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Biomedical subjects

M M Philippeaux

Publications and source records attributed to M M Philippeaux.

7 recordsLinked to original sources
PubMed1996

Activated human platelets express beta2 integrin.

The expression of molecules of the beta2 integrin family (CD11a, CD11b , CD11c, and CD18) was explored on 2 human megakaryocytic cell lines and on platelets from different donors by immunofluorescence and flow cytometry using a large panel of mAb. CD11a, CD11b, CD11c and CD18 were detected on the megakaryocytic cell lines DAMI and HEL. A low and variable expression of CD11a, CD11b and CD18 determinants was also detected on resting platelets; this expression was markedly increased when platelets were activated by thrombin. Expression of CD18 was closely correlated to that of CD11a or CD11b when comparing the fluorescence intensity observed in different experiments. In presence of Ca++, platelets did bind to a RAJI cell line which exhibits a high expression level of CD54. This binding was increased when platelets were activated by thrombin and was decreased by an anti CD11a, CD18 and anti CD54 mAb. This study indicates that human platelets express molecules of the beta2 integrin family, when activated, which allows them to bind to CD54 bearing cells.

Animals↗
PubMed1994

Cytostatic activity of alveolar macrophages from smokers and nonsmokers: role of interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha.

Several functions of alveolar macrophages (AM) are modified by cigarette smoking. AM are the first line of defense in bronchoalveolar spaces and could be depressed in their cytotoxicity to tumor cells in smokers. An assay using A549 cells (human lung adenocarcinoma) as target cells was performed to assess cytostasis mediated by AM and their supernatants (SN) from healthy smokers (n = 8) and nonsmokers (n = 6). Contact-mediated cytostasis was decreased in AM of smokers (n = 8) relative to nonsmokers (n = 6) (22.9 +/- 5.7% versus 42.7 +/- 6.0% [+/- SEM], P < 0.04) and increased after lipopolysaccharide (LPS) stimulation in both groups (34.5 +/- 5.3% versus 46.8 +/- 5.2%, NS). Cytostasis induced by SN from nonstimulated AM was low in both groups and was still lower in smokers after LPS exposure (19.3 +/- 4.5% versus 34.5 +/- 4.8%, P < 0.04). Among cytotoxic factors produced by macrophages, interleukin (IL)-1 beta, IL-6, and tumor necrosis factor alpha (TNF alpha) may play an important role in cytostasis. Recombinant human (rH) IL-1 beta and rHTNF alpha had a moderate cytostatic activity, which was additive, whereas rHIL-6 had no significant activity on A549 cells. Bioactive IL-1 beta, IL-6, and TNF alpha were therefore measured in macrophage SN. Their levels tended to be lower in smokers than in nonsmokers and were much increased after LPS stimulation. Levels of the three cytokines were also found to correlate with each other; furthermore, a good correlation between cytokine levels in SN and cytostasis was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1993

Expression of tumor necrosis factor-alpha and its mRNA in the endometrial mucosa during the menstrual cycle.

Endometrial biopsies, collected at various phases of the menstrual cycle, were examined for the presence of tumor necrosis factor-alpha (TNF-alpha) by histochemistry, and TNF-alpha mRNA by in situ hybridization and Northern blotting. During the proliferative phase, TNF-alpha and TNF-alpha mRNA were not detected or were at low levels. During the secretory phase, the TNF-alpha mRNA level was increased and observed in the wall of coiled arteries. TNF-alpha was detected both in the wall of the coiled arteries and, in highest concentration, within the epithelial cells. In regard to the capacity of TNF-alpha to induce a hemorrhagic necrosis in various tissues, this study suggests that an overproduction of TNF-alpha within the small arteries of the endometrial mucosa might be responsible for menstruation.

Adult↗
PubMed1992

Protodyne: an immunostimulatory protein component, prepared from gram-positive Bacillus subtilis.

A protein component derived from bacterial protoplasm, called Protodyne, increases the non-specific resistance to infections by bacteria and viruses. Here we show that Protodyne can be prepared not only from Gram-negative bacteria, but also from Gram-positive bacilli. Several preparations of Protodyne, prepared from Bacillus subtilis by phenol extraction or by ammonium sulfate precipitation, were evaluated for immunomodulatory activities in a variety of assays. Protodyne had a marked mitogenic activity on mouse spleen cells; it was a potent inducer of tumor necrosis factor (TNF) and stimulated production of interleukin-1 (IL-1) in human peripheral blood mononuclear cells; it increased the capacity of activated macrophages to undergo a respiratory burst, to produce intracellular killing of leishmanial parasite and extracellular lysis of mastocytoma cells; it also stimulated phagocytosis of latex particles, and prolonged survival of immunosuppressed mice infected with Pseudomonas aeruginosa. These activities were not inhibited by polymyxin B, indicating that the activity of Protodyne is not the result of contamination with exogenous lipopolysaccharide. It appears that Protodyne exerts its many immunomodulatory actions by inducing the release of soluble mediators, including TNF and IL-1.

Adjuvants, Immunologic↗
PubMed1984

Extracellular cytolysis by activated macrophages: studies with macrophages on permeable membranes.

Mouse peritoneal macrophages were allowed to adhere to discs cut from permeable membranes, then activated by incubation in lymphokine-rich supernates from ConA-stimulated spleen cells. Such filter-borne cultures of activated macrophages (AM) were cytotoxic for various target cells (Tc). The kinetics of the cytotoxic process could be monitored by removal of the filter-bound AM after increasing times of contact with Tc. Using 3 assay procedures to assess macrophage cytotoxicity, i.e. chromium-51 release, thymidine incorporation, and cloning inhibition, most of the damage to Tc was found to occur within 30 min to 2 h of interaction between the two cell types. The kinetics of the cytolytic effect were similar, whether Tc were in direct contact with AM or separated by the filter; thus cytotoxicity appeared to be mediated by a highly diffusible compound. Supernates of AM incubated with Tc for 1 to 4 h, but not of AM incubated alone, were toxic for Tc, suggesting that Tc provide a signal to AM, in the absence of which toxic intermediates fail to be released. Addition of catalase or peroxidase considerably reduced Tc destruction by AM, indicating that oxygen metabolites might play a role as mediators of AM cytotoxicity in the present experimental model.

Animals↗
PubMed1981

Membrane particle arrays in SV40-transformed 3T3 cells.

The ultrastructural organization of the plasma membrane of untransformed and simian virus (SV)40-transformed 3T3 cells in culture was studied by an in situ freeze-fracturing technique. Both 3T3 and SV3T3 cells showed randomly distributed intramembrane particles as well as gap junctions. In addition, the plasma membrane (P-face) of confluent SV40-transformed 3T3 cells was found to display a unique membrane specialization which was not observed in normal 3T3 cells. This membrane specialization consisted of irregularly-shaped arrays of loosely dispersed large (11-12 nm) intramembrane particles, located in regions of close contact between adjacent SV3T3 cells. When a P- to E-fracture face transition occurred within the boundaries of a particle array, the intracellular space appeared uniformly reduced and arrays of pits coextensive with the P-face particles could be recognized on the E-face. Particle arrays appeared particularly prominent in SV3T3 cells grown in the presence of high serum concentrations (20% foetal calf serum or calf serum). Particle arrays resembling those found in SV3T3 cells were observed only in very rare instances in the plasma membrane of other virus-transformed cell lines. Several possible interpretations of the meaning of the particle arrays, including the hypothesis thay they represent an unusual or abortive form of intracellular junction, are discussed. The absence of similar membrane specializations in the plasma membrane of untransformed 3T3 cells points to a difference in membrane organization and cell contact ultrastructure between normal and SV40-transformed 3T3 cells.

Animals↗