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J Sampol

Publications and source records attributed to J Sampol.

At least 55 records · Page 3Linked to original sources
PubMed1997

Quantitative analysis of leukocyte membrane antigen expression on human fetal and cord blood: normal values and changes during development.

We studied the antibody binding capacity (ABC) of various cell-surface antigens in normal human fetuses and term neonates on lymphocyte, monocyte, and polymorphonuclear (PMN) cells by quantitative flow cytometry also designated by quantimetry. Analysis of changes of expression level on these leukocytes during the developmental process was also investigated. The results indicated that the ABC values of most studied markers change during the maturational process. The ABC of lymphocyte-associated antigens studied such as CD5 and CD7 showed only a decrease from fetus to adult, whereas according to the type of molecule on monocyte and PMN there was either an increase or a decrease of ABC values dependent on the stage of the developmental process, from fetus to neonate or from neonate to adult. However, the ABC values of leukocyte membrane antigens such as CD16, CD46, and CD55 on all leukocytes and CD11b, CD11c, and CD35 on myeloid cells did not change. Their expression level was already mature in fetuses compared with adult cells. In addition, in this quantimetric approach, the analysis of the results for CD11a and CD8 suggested that the changes of CD11a expression level on lymphocyte subsets can depend on one mechanism, whereas there are probably at least two for CD8. Furthermore, the expression patterns of CD5, CD7, and CD11a change during maturation. We concluded that, even if the neonate response pattern to immunological challenge differs from an adult and this is based primarily on the relative numbers and functional activity of lymphocyte T subsets (especially TH1/TH2) and their cytokine profiles, these quantitative and qualitative phenotypical differences might also contribute to explain the functional peculiarities of leukocyte fetal and cord blood cells. All these findings support the notion of immaturity and maturity of ABC expression.

Adult↗
PubMed1997

Thrombosis in congenital deficiencies of AT III, protein C or protein S: a study of 44 children.

Congenital deficiency in coagulation inhibitors is a cause of hereditary thrombotic disease. The severity of symptoms is variable and depends on the type of deficit. In this paper, 44 children suffering from deep venous thrombosis, with a mean age of 5 years, were studied. A search for Lupus anticoagulant (LA) and coagulation inhibitor deficiency showed: 3/44 cases (6.8%) had protein S deficiency, 2/44 cases (4.5%) had protein C deficiency, 1/44 cases (2.3%) had deficiencies in both protein C and S; no cases of AT III deficiency and LA was positive in 2/44 cases (4.5%). Only 1 case of APC resistance out of 13 studied was found. Four family studies were performed and confirmed the congenital origin of the disorder.

Adolescent↗
PubMed1997

Rickettsia conorii infection enhances vascular cell adhesion molecule-1- and intercellular adhesion molecule-1-dependent mononuclear cell adherence to endothelial cells.

Leukocyte adherence to the endothelium is an essential component of the inflammatory response during rickettsial infection. In vitro, Rickettsia conorii infection of endothelial cells enhances the expression of adhesive molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in a time- and dose-dependent manner. Rickettsial lipopolysaccharide does not seem to be involved, because polymyxin B does not reduce their expression. The intracellular presence of the organism and de novo host protein synthesis are required for expression of cell adhesive molecules, since rickettsial inactivation by formol and pretreatment of cells with cycloheximide inhibits an increase in expression. The contribution of interleukin-1alpha (IL-1alpha) to this endothelial adhesive phenotype was shown by inhibitory experiments 8 and 24 h after infection with IL-1 receptor antagonist and IL-1alpha blocking antibodies. Enhanced adherence of mononuclear cells to infected endothelial cells involved VCAM-1- and ICAM-1-dependent mechanisms at the late phase of the inflammatory response. This endothelial adhesive phenotype may constitute a key pathophysiologic mechanism in R. conorii-induced vascular injury.

Animals↗
PubMed1997

Immunologic phenotype of cultured endothelial cells: quantitative analysis of cell surface molecules.

Endothelial cells express a wide spectrum of surface molecules involved in multiple vascular functions. We quantitatively determined an extensive immunologic phenotype of endothelial cells through a large panel of antibodies directed against i) well-known endothelial molecules CD31, CD34, CD49b, e, f, CD51, CD54, CD55, CD62E and P, CD105, CD106, HLA class I and HLA class II; ii) molecules defined by monoclonal antibodies newly clustered during the 6th workshop of Human Leukocyte Differentiation Antigen (HLDA) CD109, CD140b, CD141, CD142, CD143, CD144, CDw145, CD146 and CD147; iii) molecules defined by unclustered monoclonal antibodies. The expression of these molecules was quantified on human umbilical vein endothelial cells (HUVEC) cultured in resting conditions and after stimulation with IL-1beta (10 U/ml), TNF-alpha (10 ng/ml) and phorbol myristate acetate (60 ng/ml). Some molecules were constitutively expressed, and others were negative, which served to determine the basal phenotype. After cell stimulation, the molecules showed weak or strong expression modulation, leading to the definition of an activated phenotype. Changes in the kinetics and the amplitude of expression served to characterize poorly defined molecules and may be useful to determine their physiologic role. Also, we compared the phenotypes of endothelial cell lines EA.hy 926 and ECV 304 to that of HUVEC to assess their reliability as an endothelial cell model. Each cell line displayed a specific repertoire of molecules expressed at different levels, which could have significant implications for cell line behavior as endothelial cells.

Antigens, CD↗
PubMed1997

CD4+ T-cell lymphopenia in Q fever endocarditis.

Valvular endocarditis is the most serious complication of chronic Q fever, an infectious disease due to Coxiella burnetii. Although its pathogenesis is poorly understood, the role of the immune system has been evoked. The aim of this study was to investigate lymphocyte subsets in the peripheral blood of infected patients by analyzing the distribution of T- and B-lymphocyte subsets. Since various infectious diseases have been found to be associated with modified antigen expression, we also measured the antigen density of the main lymphocyte markers by quantitative flow cytometry. The absolute values of CD3+ T cells and CD19+ B cells were lower in infected subjects than in controls. The decrease in the CD4+ T-cell count was more pronounced than that in the CD8+ T-cell count, leading to a significantly lower CD4/CD8 ratio in patients. The decreases in CD4+ T cells and CD19+ B cells were correlated with levels of C. burnetii-specific immunoglobulin G, showing that CD4+ lymphopenia is related to the activity of chronic Q fever. Quantitation of antigen expression on lymphocytes showed that CD3, CD4, CD8, and CD19 were expressed similarly in patients and controls. In contrast, CD2 and CD11a expression levels, which are both related to naive and memory phenotypes, were modified in patients. The study of CD45RO and CD45RA expression by CD4+ T cells provided evidence that lymphopenia preferentially affected unprimed lymphocytes.

Adult↗
PubMed1997

Evaluation of sensitivity and specificity of a standardized procedure using different reagents for the detection of lupus anticoagulants. The Working Group on Hemostasis of the Société Française de Biologie Clinique and for the Groupe d'Etudes sur I'Hémostase et la Thrombose.

This study was designed to test the sensitivity and specificity of a combination of 3 phospholipid-dependent assays performed with various reagents, for the detection of lupus anticoagulant (LA). Plasmas containing an LA (n = 56) or displaying various confounding pathologies [58 intrinsic pathway factor deficiencies, 9 factor VIII inhibitors, 28 plasmas from patients treated with an oral anticoagulant (OAC)] were selected. In a first step, the efficiency of each assay and reagent was assessed using the Receiving Operating Characteristic (ROC) method. Optimal cut-offs providing both sensitivity and specificity > or = 80% were determined. The APTT assay and most of the phospholipid neutralization assays failed to discriminate factor VIII inhibitors from LA. In a second step, using the optimal cut-offs determined above, the results of all the possible combinations of the 3 assays performed with 4 different reagents were analyzed. Thirteen combinations of reagents allowed > or = 80% of plasmas of each category (LA, factor deficiency or OAC) to be correctly classified (3/3 positive test results in LA-containing plasmas and 0/3 positive results in LA-negative samples).

Evaluation Studies as Topic↗
PubMed1996

Quantitative analysis of leukocyte membrane antigen expression: normal adult values.

In this paper the normal ranges of the expression of various differentiation antigens, referred to by their cluster of differentiation (CD) numbers, are described on the lymphoid, monocytic, and polymorphonuclear (PMN) blood populations in normal healthy individuals. The values expressed as antibody binding capacity per cell (ABC/cell) are related to the density of antigenic molecules expressed by these cells. These values have been quantitated by the quantitative indirect immunofluorescence (QIFI) test which renders the ABC/ cell values for the different antigens directly comparable and defines a "league table," i.e., an enumeration of antigen expression on the three main cell types studied. The values for occasional antigen that are expressed differently in adults and the elderly or men and women (CD5, CD8, and CD18) are also shown. Furthermore, the QIFI test is used in two-color immunofluorescence for defining the subset heterogeneity within the T lineage for the CD2 and CD7 antigen within the separately analyzed CD45RA and CD45RO subsets. These quantitative immune phenotype analyses, also referred to as quantimetry, show variations in ABC values if different monoclonal antibodies (MAbs) are used, although these differences are frequently minor. Therefore, using whole blood and well-characterized MAbs, we established values of antigen density in normal adults which can be regarded as control values for the various pathological conditions where CD antigen expression may be altered.

Adult↗
PubMed1996

Identification of the S-Endo 1 endothelial-associated antigen.

We have recently described a monoclonal antibody, S-Endo 1, recognizing a molecule constitutively expressed in all types of human endothelial cells. We showed that this protein around 118 kDa and located at the endothelial cell-cell junction presented sequence identity with MUC18 described as a tumor marker in human melanoma. The difference in antibodies immunoreactivity and antigen molecular weight heterogeneity observed between various cell types strongly suggested S-Endo 1 antigen isoforms expression.

Amino Acid Sequence↗
PubMed1996

Monoblastic leukemia in an HIV-infected patient: absence of viral expression in RNA blasts.

A small number of patients seropositive for the human immunodeficiency virus (HIV) have been reported as developing acute non-lymphoblastic leukemia (ANLL). In the cases previously published, the authors never reported a study of the link joining HIV infection and leukemia. We describe here the case of a 41-year-old HIV positive patient who developed ANLL (FAB classification M5). Using molecular techniques, we looked for a direct link between these two co-existing diseases. We showed the absence of HIV expression in the malignant clone, suggesting that the association of ANLL and Acquired Immune Deficiency Syndrome is not a direct consequence of the myeloid precursors infection. Nevertheless a relationship may exist through a disorganization of the bone marrow micro-environment.

Adult↗
PubMed1996

S-Endo 1, a pan-endothelial monoclonal antibody recognizing a novel human endothelial antigen.

A murine monoclonal antibody (mAb) S-Endo 1 has been produced to detect circulating endothelial cells detached from blood vessels in pathological conditions. We have demonstrated that the associated-antigen (S-Endo 1 Ag) was highly expressed on human vascular structure irrespective of tissue origin or vessel caliber. Its expression was not restricted to endothelium, since it was also detected at low level on smooth muscle cells, stroma cells and follicular dendritic cells. But its absence on hematopoietic cells made S-Endo 1 a helpful reagent to specifically discriminate endothelium from hematopoietic tissues. Biochemical characterization showed that S-Endo 1 recognizes a monomeric structure of approximately 118 kDa on cultured endothelial cells. S-Endo 1 was submitted to the 5th International Workshop (Boston, 1993) and did not cluster in any of the old or new endothelial clusters discussed at the conference, indicating its unique reactivity. Together with the data presented in this paper, this suggested that S-Endo 1 defines a previously undescribed endothelial molecule.

Animals↗
PubMed1995

Serum erythropoietin and reticulocyte maturity index after renal transplantation: a prospective longitudinal study.

Improvement in erythropoiesis following renal transplantation (RT) was assessed in 74 consecutive patients by serial measurements of serum erythropoietin (EPO), hematocrit, absolute reticulocyte count (ARC) and serum creatinine during the first month after RT. The reticulocyte maturity index (RMI) which provides an objective measure of red-cell maturity was assessed in 31 patients by flow cytometry using thiazole orange. In group I (n = 39) with immediate graft function, EPO levels increased rapidly from day 2 and remained elevated at the plateau between two and three times the upper limit of normal during the first 2 months. In group II (n = 29) with delayed graft function, EPO levels increased gradually from day 10 when renal function improved significantly. No particular significant biphasic pattern of secretion was detected in group I or II. In both groups, hematocrit rose to over 35% approximately 3 months after RT. In a third group (n = 6) with immediate postoperative acute blood loss and severe anemia, a hematocrit fall was followed by a steep increase in EPO levels with a negative correlation between hematocrit and EPO levels during the first 4 days. During acute rejection, EPO diminished significantly by more than 50% either on the day of diagnosis or on the following days in 8 patients. RMI increased by 25% over the pretransplantation values by 7 days on average before the ARC rose. Thus the RMI seems to be an early sensitive predictor of erythropoiesis after RT. EPO response after RT depends on graft function, and the early transient increase in EPO observed in patients with acute blood loss may explain the apparent biphasic response previously reported.

Adolescent↗
PubMed1995

[Measurement of biological parameters of endothelial origin: value in human pathology].

Endothelial damage is a major factor in the pathogenesis of vascular diseases, but routine investigations of vascular lesions are hampered due to endothelial cell characteristics such as limited accessibility, intrinsic immunological and functional heterogeneity as well as the lack of specific markers. The most frequently used markers are soluble substances, found in plasma, such as the von Willebrand factor, thrombomodulin, tissue plasminogen activator and its inhibitor, or soluble adhesion molecules. Their easy evaluation in semi-routine tests gives access to a global exploration of functional alterations and of abnormal states of endothelial activation. Immunohistological techniques using monoclonal antibodies allow to study the expression of membrane antigens and permit direct and specific investigation of activation states of endothelium. However, the invasive and traumatic characteristics of sampling procedure considerably limit the utilization of immunohistological techniques for clinical applications. Detection in the peripheral blood of endothelial cells detached from vessels could be a good marker for desquamative lesions. From a simple blood sample, it is now possible, using specific immunodetection techniques to isolate circulating endothelial cells present in low numbers in various pathologies associated with vascular injury. Although significant modifications of these markers have been found associated with endothelial alterations, prospective clinical studies are still necessary to demonstrate their clinical relevance in vascular diseases.

Biomarkers↗
PubMed1995

[Detection of circulating endothelial cells: a new diagnostic test of angina at rest].

The diagnosis of spontaneous angina depends on the recording of per-critical electrocardiographic changes. There is no simple biological test to make its retrospective diagnosis. The attack is usually triggered by instability of an atheromatous plaque which fissures and liberates endothelial cells in the blod stream. The detection of these cells cold therefore be a biological sign of this condition. The technique of detection of circulating endothelial cells by immuno-magnetic method was used in 3 groups of patients admitted to hospital within 24 hours: group I comprised 11 patients with acute myocardial infarction, group II comprised 23 patients who had suffered from spontaneous angina with ST segment depression during the attack and significant coronary arterial stenosis, group III comprised 6 patients with chest pain for which coronary angiography is normal and provocative test of spasm is negative. Circulating endothelial cells were detected in all patients of group I (100%), in 18 of the 23 patients of group II (78%) and only in one of group III (18%). These results confer on this biological test for spontaneous angina a specificity and predictive positive value of 83 and 95% and a sensitivity and negative predictive value of 78 and 50%. Therefore the detection of circulating endothelial cells could be used as a simple and reliable test for retrospective diagnosis of spontaneous angina. The mediocre sensitivity and negative predictive value may be explained by a mechanism other than fissuration of atheromatous plaque in some cases of spontaneous angina.

Aged↗
PubMed1994

Plasma thrombomodulin in orthotopic liver transplantation.

Plasma thrombomodulin (TM), a specific marker of vascular endothelial injury was measured pre-, per-, and postoperatively in 16 consecutive patients undergoing orthotopic liver transplantation (OLT). The TM level, which was already elevated preoperatively, remained unchanged during OLT, except for an acute and transitory spike at the time of graft reperfusion. This TM peak is probably attributable to an acute release from the patient's endothelium because the TM level in the last saline rinse of the graft before implantation was low. This TM spike was not correlated with the progressive tissue-type plasminogen activator (t-PA) increase, plasminogen activator inhibitor 1 (PAI-1), or von Willebrand factor (vWF) values. The absence of accumulation of TM in plasma, unlike that of t-PA, suggests that the liver does not play a major role in TM clearance in humans. At the end of surgery, individual TM values returned to preoperative levels and remained unchanged during the 7 days following surgery. This observation suggests that the high (or very high) TM levels measured in these patients might be due to an indirect rather than a direct effect of liver dysfunction on the vascular endothelium which remained damaged during the postoperative period. The possibility that TM might be a predictive marker for thrombotic OLT complications remains to be investigated in a postoperative follow-up study.

Adolescent↗
PubMed1994

[Antiphospholipid antibodies].

The term 'antiphospholipids' (APL) refers to heterogeneous auto-antibodies, including anticardiolipins detected by immunological methods and lupus anticoagulants detected by clotting tests. APL are currently of considerable interest, both from a clinical and a biological point of view, since their presence is associated with thromboembolic events. In this review, the authors emphasize the diversity of the clinical settings where APL are diagnosed and investigate the relationship between APL and thrombosis. The heterogeneity of APL and the lack of standard techniques make their laboratory diagnosis difficult and require the use of various types of tests. Several pathogenic mechanisms, all related to a possible effect of APL on the antithrombotic functions of vascular endothelium, have been proposed: decrease in prostacyclin synthesis, induction of procoagulant activity, inhibition of the endothelial anticoagulant functions, and impairment of fibrinolysis. Given the heterogeneity of these antibodies, it is unlikely that a single mechanism can account for their prothrombotic effect.

Antibodies, Antiphospholipid↗
PubMed1994

Quantitative immune phenotyping: a new dimension for the monitoring of haemopoietic malignancies.

Quantitative data provided by flow cytometers are as yet not fully exploited due to the lack of standardization. However, fluorescence standardization systems are now available which allow the measurement of antigen density on a routine basis and the present review focuses on the interest of such quantitative techniques for the monitoring of haemopoietic malignancies. Antigen quantitation: (i) permits a more objective characterization of positivity, especially in the case of weakly expressed antigens; (ii) facilitates the analysis of complex populations, since certain antigens are expressed at different levels on different cell subsets; (iii) provides new data contributing to a more precise definition of cell differentiation; (iv) is of value to ascertain malignancy from the detection of aberrant antigen densities on putative neoplastic cells; (v) provides additional parameters suitable for the evaluation of residual disease and for the monitoring of immunological therapeutic regimens; (vi) contributes to prognosis. Quantitation of antigen densities should therefore be included in the routine study of haemopoietic malignancies.

Antigens, Neoplasm↗