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J R David

Publications and source records attributed to J R David.

At least 163 records · Page 9Linked to original sources
PubMed1981

Cell-mediated cytotoxicity to Trypanosoma cruzi. II. Antibody-dependent killing of bloodstream forms by mouse eosinophils and neutrophils.

Mouse mononuclear cells, neutrophils, and eosinophils were tested for their capacity to mediate antibody-dependent cytotoxicity against bloodstream trypomastigotes of Trypanosoma cruzi. Granulocyte populations were found to be far more effective than nonadherent mononuclear cells in an in vitro assay in which the number of motile parasites was measured. Eosinophils and neutrophils were observed to be equally efficient on a cell-per-cell basis in killing the trypomastigotes. These results were verified in parallel experiments in which trypomastigotes, after incubation with antibody and effector cells, were reinjected into susceptible mice and the survival of the animals was determined.

Animals↗
PubMed1981

Studies on human migration inhibitory factor: characterization of three molecular species.

Human migration inhibitory factor (MIF), obtained from supernatants of peripheral blood mononuclear cells stimulated with concanavalin A, was analyzed by gel filtration, isoelectrofocusing, and CsCl density gradient centrifugation. A distinct pattern of heterogeneity was determined on the basis of its harvesting time and biochemical criteria. Supernatants from cells cultured for 1 day contained a single peak of MIF activity with an isoelectric point of 4.3 to 5.2, an apparent m.w. of 23,000, and a density of 1.314 g/ml, the same as the density of the marker protein, 125I-HSA (1st day pH 5-MIF). Furthermore, this species of human MIF was sensitive to treatment with trypsin, strongly suggesting its being a protein, but not to treatment with neuraminidase and corresponds therefore to guinea pig pH 5-MIF. However, when 2nd day supernatants were analyzed under the same conditions, 2 MIF species were found. One species with an isoelectric point of 2.4 to 3.3 had an apparent m.w. of 65,000 (2nd day 3-MIF). The other species with an isoelectric point of 4.3 to 5.6 had an apparent m.w. of 23-43,000 (2nd day pH 5-MIF). Upon centrifugation in CsCl density gradients, the density (rho 25 of 1.314 to 1.414 g/ml) of both species was found to be greater than that of the pure protein, 125I-HSA. In addition, both species were chymotrypsin and neuraminidase sensitive but not trypsin sensitive, further suggesting their glycoprotein nature.

Animals↗
PubMed1981

In vitro killing of S. mansoni schistosomula by lymphokine-activated mouse macrophages.

Inflammatory macrophages from mice i.p. injected with FCS 24-hr before harvesting, activated by partly purified MAF from Con A-stimulated spleen cells, were shown to kill an average of 60.9% (SE +/- 5.3) of the parasites in cultures of Schistosoma mansoni schistosomula. On the contrary, resident macrophages were not cytotoxic under the same conditions. The degree of macrophage activation for the killing was dependent upon both lymphokine concentration and time of incubation in lymphokine. The capacity of macrophages to be activated to kill schistosomula as well as the schistosomulicidal activity of the lymphokine-activated macrophages were short-lived properties. The killing was strongly influenced by the effector-to-target ratio. The results are consistent with other data on the immune response in experimental infection and particularly the development of the delayed hypersensitivity. Therefore, among the immune mechanisms that participate in immunity to reinfection, cell-mediated immunity that involves inflammatory macrophages should no longer be restricted to microorganisms and protozoans and could be extended to multicellular parasites like schistosomes.

Animals↗
PubMed1980

Enhanced helminthotoxic capacity of eosinophils from patients with eosinophilia.

To determine whether eosinophils from patients with eosinophilia have an enhanced capacity to kill parasites, we compared purified eosinophils (mean purity, 89 per cent) from 30 patients with various degrees of eosinophilia and with or without infection with Schistosoma mansoni for the capacity to kill schistosomula, the larval stage of S. mansoni, in vitro. There was a significant correlation between peripheral eosinophil count and antibody-dependent, eosinophil-mediated death of parasites after 40 hours of culture (P < 0.0001). Antibody-dependent adherence of eosinophils, measured after two hours of incubation, also correlated with the capacity of the eosinophils to kill the parasites. The correlation between the killing capacity of eosinophils and their peripheral-blood count was observed in patients both with and without S. mansoni infection. We suggest that eosinophilia involves not only a quantitative change in eosinophil numbers but also a qualitative change in functional capacity that renders circulating eosinophils more effective in resisting parasitic infections.

Antibodies↗
PubMed1980

Gold does not alter the arthritic, humoral, or cellular responses in rats with type II collagen-induced arthritis.

We assessed the effects of administration of gold sodium thiomalate on the clinical and immunologic manifestations of type II collagen-induced arthritis in rats. Injections of varying doses of gold did not alter these parameters significantly. Thus, there was no evidence in this animal model that gold possesses either antiinflammatory or immunosuppressive properties.

Animals↗
PubMed1980

Effect of psychological stress on the induction of arthritis in rats.

To determine whether emotional states could influence susceptibility to type II collagen-induced arthritis in rats, we studied the effects of experimentally produced psychological stress on the clinical, histologic, and immunologic manifestations of this autoimmune disease. Stress, induced by exposure to a cat, abrogated the development of arthritis in rats immunized with type II collagen. The incidence of arthritis was also decreased in rats subjected to transportation and handling. These environmental factors dissociated the development of humoral and cellular sensitivity to collagen from the occurrence of arthritis. This study provides a unique demonstration that psychosomatic processes can influence an animal mode of autoimmunity.

Animals↗
PubMed1980

Alcohol tolerance and alcohol utilisation in Drosophila: partial independence of two adaptive traits.

Three natural populations of D. melanogaster with different ethanol tolerance, and a population of D. simulans were successfully selected for an increased capacity to withstand alcohol. Alcohol utilisation, measured by the increase of life duration in the presence of low concentrations of alcohol, was clearly improved only in two cases. Alcohol tolerance and utilisation, two physiological traits that both depend on the presence of an active ADH, are thus controlled, at least partly, by different genetic mechanisms. In Drosophila species breeding on fermenting fruits or in wine cellars, both traits may be under the control of natural selection.

Alcohol Oxidoreductases↗
PubMed1980

The adherence of human neutrophils and eosinophils to schistosomula: evidence for membrane fusion between cells and parasites.

Human neutrophils and eosinophils adhere to the surface of schistosomula of Schistosoma mansoni that have been preincubated with antischistosomular sera with or without complement. Neutrophils are seen to form small (< 0.5 micrometer), heptalaminar and large (5-8 micrometer), pentalaminar fusions with the normal pentalaminar parasite surface membrane. By freeze-fracture techniques, attachment areas 5-8 micrometer in diameter are seen to form between neutrophils and schistosomula. These areas have three zones--an edge and two centrally located areas, one of which is rich and one of which is poor in intramembrane particles (IMPs). The edge zone is continuous around the attachment areas and is usually composed of a skip-fracture that passes out of the schistosomular outer membrane into the inner membrane. In some cases, the edge zone is made up of a string of IMPs. The IMP-rich central areas have an IMP concentration similar to that of unattached neutrophil membranes, are raised off of the surface of the schistosomulum, and have two normal schistosomular membranes underneath indicating that they are indeed unattached. the IMP-poor central areas are composed of a fused or hybrid membrane that is continuous with the neutrophil plasma membrane but that bears the same spatial relationship to the schistosomular inner membrane that the normal outer membrane does. Similar changes are seen in samples prepared with glycerination. Eosinophils generally do not fuse with the schistosomular outer membrane but, instead, discharge their granular contents onto the surface of the schistosomula and appear to adhere to the parasite through this discharged material. It is suggested that schistosomula have a capability to fuse with mammalian cells and that this fusion proceeds from a fusion of the outer leaflets to a fusion of the bilayers, as appears also to be the case in other systems.

Animals↗
PubMed1980

Partial and complete detachment of neutrophils and eosinophils from schistosomula: evidence for the establishment of continuity between a fused and normal parasite membrane.

Neutrophils and eosinophils adhering to the surface of schistosomula of Schistosoma mansoni have been partially or completely detached with hypertonic sucrose or by pipetting. The sucrose-treated neutrophils are attached only in areas where there are pentalaminar fusions between the neutrophil and tegumental membranes, suggesting that these fusions attach the cells to the parasites. Pipetting breaks many of the attached cells. In thin section, the tegumental membrane underlying these cells is seen to be pentalaminar. By freeze-fracture techniques, modified attachment areas are found. The edge zone often appears as a single strand of intramembrane particles (IMPs) on the P2 face and as a groove on the E2 face. The edge zone may also have large discontinuities, in which case it no longer separates membrane faces of unequal IMP density from one another. In addition, the IMPs on the IMP-rich areas become aggregated and surrounded by craters in the membrane. These experiments suggest that the fusions may be the mechanism by which the parasite acquires some host membrane components on its surface. On the other hand, eosinophil plasma membranes are seen adhering to a layer of electron-dense material on the parasite after the cells have been disrupted by pipetting. This suggests that eosinophils adhere to the parasite surface through their discharged granule material and not by membrane fusions.

Animals↗
PubMed1980

Autoimmunity to collagen in adjuvant arthritis of rats.

Arthritis can be induced in rats by intradermal injection of oil containing bacterial derivatives (adjuvant-induced arthritis) or cartilage collagen (type II collagen-induced arthritis). It was of interest, therefore, to determine whether collagen functions as an autoantigen in rats with adjuvant arthritis. Blood mononuclear cells from the majority of rats with adjuvant arthritis exhibited enhanced thymidine incorporation to homologous types I and II collagens, as well as to purified protein derivative of tuberculin. In contrast, cells from rats remaining nonarthritic after injection of adjuvant did not respond to collagen, although they did react to tuberculin. Similar results were obtained with a radiometric ear assay used to quantify intradermal delayed-type hypersensitivity in vivo. Using passive hemagglutination, autoantibodies to these collagens and their denatured alpha-chains were frequently detected in the sera of rats late in the course of adjuvant arthritis. Rats with inflammation of a hindlimb induced by turpentine did not acquire sensitivity to collagen. These data indicate that autoimmunity to collagen is a common feature of adjuvant- and collagen-induced arthritis, both of which are considered to be mediated by immunologic mechanisms.

Animals↗