Search PubMed⌕ Search

Biomedical subjects

P Debre

Publications and source records attributed to P Debre.

At least 37 records · Page 2Linked to original sources
PubMed1994

Alveolar CD8+CD57+ lymphocytes in human immunodeficiency virus infection produce an inhibitor of cytotoxic functions.

We investigated the CD8+CD57+ alveolar cell functions and their immunoregulatory role in lungs from HIV-seropositive patients with the clinical presentation of lymphocytic alveolitis at different stages of human immunodeficiency virus (HIV) disease. We previously reported, at Stage IV of HIV infection, an expansion of CD8+CD57+ alveolar lymphocytes mirroring the decline of local anti-HIV cytotoxic T-lymphocyte (CTL) responses, and demonstrated that sorted CD8+CD57+ alveolar lymphocytes inhibited the effector phase of these HIV-specific CTL. In the present study, we show that the expansion of CD8+CD57+ alveolar T cells can also be detected at stages II and III of HIV disease, although at a lower degree than observed at Stage IV of HIV infection. When sorted, these CD8+CD57+ alveolar lymphocytes block effector killer cells such as allospecific CTL, natural killer (NK), and lymphokine-activated killer (LAK) cells. The mechanism of action of these inhibitory T-lymphocytes has been further studied and we demonstrated that: (1) cell-to-cell contact between inhibitor and killer is not required, (2) nonstimulated alveolar CD8+CD57+lymphocytes but not CD57- lymphocytes spontaneously release a solube inhibitor of cytolytic functions (ICF). This inhibitory activity of alveolar CD8+CD57+ cells is mediated by a glycosylated protein which is distinct from tumor necrosis factor-alpha (TNF alpha), TNF beta, transforming growth factor-beta 1 (TGF beta 1), TGF beta 2, interferon alpha (IFN alpha), interferon gamma (IFN gamma), and prostaglandins. The release of such an inhibitor of killer cell functions by CD8+CD57+ lymphocytes in the lungs, which are an important interface between the sterile body and the antigen-laden environment, may play a role in the local control of cell immunity.

AIDS-Related Opportunistic Infections↗
PubMed1994

T lymphocyte subsets in primary antiphospholipid syndrome.

OBJECTIVE: To study T, natural killer (NK) and B blood cell subsets in primary antiphospholipid syndrome (APS). METHODS: We studied 10 patients with primary APS and 12 healthy subjects. Blood lymphocytes counts, proportions of B cells (CD19+), total CD5 and CD5 B cells, NK cells (CD16+CD56+), T cells (CD3+), CD4+ helper (naive CD4+CD45RA+, memory CD4+CD45RO+ and CD4+CD29+, activated CD4+CD25+), CD8 (immunoregulatory CD8+CD57+, activated CD8+HLA-DR+) T cell subsets were measured by flow cytometry analysis. RESULTS: In the primary APS group, we observed a lower total lymphocyte count (p = 0.009), an expansion of naive CD4 cells (p = 0.025), a lower proportion of memory CD4 cells (p = 0.04) and an increased ratio of naive/memory CD4 cells (p = 0.015). CONCLUSION: Blood T cells phenotypes in primary APS differ markedly from healthy controls, indicating that immunologic abnormalities in primary APS might extend beyond autoantibody production.

Adult↗
PubMed1993

CD34-expressing human thymocyte precursors proliferate in response to interleukin-7 but have lost myeloid differentiation potential.

CD34 is a marker for pluripotent stem cells also present on lineage-committed hematopoietic progenitors from bone marrow and a subpopulation of immature thymocytes. To characterize these early immature thymocytes, we have studied 24 pediatric thymus samples for CD34/7 expression. Three subpopulations could be defined from these T-cell receptor (TcR-) immature thymocytes: CD34+7++ (12.0 +/- 5.8), CD34-7++ (12.6 +/- 8.6), and CD34-7+ (71.5 +/- 17.0%). CD7++ represents upregulation of this antigen and is expressed by cells of a blast-like morphology. Three-color flow cytometric analysis of these three subsets suggests the following ordered differentiation sequence: CD34+7++1-4-8-45RA+-->CD34+7++1+ 4+8-45RA+/- -->CD34-7++1+4+8-+45RO+-->CD34-7+1++4+8+45RO+. Early immature thymocyte cell division is essential in the thymus to generate a large number of precursors before the initiation of the selection process. We observed that both CD2 as well CD28 activation pathways were inefficient to serve as costimulant with phorbol ester 12-O-tetradecanoyl phorbol 13-acetate or interleukin-2 (IL-2) to induce the proliferation of the three CD34/7 subsets isolated by cell sorting. However, whereas IL-1, IL-2, IL-3, IL-4, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor were ineffective, IL-7 was a potent cytokine, alone or in synergy with stem cell factor (SCF) to induce immature thymocyte proliferation. The proliferation induced by IL-7 or IL-7 + SCF is restricted to the CD34+ cells and, after 4 or 8 days of culture with IL-7, some CD34+7++ acquire the expression of CD4 and/or CD8, but remain CD3/TcR-. We also tested the myeloid differentiation capacity of these CD34 immature thymocytes. Using two different approaches, myeloid colony formation in methylcellulose and limiting dilution analysis in the presence of myeloid growth factors, we were unable to detect myeloid differentiation capacity from CD34+ early thymocytes, whereas CD34+7+ from bone marrow contained about 10% of the clonogenic cells present in the CD34+7- fraction. Together, these data support the concept that thymic CD34+7++ represents the earliest thymic subset of fully committed T-lineage cells, capable of proliferating specifically to IL-7.

Antibodies, Monoclonal↗
PubMed1993

IL-4 release by human leukemic and activated normal basophils.

Recently, authors have addressed the ability of human basophils to produce IL-4. We report here the detection of significant serum IL-4 levels in a case of acute transformation of chronic myelogenous leukemia with a predominant basophilic cell population. Leukemic basophils were isolated from patients' PBMC and assayed for their IL-4-mRNA expression and their ability to secrete this cytokine in vitro. Leukemic basophilic cells (> 90% toluidine blue positive) but not other PBMC expressed IL-4-mRNA, contained IL-4 protein, and secreted this cytokine. These cells had a spontaneous IL-4 secretion ability, without a need for an exogenous activator. Meanwhile, IL-4 release was significantly increased following leukemic cell activation through Fc epsilon RI-ligation or by Ca2+ ionophore. IL-4 and its mRNA were also detected in leukemic basophils from three other chronic myelogenous leukemia patients with moderate basophilia (13, 14, and 23% basophils in PBMC). To confirm these data in normal human cells, we have developed a method to obtain large numbers of purified basophils from human bone marrow cell cultures. In contrast to leukemic basophils, normal cells required in vitro activation through Fc epsilon RI ligation or by Ca2+ ionophore to express and secrete IL-4. Leukemic and normal basophils secreted histamine following in vitro activation, but were negative for tryptase. These data thus demonstrate the in vivo and in vitro ability of human basophils to produce IL-4.

Basophils↗
PubMed1993

Interleukin 4 inhibits the proliferation and promotes the maturation of human leukemic early B cells.

The effects of interleukin 4 (IL-4) on human leukemic precursor B-cell lines were investigated. Recombinant IL-4 (rIL-4) was added to three acute lymphoblastic leukemia-derived pre B-cell lines: Reh, Km3 and Nalm-6. Our results show that rIL-4 significantly decreases continuous proliferation of Reh and Km3 cells while Nalm-6 cells have a limited response in this respect. This rIL-4 effect is dose-dependent and can be neutralized by anti-IL-4 monoclonal antibody (mAb). Furthermore, rIL-4 down-regulated IL-3-induced proliferation of Reh cells. Phenotypic analysis of rIL-4-treated cells points to significant induction of surface marker maturation of leukemic cells by this cytokine. Together, these in vitro data suggest that IL-4: 1) inhibits the proliferation and 2) promotes the differentiation of certain human leukemic B-cell precursors.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1992

Consistency of routine measurements of CD4+, CD8+ peripheral blood lymphocytes.

In order to evaluate the reliability of CD4 and CD8 T lymphocyte counts in large scale studies, a quality control study was performed in 12 French laboratories. CD4 and CD8 counts, assessed by various haematological and immunological techniques, were compared in order to assess possible differences between the laboratories and the techniques used. Our data showed that (a) the consistency of CD4 measurements was satisfactory since the between-laboratory coefficient of variation for absolute CD4 cell numbers above 200/mm3 was around 15% instead of 5-10% for all laboratories but one; (b) the major sources of variability arose from the use of automatic devices in the two-step measurement procedure: immunophenotyping and haematological counting. These data suggest that multicentre assays of CD4 and CD8 counts result in some increase in their variability. Nevertheless the results of large multicentric trials can be extrapolated with confidence in the routine care of HIV+ patients. Together, the results justified the involvement of several experienced laboratories in a clinical trial of HIV-related disease.

CD4 Antigens↗
PubMed1992

CD2 triggering stimulates the formation of platelet-activating factor-acether from alkyl-arachidonoyl-glycerophosphocholine in a human CD4+ T lymphocyte clone.

A human CD4+ T lymphocyte clone synthesized platelet-activating factor (PAF) acether when stimulated via the CD2 pathway. PAF-acether was characterized by biochemical and biophysical properties and precursor-product relationships (alkyl-acyl-sn-glycero-3-phosphocholine (GPC)----alkyl-lyso-GPC (lyso-PAF)----PAF-acether) were demonstrated. The clone contained substantial amounts of alkyl-acyl-GPC. i) Hydrolysis of alkyl-acyl-GPC upon CD2 stimulation was evidenced: [3H]alkyl-lyso-GPC was formed from [3H]alkyl-acyl-GPC in [3H] alkyl-labeled cells; alkyl-lyso-GPC production was also bioassayed after CD2 triggering. ii) The rate of arachidonate transfer from diacyl-GPC to alkyl-acyl-GPC increased after CD2 stimulation of the [3H]arachidonate-labeled P28D T cells, demonstrating alkyl-lyso-GPC formation. iii) Comparison of the molecular species of the produced PAF-acether with those of arachidonate-containing alkyl-acyl-GPC raises the possibility that the produced PAF-acether is related to alkyl-arachidonoyl-GPC.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1992

Internalization of HIV glycoprotein gp120 is associated with down-modulation of membrane CD4 and p56lck together with impairment of T cell activation.

We previously demonstrated that long term treatment of the Ag-specific CD4+ T cell clone P28D with soluble HIV envelope glycoprotein gp120 results in a marked impairment of CD3/TCR-mediated responses. In this report, to further understand these inhibitory effects, the binding properties and internalization of gp120 have been investigated, in parallel with functional studies, in long term incubations of P28D cells with gp120. Immunofluorescence studies show that surface-bound gp120 level is maximal within 1 h of incubation at 37 degrees C and then gradually decreases. This decrease is accompanied by a progressive down-modulation of membrane CD4 (30-35% loss over a 18-h incubation period) without concomitant alteration of the CD4 mRNA steady-state level. Similar experiments performed with 125I-labeled gp120 demonstrate that the glycoprotein is progressively internalized (up to 35% internalized material after 18 h) and that it accumulates inside the cells. Confocal microscopy studies show that internalized gp120 is concentrated in localized intracellular compartments. CD4 also accumulates in compartments with a similar localization and is stained with mAb OKT4 but not with mAb OKT4a. Concomitantly to internalization of gp120 and disappearance of membrane CD4, a correlated loss of the CD4-associated tyrosine kinase p56lck is evidenced. Interestingly, a progressive impairment of the P28D responses to specific Ag or to anti-CD3 mAb is also observed. Inhibitions of T cell proliferation increase with the degree of both CD4 and p56lck down-modulation. Removal of exogenous gp120 results in a rapid and spontaneous release of internalized gp120 into a degraded form. A progressive restoration of CD4 and p56lck levels is also noticed. In parallel, CD3/TCR-mediated responses of clone P28D are fully recovered. Altogether, our results suggest that HIV-1 glycoprotein gp120 is able to down-modulate membrane CD4 presumably by a cointernalization process and to further down-modulate the associated p56lck. This dual phenomenon is presumably involved in the direct immunosuppressive effect of gp120 on the CD3/TCR-mediated activation pathway.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1992

CD4+CD7-CD57+ T cells: a new T-lymphocyte subset expanded during human immunodeficiency virus infection.

CD7 and CD57 are two cell surface molecules related to the differentiation or functional stages of CD4+ T cells. The CD4+CD7- T cells represent a minor subset of CD4+ cells in normal individuals and are considered to contain the normal counterpart of Sézary T cells; the CD4+CD57+ peripheral blood lymphocytes (PBL) are detectable in long-term renal allograft recipients. We compared the cell surface expression of these CD7 and CD57 markers on CD4+ T lymphocytes in peripheral blood and lymphoid organs from normal individuals and human immunodeficiency virus (HIV)-infected patients. Our results indicate that CD4+CD7- T cells in normal PBL do not express CD57 and were poorly responsive to anti-CD3 monoclonal antibody (MoAb), the activation being restored by addition of anti-CD28 MoAb. This CD4+CD7- cell subset is increased in peripheral blood during HIV infection, and its progressive expansion mirrors both the absolute and relative decrease of CD4+ T cells. The lack of CD7 expression is correlated with CD57 acquisition on CD4+ T cells because CD4+CD7-CD57+ cells represent a major component of the CD4+CD7- subset in HIV-infected patients. Our results suggest that the presence and the expansion of CD4+CD7-CD57+ T lymphocytes, which do not behave as previously defined helper subsets, may participate to the immune dysfunction observed during HIV infection.

Antigens, CD↗
PubMed1992

Human trophoblast cells express CD4 and are permissive for productive infection with HIV-1.

The European collaborative study of HIV-infected pregnant women in Europe now indicates a 13% risk of fetal HIV infection (originally thought to be about 30%, and possibly higher in some countries). Several reports suggest trans-placental passage. However, the detailed mechanisms associated with such vertical transmission have not yet been clarified. We have examined the possibility that HIV enters placental tissue from maternal blood via binding to CD4 and Fc receptors (FcR) at the trophoblast level, allowing intraplacental infection. Here we report the detection of several FcR with distinct localization in the placental villus as well as CD4 surface expression on human trophoblast cells. In addition, we show that trophoblastic cells interact specifically with the gp120/gp160 viral envelope protein. By their tissue localization, these receptors could be responsible for the entry of HIV into the fetal placental cells. Furthermore, purified placental cells can be directly infected by HIV in vitro, and the infection is inhibited by soluble CD4. This suggests a crucial role of the CD4 receptor but an additional way of entry cannot be excluded. Such an in vitro model may be suitable for further studies concerning placental HIV transmission and its prevention.

CD4 Antigens↗
PubMed1992

Carboxyl-terminal and central regions of human immunodeficiency virus-1 NEF recognized by cytotoxic T lymphocytes from lymphoid organs. An in vitro limiting dilution analysis.

Cytotoxic T lymphocytes (CTL) specific for human immunodeficiency virus (HIV) proteins have been analyzed in lymphoid organs from seropositive patients. Indeed, an active HIV replication coexists with a major CD8+ lymphocytic infiltration in these organs. We have shown in a previous report that HIV-seropositive patients lungs were infiltrated by HIV specific CD8+ lymphocytes. In the present report, we show that HIV-specific CTL responses can also be detected in lymph nodes and spleens, and were mainly directed against the ENV, GAG, and NEF HIV-1 proteins. The primary NEF-specific CTL responses were further characterized by epitope mapping. Determination of epitope-specific CTL frequencies were performed by limiting dilution analysis. Our results indicated that, in addition to the central region of NEF (AA66-148), a new immunodominant region is recognized by CTL. This region corresponds to the carboxyl-terminal domain of NEF (amino acids 182-206). AA182-206 is recognized in association with at least two common human histocompatibility leukocyte antigen (HLA) molecules (HLA-A1 and B8), with clonal frequencies of one CTL per 10(-5) to 10(-6) splenic lymphocytes. Our data indicate that lymphoid organs may represent a major reservoir for in vivo activated HIV-specific CTL. Furthermore, the carboxyl-terminal domain of NEF was found to be conserved among several HIV strains. Therefore, our finding is of interest for further HIV vaccines development.

Amino Acid Sequence↗
PubMed1992

[Lymphocytic alveolitis in the early stages of HIV infection: correlation with biological and prognostic factors].

Broncho-alveolar lavage was performed to assess the degree of pulmonary lymphocytic alveolitis in 32 asymptomatic patients who were infected with the Human Immunodeficiency Virus (VIH). The patients were stages II and III of the CDC classification and the aim of the study was to determine the frequency, nature and prognostic role of the findings. 62.5% of the subjects (20/32) presented with a lymphocytic alveolitis which consisted predominantly of CD8 lymphocyte (64.3 +/- 3.5%), in the absence of an opportunistic infection or broncho-pulmonary tumours. Two sub-populations of alveolar CD8 were shown at comparable levels, a) sub-population CD8+D44+ (22.1 +/- 5%), in whom we showed the possession of cytotoxic activity in particular specific for VIH; b) sub-population CD8+CD57+ (19.6 +/- 3%) which we have shown to be capable in vitro of inhibiting the effector phase of cytotoxic activity of CD8+D44+ alveolar cells specific for VIH. In this group of 32 patients the occurrence of an alveolitis was not correlated with the usual prognostic factors of infection by VIH measured simultaneously with broncho-alveolar lavage (the level of CD4+ blood lymphocytes, and the beta 2-plasma microglobulins and the presence of p24 antigenaemia). In addition the level of CD4 lymphocytes supperior to 400/mm3 and of beta 2-microglobulins less then 3 mg/l whether a lymphocytic alveolitis was there or not confirmed the relatively poorly developed state of the VIH infection in these asymptomatic patients. Also the occurrence of a lymphocytic alveolitis did not seem to be linked to progression of the disease in the group of patients studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of CD23 on purified human hematopoietic cells.

We report herein the effect of soluble CD23 (sCD23) on the differentiation of lymphoid and myeloid precursors. CD23 is known as the low affinity receptor for IgE. In addition to it, our results indicate that sCD23 in synergy with IL1 is able to promote the maturation of normal and leukemic hematopoietic progenitor cells.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1991

Stathmin phosphorylation patterns discriminate between distinct transduction pathways of human T lymphocyte activation through CD2 triggering.

CD2 triggering of human T lymphocyte activation has been associated with the activation of different interacting protein kinases, including protein kinase C (PKC). However the precise roles of its phosphorylated substrates are still unknown. We show here that PKC-dependent and -independent pathways are responsible for the CD2-induced phosphorylation of stathmin, a ubiquitous soluble phosphoprotein, most likely acting as a general intracellular relay integrating various second messenger pathways. The phosphorylated variants of stathmin provide a fingerprint reflecting the second messenger pathway(s) stimulated. The respective roles of both PKC and stathmin in the regulation of T lymphocyte proliferation are discussed.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

Cyclic AMP- and inositol phosphate-independent inhibition of Ca2+ influx by cholera toxin in CD3-stimulated Jurkat T cells. A study with a cholera toxin-resistant cell variant and the Ca2+ endoplasmic reticulum-ATPase inhibitor thapsigargin.

In this report, we describe a Jurkat cell variant, termed JCT8, the selection of which is based upon its resistance to cell-growth inhibition mediated by the holotoxin of Vibrio cholerae, cholera toxin (CT). JCT8 cells exhibit normal cAMP production in response to various cAMP inducers, including CT, together with conserved ADP ribosylation in vitro of G-protein Gs alpha by the A subunit of the toxin. However, after a 4-h pretreatment with CT, JCT8 cells have a conserved expression of cell-surface CD3 molecules. These effects are in contrast to those elicited by the toxin in long term PGE2-desensitized Jurkat cells, which remain as sensitive as the wild type to the inhibitory action of CT on cell growth and CD3 cell-surface expression, despite poor responsiveness to CT with regard to cAMP production. In JCT8 cells, Ca2+ mobilization induced via the CD3/TCR is maintained after CT treatment contrasting with its complete suppression in the wild-type and in the PGE2-desensitized cells. However, as in the other cell types, CT still suppresses Ca2+ influx in JCT8 cells. Increase in inositol phosphates by CD3 stimulation of JCT8 cells, including of inositol 1,4,5-triphosphate (I(1,4,5)P3), is only partially antagonized by CT. This suggests either that in JCT8 cells there is a different susceptibility of Ca2+ mobilization and influx to partial inhibition by CT of CD3-triggered phospholipase C (PLC)-induced phosphoinositide hydrolysis or that an additional and PLC-independent suppressive effect of the toxin on Ca2+ influx may exist. To investigate this particular point further, we use Thapsigargin, a Ca(2+)-endoplasmic reticulum ATPase inhibitor that can mobilize in human T lymphocytes I(1,4,5)P3-dependent intracellular Ca2+ pools by a PLC-independent pathway. We demonstrate that the Ca2+ influx triggered in the wild-type Jurkat cells or in JCT8 cells by Thapsigargin is antagonized by CT. The present data are therefore consistent with the idea that CT specifically impairs in the Jurkat T cell model the entry of Ca2+ from extracellular spaces by a mechanism independent not only from cAMP but also in part from inhibition by the toxin of phosphoinositide hydrolysis.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

A soluble factor released by CD8+CD57+ lymphocytes from bone marrow transplanted patients inhibits cell-mediated cytolysis.

We report a new inhibitory activity of CD8+CD57+ peripheral blood lymphocytes from allo-bone marrow transplant patients. Positively selected CD8+CD57+ lymphocytes act as potent inhibitors of allospecific cytolytic T lymphocyte and lymphokine activated killer cell cytolytic activities. These suppressor cells are mature T cells expressing the CD2, 5, 7, CD3-TcR alpha beta complex, and lack natural killer cell markers as well as cytolytic function. Their inhibitory activity on both cytolytic processes and T-cell proliferation is mediated by a non-antigen-specific soluble factor released by CD8+CD57+ cells in culture supernatants. Preliminary characterization suggests that the CD8+CD57+ cells' inhibitory activity is mediated by a low molecular weight, glycosylated factor as indicated by its less than 1S coefficient of sedimentation and its binding to concanavalin A lectin.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

MS-8209, a new Amphotericin B derivative that inhibits HIV-1 replication in vitro and restores T-cell activation via the CD3/TcR in HIV-infected CD4+ cells.

A new Amphotericin B derivative, MS-8209, which retains high antifungal activity with greatly reduced toxicity and improved solubility, has been developed. We investigated the antiviral properties of MS-8209 in Jurkat and CEM T-cell lines and in peripheral blood mononuclear cells infected in vitro with HIV-1BRU. Our results demonstrate, by determination of reverse transcriptase activity and p24 antigen level titration in cell culture supernatants, that MS-8209 inhibits HIV-1 replication in all cell types at concentrations without cytotoxicity. MS-8209 also prevents membrane expression of the HIV-1 large envelope glycoprotein gp120 and the decrease in CD4 level at the surface of infected cells. HIV-1-infected Jurkat cells exhibit a severe signalling defect at CD3 stimulation. Treatment with MS-8209 restores normal responsiveness at CD3 as assessed by measurement of inositol triphosphate accumulation and calcium flux. Finally, our results indicate that MS-8209 inhibits HIV-1BRU replication without preventing virus binding and penetration into target cells.

Amphotericin B↗