40 mAb (BL-C4) or with 3T6 fibroblasts transfected with the gene encoding CD40L. In both systems, we found that CD40 engagement strongly induced monocyte PCA which was related to tissue factor expression as shown by flow cytometric analysis. Finally, we observed that recombinant interleukin (IL)-10, which inhibits lipopolysaccharide-induced PCA, did not significantly influence CD40-dependent PCA. We conclude that CD40 engagement on monocytes induces tissue factor-dependent PCA through an IL-10-resistant pathway. These findings have implications for the control of coagulation events triggered by interactions between T cells and monocytes.

Antibodies, Monoclonal↗
PubMed1996

Role of CD18-dependent and CD18-independent mechanisms in the increased leukocyte adhesiveness and in the variations of circulating white blood cell populations induced by anti-CD3 monoclonal antibodies.

Anti-CD3 antibodies induce a quick and profound depletion of peripheral blood mononuclear cells (PBMCs) that is not well understood. We studied the effect of OKT3, a mouse monoclonal antibody against the human CD3 complex, on the in vitro adhesion of human PBMCs to monolayers of fresh and fixed human umbilical vein endothelial cells (HUVECs). OKT3 induced an increased adhesiveness of PBMCs. This phenomenon was blocked with anti-CD18 antibodies, indicating the participation of beta 2 integrins. As this increased adhesiveness could explain the lymphopenia by adhesion of PBMCs to endothelial cells and their sequestration in some peripheral vascular beds, we studied the effect of anti-CD18 antibodies in vivo on mice injected with 145/2C11, a hamster monoclonal antibody against murine CD3. Mice treated with 145/2C11 presented with a transient granulocytopenia and a sustained reduction in PBMCs. A monoclonal anti-CD18 antibody prevented the granulocytopenia but had no effect on the drop in PBMCs. Consequently, the in vivo depletion of PBMCs after administration of an anti-CD3 monoclonal antibody involves CD18-independent mechanisms, while the transient drop in polymorphonuclear cells appears to be CD18-dependent.

Adult↗