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Biomedical subjects

J M Cavaillon

Publications and source records attributed to J M Cavaillon.

At least 109 records · Page 6Linked to original sources
PubMed1984

Interleukin 1 secretion by human monocytes stimulated by the isolated polysaccharide region of the Bordetella pertussis endotoxin.

The isolated polysaccharide chain, PS-1, of the Bordetella pertussis endotoxin was examined by isoelectric focusing, SDS-polyacrylamide gel electrophoresis and gel filtration for heterogeneity and for possible contamination by the parent endotoxin. This polysaccharide, previously found to be a very potent, macrophage-dependent, polyclonal B-cell activator and to mediate the specific binding of the endotoxin to macrophages, stimulated the interleukin 1 (IL 1) secretion by human monocytes; its potency was similar to that measured for the endotoxin. It was concluded that endotoxin-induced IL 1 production may be initiated by the interaction of the polysaccharide chain of the B. pertussis endotoxin and a specific structure present on macrophages.

Adult↗
PubMed1984

Presence of IL 1 activity in the supernatant of human monocytes challenged with purified allergenic constituents.

Purified allergenic constituents from Dermatophagoides farinae mite (Df 11 and Df 6) and from orchard grass (Dactylis glomerata) pollen (F 34) are able to trigger, in the absence of IgE and IgG antibodies, human adherent cells, leading to the secretion of interleukin 1, (IL 1). This secretion was observed with adherent peripheral blood mononuclear cells from normal donors as well as from atopic patients. The IL 1 activity was evaluated by the mice thymocyte mitogenesis in the presence of suboptimal doses of Con A. The secretion of IL 1 by adherent cells was not affected by a cytotoxic treatment with OKT3 monoclonal antibody in the presence of complement, implying a direct action of allergenic fractions, on monocytes, and not through a T-cell pathway. The challenge of human monocytes with allergens in the presence of indomethacin led to culture supernatants for which a higher 3H-thymidine incorporation by mice thymocytes was detected; thus, purified allergens could also trigger the secretion of prostaglandins by human monocytes.

Animals↗
PubMed1983

Polyclonal antibody-forming cell activation and immunomodulation of the in vitro immune response induced by streptococcal extracellular products.

The capacity of three different extracellular streptococcal products to induce polyclonal activation of precursors of plaque-forming cells (PFC) was investigated. The gamma fraction (pI = 4.2), previously shown to be only weakly mitogenic, was the most potent activator of rabbit and mouse immunoglobulin-secreting cells. The polyclonal stimulation induced by the two other fractions (kappa: pI = 4.8 and epsilon: pI = 10.3), shown to be mitogenic in both systems, was only observed in the rabbit system. Using these fractions, the in vitro immunomodulation of the anti-sheep red blood cell immune response was also investigated. Both gamma and epsilon fractions were shown to possess adjuvant properties, whereas the kappa fraction was a suppressor of the specific immune response. It appears, therefore, that the diversified immunological activities observed with extracellular streptococcal products can be dissociated and belong to different entities.

Animals↗
PubMed1982

[Role of bacterial polyclonal activators in autoimmunity].

Polyclonal activation of lymphocytes constitutes a non-specific stimulation resulting in the production and secretion by these cells of biologically active molecules, including antibodies. Polyclonal activation of human and animal lymphocytes can be observed, usually in vitro, with many active macromolecules of bacterial origin (surface constituants or excreted compounds). It is a complex phenomenon which may involve several cell populations (B-lymphocytes, T-lymphocytes, macrophages, etc.) and numerous mediators (lymphokines, monokines, etc.). An ever increasing collection of data suggests that polyclonal activators induce the synthesis of a variety of antibodies directed against the host (auto-antibodies). The relationship between auto-immune diseases and the presence of polyclonal activators in situ is discussed.

Animals↗
PubMed1982

Mitogenicity of streptococcal extracellular products and antagonism with concanavalin A.

Extracellular products have been purified from group A Streptococcus pyogenes culture supernatant fluids and their mitogenicities have been tested on rabbit and mouse lymphocytes. Two fractions were mitogenic: the kappa-fraction (pI = 4.8, mol. wt. = 30,000), a protein which was identified as the erythrogenic toxin, and the epsilon-fraction (pI = 10.3, mol. wt. = 17,000) a glycoprotein, both stimulated rabbit and CBA mouse spleen cells. The stimulation of rabbit thymocytes was weak unless macrophages or 2-mercaptoethanol were added. A third product, the gamma-fraction (a protein, pI = 4.2, mol. wt. = 72,000) was very weakly mitogenic and had the capacity to reduce the stimulation induced by a T-cell mitogen, such as Con A, but not by a B-cell mitogen such as Nocardia.

Animals↗
PubMed1982

Induction of interferon by streptococcus pyogenes extracellular products.

Lymphocyte-activating streptococcal exoproteins, which were previously characterized, have been tested for their capacity to induce interferon in vitro. Two out of the 3 different streptococcal fractions, studied on mice splenocytes, were shown to elicit the production of a significant amount of interferon. A large proportion of the interferon detected in the supernatants from mice activated spleen cells was acid-labile interferon. The highest level of interferon titer was obtained with the streptococcal fraction identified as the erythrogenic toxin.

Animals↗
PubMed1982

Rabbit spleen B lymphocytes as helper cells in lymphocyte activation by concanavalin A and phytohaemagglutinin.

Using rosetting methods, we have purified rabbit B cells and studied their interactions with T cells purified by passage over an anti-immunoglobulin-coated Degalan beads column. B cells enhance the response of T cells to concanavalin A (Con A) and phytohaemagglutinin. In regulation of the response to Con A, an adherent cell is a third participating cell. B-cell preparation contain a minority of cells that can respond to T mitogens with the help of non-proliferating T cells, but the proportion of these responding cells is small, and the involvement of the T-cell impurity cannot be excluded.

Animals↗
PubMed1982

Selective cytotoxicity of Clostridium perfringens delta toxin on rabbit leukocytes.

Clostridium perfringens delta toxin was selectively cytotoxic for various rabbit leukocyte populations. The sensitivity of these populations to the toxin varied, depending on the tissue from which they were derived, from 28% (appendix) to 41% (bone marrow) and 32% (spleen). Macrophages were uniformly killed by delta toxin, whereas thymocytes were essentially resistant. Selective cytotoxicity was correlated to the specific binding of the radiolabeled toxin by target cells. The relationship between sensitivity to the toxin and the presence of GM2 ganglioside in the cell membrane of rabbit leukocytes is discussed. Delta toxin might prove a useful new tool for separating leukocyte subpopulations based on their differential sensitivity to the cytolethal effect of this protein.

Animals↗
PubMed1982

Lipopolysaccharide receptor on rabbit peritoneal macrophages. I. Binding characteristics.

The Bordetella pertussis endotoxin, labeled with tritium ((3H)-LPS), bound irreversibly and nonspecifically to rabbit lung macrophages, but bound reversibly and specifically to both resident and elicited rabbit peritoneal macrophages. The specific binding capacity of the macrophages was saturated with about 3 X 10(4) LPS molecules per cell. The binding was inhibited with the homologous unlabeled endotoxin, but not at all with endotoxin from Proteus mirabilis, thus assessing ligand specificity. Endotoxins from other bacteria gave intermediate inhibition value. Binding of tritium-labeled pertussis endotoxin was significantly inhibited by one of the two polysaccharides (PS-1) present in this endotoxin, but neither the other polysaccharide (PS-2) nor the Lipid A fragment exhibited such activity. These results strongly suggest the presence of a lectin-like receptor for LPS on the membrane of rabbit peritoneal macrophages.

Animals↗
PubMed1980

The effect of temperature-dependent autorosettes on B/T cell ratios of purified rabbit peripheral blood lymphocytes.

Contradictory reports as to B/T cell ratios in the peripheral blood lymphocytes (PBL) of rabbits led to an investigation of current purification methods. PBL prepared by sedimentation at 37 degrees C in gelatin solution showed the same B/T ratios as did whole blood. PBL prepared by the Ficoll-Hypaque method at 4 degrees C or at room temperature were enriched in B cells compared to the whole blood. This enrichment depended on the presence of autologous erythrocytes during centrifugation and it was not demonstrable when centrifugation was carried out at 37 degrees C. Resuspended red cell pellets contained more than 3 times as many rosette-forming cells if the pellets were obtained by centrifugation of blood on Ficoll at 4 degrees C rather than 37 degrees C. We, therefore, conclude that aggregation of T cells with autologous erythrocytes is responsible for the depletion of B cells in the PBL prepared by the Ficoll-Hypaque method at 4 degrees C or at room temperature.

Animals↗
PubMed1979

Purification of rabbit B spleen cells by removal of adherent and of T cells.

B lymphocytes from the rabbit spleen were freed of T cells by removal of cells which formed rosettes with papain-treated rabbit erythrocytes. Additional purification could be achieved if fractionation by rosette removal was preceded by removal with a magnet of cells which adhered to or ingested poly L-lysine coated iron core particles. Cell yield and purification were assessed by complement mediated cytotoxic kill of B and T cells with antibody directed against RABELA and RTLA, respectively. Other criteria depended on determination of the number of Fc receptor bearing cells and of thymidine uptake by cells which were stimulated with concanavalin A, PHA or with antibody directed against the allotypic specificity of receptor Ig light chains. Purified preparations of B cells were obtained in a yield of about 20% of the B cells in the original spleen and contained less than 10% of cells which were not B cells. This method allows purification which does not interfere with the membrane of the isolated cells.

Animals↗
PubMed1979

Rabbit B spleen lymphocytes and T helper cells. I. Responsiveness to mitogens of B cell subpopulations of different sedimentation velocities and subpopulations bearing or lacking Fcgamma receptors.

The response to anti-allotype (anti-Ab4), Nocardia Water Soluble Mitogen (NWSM), pneumococcal polysaccharide type III (SSS III), and human Fc fragments of various purified and unfractionated rabbit spleen cell populations was determined in terms of 3H-thymidine up-take. B cells were isolated either from untreated suspensions of spleen cells or from suspensions from which adherent and phagocytic cells were removed. The purification factor was greater than the enhancement of 3H-thymidine uptake by anti-Ab4, NWSM, and SSS III as compared with the response of unfractionated spleen cells. It thus appears that a helper cell was involved: the mitogen response of purified B cells was enhanced by the addition of T cells. B subpopulations were separated by sedimentation or by rosetting, which allowed us to separate Fcgamma receptor-bearing cells from cells that did not possess this receptor. There were differences between cells responding to B mitogens not only in sedimentation velocity but also in the absolute number of cells. B cells bearing the Fcgamma receptor were less responsive to anti-Ab4 and more responsive to SSS III, NWSM, and human Fc than were B cells lacking the Fcgamma receptor.

Animals↗
PubMed1977

Purification of rabbit T-derived (Ig-) lymphocytes.

Rabbit peripheral blood cells were rosetted by means of mixed agglutination technique described by Coombs et al. and the unrosetted Ig-, T-derived lymphocytes were separated in Ficoll-Triosil gradient. The cells which did not rosette in mixed agglutination reaction represented highly purified T-derived (Ig-) lymphocytes, as evidence by their response to T and B rabbit cell mitogens, their cytotoxic reactivity versus rabbit thymus lymphocyte antiserum (RTLA), and by failure to be stained with labelled anti-rabbit immunoglobulins antibodies and antibodies against allotypic specificities of the a and b series.

Animals↗