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Biomedical subjects

J Y Perrot

Publications and source records attributed to J Y Perrot.

At least 37 records · Page 2Linked to original sources
PubMed1993

A possible role for specific "anergy" in immunologic hyporeactivity to donor stimulation in human kidney allograft recipients.

The low immunological reactivity toward donor cells usually observed in transplant recipients has been linked to clonal deletion or suppression of alloreactive cells. However, the anergy of donor-specific reactive cells is another possibility not extensively tested until now in humans. In this case, donor-specific reactive cells would be present and eventually be activated without becoming effector cells (i.e., without secreting IL-2 or becoming cytotoxic) after donor-specific stimulation. We studied 8 patients under low-dose immunosuppressive drugs who displayed hyporeactivity toward donor stimulation. IL-2 production, proliferative response, and cytotoxic activity toward donor cell stimulation was decreased (respectively 22, 53, and 19% of response toward third-party stimulation). In order to evidence anergy, we studied two activation markers (cell size increase and expression of IL-2 receptor [CD25]) in allografted recipient T cells after autologous (background), donor (experimental), and third-party cell stimulation (positive control). We showed that the percentage of CD25+ cells and the cell size increase were similar after donor or third-party cell stimulation and clearly above the background as early as days 1-2 after the beginning of the mixed lymphocyte culture. Moreover, CD4+ and CD8+ cells similarly expressed CD25 after donor or third-party stimulation. Thus, donor-specific reactive cells not only were present but could be activated without becoming effector cells. These data suggest that anergy may be an important phenomenon in allograft tolerance.

Humans↗
PubMed1993

Reversible translocation of glycoprotein Ib in plasmin-treated platelets: consequences for platelet function.

Understanding the effect of fibrinolysis on platelet function is of clinical importance. Plasmin is recognized to affect platelet adhesive function by reducing the interaction of platelet glycoprotein (GP) Ib with von Willebrand factor (vWF) bound to the subendothelium. This platelet function is commonly explored in vitro by the ristocetin-induced agglutination test. Our previous study demonstrated a plasmin-induced redistribution of GP Ib molecules from the platelet surface to the linings of the surface-connected canalicular system (SCCS), a critical mechanism for understanding plasmin-induced GP Ib dysfunction. Here, we demonstrate that neutralization of plasmin by its inhibitors, aprotinin or tripeptide Val-Phe-Lys-CH2Cl, permits a time dependent recovery (within 30 min) of ristocetin-induced agglutination in the platelets which were stimulated by plasmin at < 1 CU ml-1. This functional recovery was accompanied with a restoration of a normal amount of GP Ib on the platelet surface, as measured by the binding of both monoclonal anti-GP Ib antibody SZ 2 and 125I-labelled vWF to the platelets. Cytochalasin D did not inhibit this recovery, suggesting that this process may be due to passive actin depolymerization. These findings were further confirmed by immunoelectron microscopic study. Utilizing the platelets pre-labelled with anti-GP Ib antibody prior to plasmin stimulation, it was demonstrated that the observed recovery is due to a reverse translocation from the SCCS to the plasma membrane of the same GP Ib molecules which were present initially at the cell surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination↗
PubMed1993

Smoking, CD45R0+ (memory), and CD45RA+ (naive) CD4+ T cells.

The relationship between smoking and percentages and counts of T-cell subsets, in particular CD45R0+ (memory) and CD45RA+ (naive) CD4+ lymphocytes, have been assessed in a sample of 311 middle-aged men working in the Paris area. Percentages of lymphocytes with the phenotypes CD4+, CD8+, CD4+CD45R0+, and CD4+CD45RA+ were determined using double immunofluorescence labeling. All cell counts, including CD4+CD45R0+, and CD4+CD45RA+ lymphocytes increased significantly with tobacco consumption, as did the percentages of lymphocytes with the CD4+CD45R0+ and CD4+ phenotypes. The increase in the percentage of lymphocytes with the CD4+CD45RA+ phenotype, although not significant, was similar to that observed in the percentage of CD4+CD45R0+ lymphocytes. When the proportions of CD4+ cells with the CD45R0+ or the CD45RA+ phenotype were considered, no specific modification of any of these two sub-populations was observed: the effect of smoking on memory and naive Cd4+ lymphocytes seemed to be equivalent.

Adult↗
PubMed1991

Temperature dependence of plasmin-induced activation or inhibition of human platelets.

It is known that at 37 degrees C plasmin may have two opposite effects on platelets: at high concentrations (greater than 1.5 caseinolytic units [CU]/mL), plasmin activates platelets; at lower concentrations (0.1 to 1.0 CU/mL) it inhibits platelet activation induced by thrombin, collagen, or calcium ionophore A23187. In this study, we report that when lowering the incubation temperature to 22 degrees C, plasmin at low concentrations (0.1 to 0.5 CU/mL) fully activated platelets. When platelets were treated with 0.2 CU/mL of plasmin, lowering the incubation temperature from 37 degrees C to 22 degrees C resulted in an increase in the expression of fibrinogen receptors, in platelet release and aggregation. Thromboxane A2 was not generated by plasmin treatment at either temperature. Ultrastructural studies showed that platelets responded to low-dose plasmin at 37 degrees C by forming pseudopods, centralizing granules without fibrinogen release, whereas at 22 degrees C the same dose of plasmin caused platelet degranulation with the appearance of alpha-granule fibrinogen within the lumen of the surface connected canalicular system. In addition, at 22 degrees C plasmin at doses insufficient to induce platelet aggregation potentiated platelet response to thrombin. Thus, we suggest that plasmin may initiate both activating and inhibitory processes within platelets and that the change of temperature could influence this balance. These results may be of clinical relevance, because the fibrinolytic system was found activated during cardiopulmonary bypass in which the temperature of patient's blood circulation was reduced. This temperature-dependent behavior is also an interesting model for a further study on platelet response to serine proteinases.

Antibodies, Monoclonal↗
PubMed1991

Role of active center and lysine binding sites of plasmin in plasmin-induced platelet activation and disaggregation.

Previous studies have shown that plasmin can activate platelets and can also disperse platelet aggregates by degradation of fibrinogen bound to platelets. In this study, the role of the active center and the lysine binding sites (LBS) of human plasmin in activating platelets and in dispersing platelet aggregates is investigated using aprotinin and the tripeptide Val-Phe-Lys-CH2Cl to inhibit the active center and using epsilon-aminocaproic acid (EACA) to specifically block the LBS. Our results show that the catalytic activity of plasmin is indispensable both for activating platelets and for dispersing platelet aggregates. Binding of plasmin to platelets through the LBS enhances its activating potential, since both EACA (1 mM) and Lys-plasminogen (molar ratio of plasminogen:plasmin at 2:1 to 4:1) inhibit plasmin-induced platelet activation, whereas Glu-plasminogen at a molar ratio of 15:1 had no effect. Furthermore, plasmin which lacks the LBS (miniplasmin), is about 3 fold less effective in activating platelets. However, plasmin binding through the LBS is not absolutely required to disperse platelet aggregates, since EACA at 30 mmol/l was unable to prevent disaggregation by plasmin (half disaggregation time: 40 min in the presence of EACA against 27 min in its absence). It also appeared that fibrinogen receptors on activated platelets are resistant to plasmin degradation, and that disaggregation of plasmin-induced platelet aggregates was much slower than the degradation of fibrinogen by plasmin.

Amino Acid Sequence↗
PubMed1990

Role of interleukin 2 receptor beta chain in initiating anti-CD3 and interleukin 2-induced proliferation of human resting T cells.

We have examined the role of isolated interleukin 2 receptor (IL2R) beta chains expressed by human resting T cells in the early period of primary T cell activation induced by soluble OKT3 monoclonal antibody (mAb) and exogenous IL2. In the initial 3-day-stimulation phase, high IL2 concentrations were required, in association with soluble OKT3 mAb, to induce the formation of IL2R alpha/beta heterodimers, while later, low IL2 concentrations were sufficient to promote cell growth. When added during the initial phase, TU27 mAb directed at the IL2 binding site of IL2R beta chain substantially inhibited the appearance of functional high-affinity IL2R. Lo-Tact-1 mAb directed at the IL2 binding site of the IL2R alpha chain had only a marginal effect. Strong induction of IL2R alpha mRNA occurred within 3 days upon OKT3 and IL2 stimulation even in the presence of Lo-Tact-1 mAb, but not in the presence of TU27 mAb. OKT3 alone failed to induce significant IL2R alpha gene transcription and that induced by IL2 alone was very weak. The constitutive expression of IL2R beta mRNA was visualized in resting T cells. It remained at a rather stable level, at least during the initial stimulation period which was examined herein. Given the fact that OKT3 alone was ineffective in up-regulating IL2R beta mRNA expression and that pre-incubation of the cells with OKT3 alone did not allow them to respond to high concentrations of IL2, it is highly probable that isolated IL2R beta chains constitutively expressed by CD8+ T cells (the main reactive cells in this system) are primarily responsible for the initial interaction of IL2 with these cells. Such an interaction will result in the formation of high-affinity IL2R and in the initiation of cell proliferation provided that a CD3-derived co-signal is simultaneously delivered to the cells.

Antibodies, Monoclonal↗
PubMed1990

Evolutionary stability of fibrinogen epitopes implicated in fibrin polymerization and in fibrinolysis.

In this work, fibrinogen evolution was analysed by testing the reactivity of fibrinogen from different species with monoclonal antibodies against human fibrinogen fragment D. One epitope concerning the fibrin polymerization site 'a' and two epitopes responsible for tPA binding to fibrin were conserved in all mammalian fibrogens tested but not in crab coagulogen or pleurodella fibrinogen. In these two species, some epitopes which are not implicated in fibrinogen function were conserved. Therefore, we can conclude that polymerizing site 'a' and tPA binding sites have not been modified for at least 80 million years.

Animals↗
PubMed1990

Decreased lymphokine-activated killer cells in kidney transplant recipients. Correlation with a diminished number of CD3-/NKH1+ cells.

The activity of lymphokine-activated killer cells, measured either by a clonal or polyclonal technique, was assessed in 30 kidney transplant recipients (TX), in 13 hemodialyzed patients (HD-CRI), and in 18 normal (N) controls. A highly significant decrease of the LAK activity in TX in comparison with HD-CRI or N (P = 0.0001) was observed. Moreover, the percentage of CD3-/NKH1+ cells was decreased in TX in comparison with N (P = 0.01). LAK activity was strongly correlated (r = 0.72; P = 0.0001) with the percentage of CD3-/NKH1+ cells and not with that of double-positive CD3+/NKH1+ cells. Multivariate analysis showed that the sole independent variable that determined the LAK activity was the percentage of CD3-/NKH1+ cells: the pathological status (TX, HD-CRI, and N) variable was statistically not significant. On the other hand, two T cell-specific functions (IL-2 secretion and specific cytotoxic activity) were, on the whole, preserved in TX. Altogether, these results suggest that TX are LAK deficient predominantly because they have a decreased number of CD3-/NKH1+ cells. The normality of T cell functions suggests that the high rate of malignancies seen in TX is related to this LAK deficiency. Moreover, our study indicates that, in vivo, CD3+ cells do not significantly contribute to the LAK precursors.

Antigens, CD↗
PubMed1988

Parallel induction of fibrinolysis and receptors for plasminogen and urokinase by interferon gamma on U937 cells.

A new cell sorter technique was employed to study the role of interferon gamma (INF gamma) in fibrinolysis induced by U937 monocytic cells. INF-gamma induced the differentiation of U937 cells as evidenced by the appearance of CD 14 antigen on the cell surface. Scatchard analysis and dose response curves showed a parallel increase in the number of receptors on U937 cells capable of accepting exogenous plasminogen and urokinase (UPA) synthetized by differentiating U937 monocytic cells. This would favour an activation of plasminogen by UPA. This adds a new parameter in the regulation of cell-mediated fibrinolysis and may be important in a number of biological processes.

Cell Line↗
PubMed1987

In vitro depletion of clonogenic cells in adult acute lymphoblastic leukemia with a CD10 (anti-cALLA) monoclonal antibody.

A semi-solid medium colony assay was used in common acute lymphoblastic leukemia (cALL) to test growth inhibition of leukemic progenitors (CFU-L) after exposure to monoclonal antibodies (MoAbs) directed against CD10 and CD9 antigens. Peripheral or bone marrow cells from 15 patients were plated after exposure to various concentrations of ALB2, a CD10 cytotoxic MoAb, followed by complement lysis. CFU-L inhibition was complete (no residual colony) in 5 cases (33%), marked (greater than or equal to 95%) in 4 cases (27%), but only moderate (64% +/- 28) in 6 cases (40%). This inhibition was not related to the percentage of cALLA positive cells before exposure to MoAb. In addition, cells of 5 patients were exposed to BA1 (CD24) + complement. In these cases, the proportion of CFU-L inhibition was equal to or higher than with ALB2. In 3 cases, cells were exposed to an association of ALB2 and SB4 (CD19) MoAbs followed by complement lysis, with a marked inhibition (greater than or equal to 99%) in 2/3 cases. These observations give supplementary support to the use of several MoAbs directed against various antigens present at early stages of B differentiation.

Adolescent↗
PubMed1987

Use of bronchoalveolar lavage in the evaluation of methotrexate lung disease.

The results of bronchoalveolar lavage in three patients with a presumptive diagnosis of methotrexate induced lung disease are presented. Lavage fluid was characterised by the presence of large numbers of lymphocytes, which in two patients were predominantly lymphocytes of the T8 phenotype. These findings further support the hypothesis that immune mediated mechanisms may play a part in the pathogenesis of this disorder in some patients, and indicate that bronchoalveolar lavage may be helpful in the evaluation of patients suspected of having methotrexate induced lung disease.

Adult↗
PubMed1987

[A specific marker of thrombolysis: DDE complex].

A specific determination of fibrin degradation product (FbDP) is essential for the monitoring of thrombolytic therapy. In patients under thrombolytic therapy, even with tpA (tissue type plasminogen activator) fibrinogen is degraded, and fragment D derived from fibrinogen degradation, is evidenced in the plasma of treated patients. In order to determine specifically the FbDP, even in the presence of fragment D, we take into account the fact that FbDP are complexes such as DDE complex. Therefore a new Elisa technique is proposed. FbDP and fragment D are captured from plasma by immobilized anti D neo monoclonal antibody which recognizes an epitope accessible on fragment D but does not react with undegraded fibrinogen. DDE complexes are then detected specifically using a peroxidase-labelled anti E antibody. The advantage of this technique is discussed in this paper.

Antibodies, Monoclonal↗
PubMed1987

[Lymphoblastic leukemia and immunological markers].

Acute lymphoblastic leukemia (ALL) is a heterogeneous entity that can be subcategorized on the basis of morphologic aspects, membrane antigens, caryotypic analysis and enzymatic content of the blast cells. Subgroups corresponding to T cells, Band pre-B cells, and non T non B lymphocytes derivations can be defined by immunologic markers. These studies ease the diagnosis and characterisation of ALL, perhaps their treatment, and enhance understanding of the disease.

Antigens, Differentiation↗
PubMed1987

T-cell depletion does not affect long-term human bone marrow culture.

Bone marrow long-term cultures were studied for 8 weeks in four experiments before and after T-cell depletion with a mixture of monoclonal antibodies directed against CD2, CD5 and CD7. No differences in cellularity or granulomonocytic progenitor numbers appeared during the period of culture. We conclude that in vitro treatment in itself is not likely to explain non-take or graft rejection associated with T-depleted bone marrow transplantation.

Animals↗
PubMed1986

A latex immunoassay of fibrin/fibrinogen degradation products in plasma using a monoclonal antibody.

We have developed a latex immunoassay using an anti D neo monoclonal antibody (F2C5) which recognizes an epitope present in fragment D but which is hidden in intact fibrinogen and in early fibrinogen degradation products. This technique was applied directly to plasma of both healthy donors and patients, and was shown to be very convenient for clinical investigation, especially in emergency cases for diagnosis of intravascular coagulation. The use of plasma samples instead of serum offers several advantages: it is not time consuming since blood clotting is not required; it avoids overestimation when fibrinogen cannot be totally clotted, and underestimation due to the binding of nonclottable fibrin degradation products to the clot during clotting in vitro. This monoclonal antibody, which reacts more with FbDP (expressed in fragment D) than with fragment D, does not allow fibrin and fibrinogen degradation products to be differentiated. However, this discrimination does not seem critical for its clinical use since the level of fragment D neo antigen remained within the normal range in 12 cases of spontaneous or venous occlusion-induced hyperfibrinolysis.

Antibodies, Monoclonal↗
PubMed1986

Persistence of bone marrow lymphocytosis after induction treatment in common acute lymphoblastic leukemia. Marker analysis and significance.

In a series of 22 adult acute lymphoblastic leukemias expressing the common acute lymphoblastic leukemia antigen (cALLA +), eight had marrow lymphocytosis greater than 30% (43 +/- 12%) with disappearance of marrow lymphoblasts and correction of bone marrow insufficiency at the end of the induction treatment. Four of these patients were studied for the cALL antigen at this time and had persistence of this immunological marker (62 +/- 15% of the mononuclear bone marrow cells). The evolution of these patients suggests that these patients were not in complete remission and emphasizes the usefulness of cALLA determination in cases with borderline excess of marrow lymphocytes.

Acute Disease↗