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Biomedical subjects

R Depieds

Publications and source records attributed to R Depieds.

At least 19 recordsLinked to original sources
PubMed1986

Detection of HTLV-I (human T-cell lymphotropic virus, type I) proviral DNA in leukemic cells from a French patient with Sezary syndrome.

Human T-lymphotropic type I (HTLV-I) proviral sequences were detected in leukemic cells of a patient living in Marseilles (south of France) and suffering from Sezary syndrome. He did not have any travel history outside France and did not receive blood transfusion or hepatitis B vaccination. This case of HTLV-I positive Sezary syndrome is the first one described outside the known endemic regions for HTLV-I. Moreover, this patient was found to be negative for viral antibodies. This observation should therefore stimulate new and thorough analysis of the association of this human retrovirus with leukemia and lymphoma in the Mediterranean region, both by seroepidemiological and molecular biology techniques.

Aged↗
PubMed1985

Immunoregulatory activities of human trophoblasts mediated by polyamine complexes.

In a previous publication we described the presence in human placenta (HP) of immunosuppressive factors inhibiting the lymphoproliferative responses to mitogen. The results of further study reported herein indicate that the substance involved is of a syncytiotrophoblastic origin, that it is thermostable to 100 degrees C for 1 hr, and of low molecular weight, i.e. 3,500. It was defined as a polyamine conjugate with nucleic acids. Trophoblast cell extracts lost their immunosuppressive ability after heating in cultures of human lymphocytes supplemented with 5% autologous serum. These effects were, however, preserved both in cultures assayed in 5% fetal calf serum and in those to which purified polyamine oxidase (PAO) was added to autologous serum. Trophoblast cell extract was found to contain polyamine oxidases. Placental PAO can be inhibited by quinacrine a typical inhibitor of flavoprotein enzymes but not by isoniazid, an inhibitor of pyridoxal enzymes; this would suggest that the enzymes in human placenta are of a tissular rather than seric origin. The implication of these observations is that immunosuppression is mediated by oxidative products issued from an interaction between polyamine and polyamine oxidase in the syncytiotrophoblast cytosol. This interaction may constitute the basis for a local immunological barrier and may be involved in the protection of the fetus against maternal immune rejection.

Animals↗
PubMed1984

Effect of age on different receptors and functions of phagocytic cells.

Different tests were performed on 15 young (age between 17 and 39) and 13 older (62-83) subjects. Blood polymorphs and monocytes were separately tested for ingestion of 3 different particle species and stimulation of superoxide anion production. The erythrocyte sedimentation rate and the serum concentrations of 10 proteins possibly related to inflammatory processes were also determined. It is concluded that: Individual variations of phagocyte ability to be stimulated by different cell types are independent processes. Aged people displayed selective decrease of Fc receptor-mediated phagocytosis by granulocytes and possibly selective impairment of nonspecific phagocytosis by monocytes. Further, the IgM level was decreased whereas the IgA, C-reactive protein and erythrocyte sedimentation rate were higher in old people than in young subjects. Correlations were found between the serum concentrations of some protein species and phagocytic function, but further experiments were coincidental (if both parameters were age-related) or revealed some causal link. It is suggested that our procedure provides a simple and reproducible way of testing many independent functions of phagocytic cells.

Adolescent↗
PubMed1983

An OKT4+ T-cell population with suppressor activity in Sézary syndrome.

This report describes a case of Sézary syndrome with the surface marker phenotype of a mature distinct T-cell subset OKT3+, OKT4+, OKT8-, OKT17+, OKIal-(+). Functional studies indicated that the patient's peripheral blood cells showed a very low proliferative response to non-specific mitogens (phytohaemagglutinin, concanavalin A, pokeweed mitogen) and failed to differentiate into plasma cells in a pokeweed mitogen--immunoglobulin-synthesis-driven system. In coculture with normal cells the leukaemic cells were able to suppress lectin-induced T-cell proliferation and B-cell differentiation in a dose-dependent manner. Suppressor function was not radiosensitive and did not require the presence of the OKT8+ subset for expression. These Sézary cells thus represent a suppressive T-cell subset within the OKT4+ population. This subset may well correspond to the recently described OKT4+, OKT17+ normal suppressor cells. These findings would therefore illustrate a pathological and possibly clonal expansion of a normal OKT4+ suppressor T-cell subset.

Adult↗
PubMed1983

Dissociation between phagocytosis and phagosome-lysosome fusion.

The acridine orange technique was used to explore phagosome-lysosome fusion (P-L fusion) in thioglycollate-elicited rat peritoneal macrophages. Sheep red blood cells were coated with IgG or IgM plus complement, or treated with neuraminidase, tannic acid or glutaraldehyde; then both their capacity to be ingested by macrophages and their ability to induce P-L fusion after ingestion were assayed. Their capacity to be engulfed by macrophages was similar, but glutaraldehyde-treated erythrocytes were far more efficient than the other particles in triggering P-L fusion. Hence, both processes must be driven by different mechanisms. No correlation was found between the surface charge of test particles (as assayed by cell electrophoresis) and their ability to trigger phagocytosis or P-L fusion. However, glutaraldehyde-treated erythrocytes were found to be more hydrophobic than the other particles, as previously reported. Hence, particle hydrophobicity might favor P-L fusion. The implication of these findings are discussed.

Animals↗
PubMed1982

Nonspecific binding by macrophages: different modulation of adhesive properties of rat peritoneal cells after plating on a glass or a plastic surface.

Rat peritoneal cells can bind immunoglobulin-coated sheep red cells (IGSRC), glutaraldehyde-treated sheep red cells (GSPC), Leishmania, latex beads, and autologous thymocytes in a serum-deprived medium. When macrophages were plated on plastic Petri dishes, their ability to bind thymocytes and GSRC was decreased ninefold and fourfold, respectively, as compared to macrophages adhering to glass coverslips. However, the binding of IGSRC, Leishmania, and latex was not significantly dependent on the nature of the surface where peritoneal cells were plated. Sequential adhesion to plastic and glass did not reveal any cell subpopulation adhering only to one substrate. The ability of plastic-bound macrophages to bind thymocytes or GSRC was not restored after a 16 hr culture. Hence, some cell properties may be strikingly dependent on the nature of the surface where these cells are plated.

Animals↗
PubMed1981

Non-specific binding by macrophages: evaluation of the influence of medium-range electrostatic repulsion and short-range hydrophobic interaction.

Rat peritoneal macrophages can bind glutaraldehyde-treated human rat cells (GHRC), but not normal human red cells (HRC). When the surface charge of HRC was reduced by treating them with neuraminidase (to remove some negative sialic acid residues) or coating them with polylysine (a positively charged polymer), no substantial binding to macrophages was obtained. However, a similar reduction of the surface charge of GHRC resulted in sevenfold enhancement of their binding of macrophages. All erythrocyte batches were tested with a phase partition technique: only glutaraldehyde-treated cells were found hydrophobic. It is concluded that: i) Short range hydrophobic interactions are responsible for macrophage-GSRC adhesion. ii) Medium range electrostatic repulsion may substantially hamper any close approach of the macrophage and particle surface in physiological conditions.

Animals↗
PubMed1980

Non-specific binding by macrophages: existence of different adhesive mechanisms and modulation by metabolic inhibitors.

Rat peritoneal cells were made to bind test particles of five different species: immunoglobulin-coated sheep red cells (IGSRC), glutaraldehyde-treated sheep red cells (GSRC), leishmania, latex beads and tumour cells. The dependence of binding on various physicochemical parameters was studied: the binding of latex or leishmania resisted cold (4 degrees), azide, cytochalasin B, ethyleneglycol and dimethylsulphoxide (DMSO). The binding of IGSRC resisted cold and azide, but it was inhibited by cytochalasin B, ethyleneglycol and DMSO. The binding of GSRC was inhibited by cold, azide and ethyleneglycol, but not by cytochalasin B and DMSO. The binding of tumour cells was inhibited by azide, cytochalasin B, ethyleneglycol and DMSO. An attempt was made to saturate selectively some adhesive sites of macrophage membranes: glutaraldehyde-treated bovine albumin (GBSA) inhibited the ingestion of latex and GSRC, not leishmania and IGSRC, whereas a crude leishmania extract (CLE) inhibited the ingestion of all tested particles except latex. Antigen-antibody complexes inhibited the ingestion of IGSRC and leishmania, not latex and GSRC. Rat macrophages were made to bind radio-iodinated GBSA (GIBSA). The uptake of glutaraldehyde-treated albumin was proportional to the amount of substrate the cells were incubated with over a wide concentration range. This uptake was not a result of endocytosis, and it was far more efficient than that of peroxidase. Macrophage-particle interaction was studied with electron microscopy. The binding of IGSRC and leishmania to macrophages involved large areas where the interacting membranes were separated by a low density gap of constant width. The interaction of GSRC and latex with macrophages was much more patchy and irregular. Further, no redistribution of the macrophage surface polysaccharides seemed associated with the binding of GSRC. It was concluded that several different mechanisms and different membrane adhesive structures are involved in non-specific recognition by macrophages. Further, non-specific binding sometimes requires an active cell participation. Several testable hypotheses are described, which suggest further experiments in order to obtain a fuller insight into the mechanism of rosette formation.

Animals↗
PubMed1979

[Existence of several non-specific recognition systems in macrophages].

Rat peritoneal cells were made to bind five particle species: immunoglobulin-coated Sheep red cells, glutaraldehyde-treated Sheep red cells, latex beads, leishmania and tumor cells. The dependence of binding on various physico-chemical parameters was studied. The binding of latex beads or Leishmania was not inhibited by cold (4 degrees C), sodium azide, cytochalasin B and ethyleneglycol or dimethylsulphoxide. The binding of immunoglobulin-coated Sheep red cells was unaffected by cold and azide, but it was inhibited by cytochalasin B, ethyleneglycol and dimethylsulphoxide. The binding of glutaraldehyde-treated Sheep red cells was inhibited by cold, azide and ethyleneglycol, but it resisted cytochalasin B and dimethylsulphoxide. The binding of tumor cells was inhibited by azide, cytochalasin B, ethyleneglycol and dimethylsulphoxide. It is concluded that: (a) macrophages are endowed several sets of non-specific binding structures that are differently affected by physico-chemical parameters, which provides a simple way of characterizing them; (b) the expression of a given binding structure on the macrophage membrane is modulated by metabolic inhibitors; (c) some lymphocytes were able to bind tumor cells or Leishmania. Thus, lymphocytes and macrophages might share some non-specific adhesive structures.

Agglutination Tests↗
PubMed1979

Evaluation of intercellular adhesion with a very simple technique.

Rosetting techniques are widely used to quantify or purify various lymphocytic subpopulations; however, these techniques cannot discriminate between different receptors of similar specificities and different binding strengths, further, they do not provide any information concerning the molecular mechanisms involved in cell-cell adhesion. This paper describes a very simple technique of assaying rosette stability: cell suspensions are driven with known pressure through a calibrated needle with a syringe. Adhesion is quantified before and after this treatment. This procedure did not damage rat peritoneal cells used in a model system. Further, this method yielded fairly reproducible results and allowed a crude estimate of the force involved in the binding of glutaraldehyde-treated sheep red cells (GSRC) or immunoglobulin-coated sheep red cells (IGSRC) by rat macrophages (an average force of 0.8 x 10(-7) Newton was needed to separate 50% of bound IGSRC from macrophages). Binding and binding strength were found to be independent parameters. Last, this method possibly provided a way of separating two distinct subpopulations of rat macrophages. It is suggested that this technique might be routinely used to refine rosette studies.

Animals↗
PubMed1979

[Macrophage receptors].

Macrophages are involved in many immunological functions such as phagocytosis, cytotoxicity, antigen binding and cooperation with lymphocytes. The triggering of those functions involves membrane receptors. Several receptors species are well characterized, but some phenomena can be accounted for only if macrophages are endowed with nonspecific adhesive structures. A study of the effect of various physical or chemical factors on the binding of several particle species by rat peritoneal macrophages allowed us to classify nonspecific receptors and discuss the mechanisms involved in some types of cellular interaction.

Animals↗
PubMed1979

Non-specific recognition in phagocytosis: ingestion of aldehyde-treated erythrocytes by rat peritoneal macrophages.

Particles were chemically modified with aldehydes and incubated with rat peritoneal cells for phagocytosis. All dialdehydes and lower monaldehydes tested (methanal, ethanal and propanal) made sheep erythrocytes phagocytosable. Failure of higher monaldehydes to induce phagocytosis of treated erythrocytes was not due to lack of reactivity with red cell membranes. All erythrocytes tested (bird and mammal red cells were used) and rat thymocytes were phagocytosed by rat macrophages after incubation with aldehyde. Treatment of Candida albicans did not induce phagocytosis: this failure was not due to lack of aldehyde binding (as demonstrated with [14C]-methanal) nor to anti-phagocytic properties of the parasite membrane. Sheep erythrocytes were submitted to enzymatic treatment (pronase, trypsin, neuraminidase) or incubated with succinic anhydride (to block free NH2 groups) or iodacetamide (to block free SH groups) before aldehyde treatment: phagocytosis was not decreased, which suggested that aldehydes did not act by altering some definite surface structure of the treated particles. Treatment of erythrocytes with cross-linking compounds such as tetraazotized o-dianisidine (coupling occurs mainly on tyrosine and histidine residues) or l-ethyl(3-dimethyl aminopropyl) carbodiimide (a bivalent reagent binding free COOH groups) did not induce any substantial phagocytosis of erythrocytes. Phagocytosis of aldehyde treated erythrocytes was partly correlated with hydrophobicity of these cells, as measured with a two-phase partition system. It is concluded that aldehyde-mediated phagocytosis of erythrocytes is mainly due to cross-linking of red cell membrane structures, probably involving free OH groups, which must increase local rigidity and thereby modify hydrophobicity of the red cell surface.

Aldehydes↗
PubMed1978

Dependence of phagocytosis on strength of phagocyte-particle interaction.

Sheep erythrocytes were pretreated with concanavalin A (Con-A-SRC), or glutaraldehyde (G-SRC), or specific rabbit immunoglobulin G (IgG-SRC), or specific rabbit immunoglobulin M and complement (C-SRC). Each erythrocyte type was made to adhere to rat peritoneal cells and adhesion was measured; binding decreased as follow: conA-SRC greater than IgG-SRC greater than less than G-SRC greater than C-SRC Peritoneal cell-erythrocyte complexes were then submitted to a laminar shear flow, and resistance of binding was assayed. Binging strength decreased in the following order: G-SRC greater than C-SRC greater than IgG-SRC greater than ConA-SRC Cell suspensions were incubated at 37 degrees, and phagocytosis was measured. Ingestion decreased in the following order: G-SRC greater than IgG-SRC greater than C-SRC greater than ConA-SRC It is concluded that: Binding strength may be of importance in triggering phagocytosis; when immunocytoadherence is studied, two independent parameters should be considered: binding and binding strength. This report describes a new method that may allow discrimination between different cell subpopulations of similar binding specificities.

Animals↗
PubMed1977

Evidence for suppressor cells in Lewis rats' experimental allergic encephalomyelitis.

In this work we demonstrate a suppressive activity on the induction of experimental allergic encephalomyelitis (EAE) in Lewis rats, transferable to syngeneic animals, challenged with encephalitogenic mixture (myelin basic protein, complete Freud's adjuvant plus Bordetella pertussis organisms) 24 h later. This activity is probably effected by T cells and not by (an) inhibitory serum factor(s). The induction of this specific protection could be due to the penetration of the myelin basic protein antigen into the thymus where we first found suppressive cells. From the thymus, suppressor cells could then emigrate to spleen (on day 15) and to nondraining lymph nodes (on day 17). In the course of normal EAE in Lewis rats and especially at the time of self cure, this suppression is not demonstrated, but possible.

Animals↗
PubMed1976

What can be measured with RAST?

A theoretical study of the basic principles involved in Radioallergosorbent test (RAST) showed that: 1) When a given serum is tested, the significance of the numerical value obtained with RAST depends upon the serum assayed and the allergosorbent preparation, in a rather unpredictable way. Three factors can be measured: a) The percentage of specific IgE antibodies among all allergen-specific antibodies; b) The specific IgE antibody level; c) The product of the specific IgE antibody level and its affinity constant. 2) Simple graphical techniques allow a straightforward determination of all these factors if four dilutions of each serum are assayed at the same time. The results are expressed in two constant parameters (arbitrary IgE unit and allergosorbent capacity). It is concluded that these theoretical calculations may give a fair account of a lack of correlation between specific IgE antibody levels (as assayed with RAST) and several clinical and biological parameters. Furthermore, they provide a simple procedure which makes such tedious manipulations as specific IgE antibody purification quite necessary.

Absorption↗
PubMed1975

Effect of concanavalin A on membrane-bound enzymes from mouse lymphocytes.

The ionic influence and ouabain sensitivity of lymphocyte mg-2+-atpase and Mg-2+-(Na+ +K+)-activated ATPase were studied in intact cells, microsomal fraction and isolated plasma membranes. The active site of 5'-nucleotidase and Mg2+-ATPase seemed to be localized on the external side of the plasma membrane whereas the ATP binding site of (Na+ +K+)-ATPase was located inside the membrane. Concanavalin A induced an early stimulation of Mg2+-APTase and (Na+ +K+)-ATPase both on intact cells and purified plasma membranes. In contrast, 5'-nucleotidase activity was not affected by the mitogen. Although the thymocyte Mg2+-ATPase activity was 3-5 times lower than in spleen lymphocytes, it was much more stimulated in the former cells (about 40 versus 20%). (Na+ +K+)-ATPase activity was undectectable in thymocytes. However, in spleen lymphocytes (Na+ +K+)-ATPase activity can be detected and was 30% increased by concanavalin A. Several aspects of this enzymic stimulation had also characteristic features of blast transformation induced by concanavalin A, suggesting a possible role of these enzymes, especially Mg2+-ATPase, in lymphocyte stimulation.

Adenosine Triphosphatases↗