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  • 1
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mouse IgG2a and IgG3 antibodies directed to the human T-cell receptor/CD3 complex stimulate peripheral blood mononuclear cells in almost all individuals. By contrast, responder and non-responder individuals exist for the stimulatory effect of mouse IgG1 and IgG2b antibodies. Whereas responsiveness to IgG1 antibodies is rather frequent (60–70%) and is known to be determined by an FcγRII polymorphism on the accessory cells, little is known about the underlying factors of the rare (6%) IgG2b responsiveness. In this study it is shown that (1) IgG2b responsiveness is genetically determined with a dominant pattern of inheritance; (2) IgG2b responsiveness is determined by a radioresistant feature of responder accessory cells which can be substituted by artificial cross-linking, but not by IL-1β or IL-2; (3) stimulation of peripheral blood mononuclear cells of an IgG2b responder by IgG2b antibodies requires rather high antibody concentration compared with stimulation by IgG2a antibodies; (4) the stimulation leads to proliferation and IL-2 receptor expression, but no measurable IL-2 production; (5) antibody binding to known Fey receptors (FcγRI, FcγRII, FcγRIIT) is not involved in the stimulatory effect of the IgG2b antibodies in responders. These results demonstrate that responsiveness to IgG2b antibodies against the TcR/CD3 complex depends on a genetically determined feature of accessory cells that is not identical with any of the known Fcγ receptors. Most likely, the stimulatory effect observed in IgG2b responders is explained by a low grade cross-Unking of the antibody by a not yet identified polymorphic structure on the surface of accessory cells.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 31 (1990), S. 0 
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Removal of the largest single lymphoid organ, the spleen, leads to an increase in severe infections. To prevent this, transplantation of splenic fragments can be performed, which may, however, cause an increase in CD8+ lymphocytes in the blood of these patients. This is controversial since in the clinical situation it is often difficult to account for the different age of the patients, the time point after the operation and many other factors known to influence the number of lymphocyte subsets.Using a well-defined animal model, B, T, CD4+, and CD8+ lymphocytes were determined preoperatively in adult rats. Then, either sham splenectomy, splenectomy, or splenic autotrans-plantation was performed and the animals were followed up for 15 months after the operation.The surgical procedure itself, the site of blood sampling and ageing all influenced the number of lymphocyte subsets profoundly. Furthermore, giving the data as relative or absolute numbers leads to different results.Splenectomy caused lymphocytosis, due to a significant increase in B and CD8+ lymphocytes, as did splenic autotransplantation, which indicates that the number of lymphocyte subsets in the blood should not be used to argue in favour of or against splenic autotransplantation.This study demonstrates that the number of lymphocyte subsets in the blood is influenced by many factors and therefore should be determined in a highly standardized fashion.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 32 (1990), S. 0 
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: BMA031 is an IgG2b antibody directed towards the human α/β T-cell receptor that is able to induce proliferation of peripheral blood mononuclear cells independent of antibody cross-linking. The proliferative response to BMA031 during the first 1 days of culture is usually of similar magnitude lo that induced by the IgG2a CD3 antibody OKT3 but decreases quickly afterwards. Stimulation by BMA031 induces no measureable IL-2 release, very low expression of the IL-2 receptor, and does not trigger cytotoxic effector function. However, cross-linking of the antibody or addition of IL-2 leads So enhanced and prolonged proliferation, strong IL-2 receptor expression, and cytotoxic activity, features that are usually found after Stimulation by the IgG2a CD3 antibody OKT3 in soluble form. The stimulatory effect of BMA031 cannot be diminished by IL-2 receptor blocking, whereas stimulation by OKT3 is strongly reduced Moreover, proliferation induced by BMA031 has lower sensitivity to inhibition by ciclosporin than OKT3. From these results two major conclusions can be drawn: (I) an IL-2-independent way of activation may be important for the short-term proliferation of the T cells stimulated by BMA031 and (2) after stimulation by BMA031. cells reach a state of activation that is different from that induced by OK.T3. These differences arc most likely related to the different specificities of the antibodies, α/β TcR versus CD3, suggesting that different activation signals are triggered via CD3 and via the α/β TcR.
    Type of Medium: Electronic Resource
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