| 1. |
- Ramos, O F, et al.
(författare)
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Alternative pathway of complement activation by stimulated T lymphocytes. II. Elevation of cytotoxic potential against complement receptor-carrying cell lines.
- 1987
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 17:7, s. 975-979
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Tidskriftsartikel (refereegranskat)abstract
- Exposure of lectin-stimulated (concanavalin A, phytohemagglutinin and pokeweed mitogen) blood lymphocytes to human serum or to purified C3 increased their cytotoxic capacity towards complement receptor positive targets such as Raji and Daudi cells. The lysis of complement receptor-negative lymphoblastoid cell lines was not influenced. The lytic capacity of lymphocytes exposed to 12-O-tetradecanoylphorbol 13-acetate was not elevated by human serum. Lectin-stimulated lymphocytes were previously shown to activate and bind C3. The results using lymphocytes activated in different ways and targets with or without complement receptor expression suggest that the C3b deposited on lymphocytes binds to the complement receptor on the targets. This contact elevates the avidity between the two cells as indicated also by the increased frequency of the lymphocyte-target conjugates. On the basis of immune adherence the C3 fragment bound on the lymphocytes was identified as C3b. The increase of the conjugate formation and cytotoxicity was abrogated when the target cells, Raji, were pre-exposed to purified C3d which occupy the CR2 receptor. The majority of lymphocytes responsible for the cytotoxicity were CD8+.
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| 2. |
- Ramos, O F, et al.
(författare)
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Elevated NK-mediated lysis of Raji and Daudi cells carrying fixed iC3b fragments
- 1989
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Ingår i: Cellular Immunology. - 0008-8749 .- 1090-2163. ; 119:2, s. 459-469
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Tidskriftsartikel (refereegranskat)abstract
- Raji and Daudi cells were opsonized with C3b, iC3b and C3d fragments by using purified complement components. The sensitivity of C3-opsonized cells to lysis mediated by low density blood lymphocytes was studied. Raji and Daudi cells carrying C3b or C3d fragments were lysed with similar efficiencies as the nonopsonized cells. The presence of iC3b on the target surface imposed elevated NK sensitivity. The iC3b-mediated enhancement of NK lysis was inhibited when iC3b fragments or rabbit anti-human C3 antibodies were included into the lytic assays. These results indicate that the iC3b fragments fixed on the targets bind to the CR3 on the lymphocytes. Results obtained in immobilized conjugate-lytic assays showed that iC3b-opsonized targets interact more readily with the lymphocytes. This was reflected by the elevated proportion of lymphocytes that were bound to the iC3b-carrying targets. The proportions of conjugates in which target damage occurred were similar with the control and with the iC3b-carrying cells. It seems therefore that opsonization of targets with iC3b leads to recruitment of effector lymphocytes due to contact with their CR3. However, once the effector-target contact is established, the triggering of lytic function does not seem to be influenced by the iC3b/CR3 bridge.
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| 3. |
- van Veen, Theo, et al.
(författare)
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Retinal S-antigen: immunocytochemical and immunochemical studies on distribution in animal photoreceptors and pineal organs
- 1986
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Ingår i: Experimental Biology. ; 45, s. 15-25
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Tidskriftsartikel (refereegranskat)abstract
- Antiserum against bovine retinal S-antigen, a soluble protein (MW = 50 kDa) thought to be involved in phototransduction, was used in an immunohistochemical and immunochemical study of vertebrate eyes and pineal systems and invertebrate photoreceptor organs. Positive reactions, not seen with antiserum preabsorbed with highly purified S-antigen, were observed in planarian and starfish ocelli; scallop eyes; polychaete eye; crayfish compound eye; lamprey, salmon, frog, turtle, quail and hamster eyes. A specific reaction was also seen in the pineal organ of all the vertebrates examined, albeit weak in turtle and quail. In addition, several structures associated with photoreceptor organs, including the reduced frontal eyes of crayfish, the organ of Bellonci in crayfish eyestalk, and bipolar cells resembling those giving rise to Landolt's clubs in quail and golden hamster retinae, were immunopositive. Immunochemical studies revealed the presence of a single immunopositive band of protein which was similar but not identical in size in all vertebrate eyes and pineal organs (except that of chicken pineal) and invertebrate tissue examined. The wide distribution of positive reaction in photoreceptive tissue indicates that the retinal S-antigen determinant has been highly conserved during evolution.
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| 4. |
- Zoback, Mary Lou, et al.
(författare)
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Global patterns of tectonic stress
- 1989
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 341:6240, s. 291-298
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Forskningsöversikt (refereegranskat)abstract
- Regional patterns of present-day tectonic stress can be used to evaluate the forces acting on the lithosphere and to investigate intraplate seismicity. Most intraplate regions are characterized by a compressional stress regime; extension is limited almost entirely to thermally uplifted regions. In several plates the maximum horizontal stress is subparallel to the direction of absolute plate motion, suggesting that the forces driving the plates also dominate the stress distribution in the plate interior.
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