Search results for "major histocompatibility complex"
showing 10 items of 263 documents
An inherited deficiency of the third component of complement, C3, in guinea pigs
1986
Hereditary deficiency of the third component of complement, C3, is found very seldom in the human. C3 deficiency is associated with severe bacterial infections revealing the central role of C3 in complement activation via the classical or alternative pathway. We describe a new hereditary C3 deficiency in strain 2 guinea pigs. Serum from these animals had a markedly reduced lytic activity in a standard assay for complement-dependent, antibody-mediated cytotoxicity. In functional assays of individual components, the hemolytic activity of the components C4, C2, C5 and of factors B, D and H was in the normal range. The functional C3 titer, and similarly C3 antigenic activity in the serum of the…
Differences in non-MHC restricted cytotoxic activities of human peripheral blood lymphocytes after transfusion with allogeneic leukocytes or platelet…
1990
Abstract MHC-unrestricted cytotoxic activity of peripheral blood lymphocytes (PBL) from 4–6 healthy donors was investigated before and after transfusion with allogeneic leukocytes or platelets. Natural killer and lectin-dependent cellular cytotoxicity (LDCC) of PBL was tested against K562 and Raji target cells in a 4-h and 16-h 51 Cr-release assay, respectively. After allotransfusion with leukocytes, we found increased cytotoxic activity of each donor's PBL against all the three targets on day 3 or 7. The highest non-specific cytotoxic activity was detected against the relatively NK resistant Raji target cells. The increase of cytotoxic activity was lowest against the LDCC target (PHA-treat…
Catumaxomab: a bispecific trifunctional antibody.
2009
The trifunctional bispecific monoclonal antibody catumaxomab has two binding specificities directed at epithelial cell adhesion molecule (EpCAM) and the T-cell antigen CD3. With its Fc-fragment, catumaxomab additionally binds accessory cells such as dendritic cells, macrophages and natural killer cells. The trifunctional approach thus leads to unrestricted but specific killing of epithelial tumor cells by major histocompatibility complex without the need for preactivation or external costimulation. The tumor-associated antigen EpCAM is strongly expressed in carcinomas of various origins including colon, rectum, ovarian, gastric, esophagus, lung, pancreas, breast and head and neck. Expressio…
Tumor-specific T cell activation by recombinant immunoreceptors: CD3 zeta signaling and CD28 costimulation are simultaneously required for efficient …
2001
Abstract Recombinant immunoreceptors with specificity for the carcinoembryonic Ag (CEA) can redirect grafted T cells to a MHC/Ag-independent antitumor response. To analyze receptor-mediated cellular activation in the context of CD28 costimulation, we generated: 1) CEA+ colorectal tumor cells that express simultaneously B7-1 and B7-2, and 2) CEA-specific immunoreceptors that harbor intracellularly the signaling moities either of CD28 (BW431/26-scFv-Fc-CD28), CD3ζ (BW431/26-scFv-Fc-CD3ζ), or FcεRIγ (BW431/26-scFv-Fc-γ). By retroviral gene transfer, we grafted activated T cells from the peripheral blood with these immunoreceptors. T cells that express the FcεRIγ or CD3ζ signaling receptor lyse…
Analysis of parathyroid graft rejection suggests alloantigen-specific production of nitric oxide by iNOS-positive intragraft macrophages
2009
Abstract Background During acute rejection of organ or tissue allografts T cells and macrophages are dominant infiltrating cells. CD4-positive T cells are important for the induction of allograft rejection and macrophages are important effector cells mediating cytotoxicity via production of nitric oxide (NO) by the inducible NO-synthase (iNOS). In the present study we analysed whether the destruction of primarily nonvascularised parathyroid allografts is also mediated by iNOS-positive macrophages. Methods Hypocalcaemic Lewis rats received parathyroid isografts (from Lewis donors) and allografts (from Wistar Furth donors), respectively, under the kidney capsule. Levels of serum calcium above…
MHC class II tetramer guided detection of Mycobacterium tuberculosis-specific CD4+ T cells in peripheral blood from patients with pulmonary tuberculo…
2007
Novel diagnostic tools are needed to diagnose latent infection and to provide biologically meaningful surrogate markers to define cellular immune responses against Mycobacterium tuberculosis (MTB). Interferon gamma-based assays have recently been developed in addition to the more than 100-year-old tuberculin skin test (TST) for the immune diagnosis of MTB in blood. The advent of soluble MHC/peptide tetramer molecules allows to objectively enumerate antigen-specific T cells. We identified novel MHC class II-restricted MTB epitopes and used HLA-DR4 tetrameric complexes to visualize ex vivo CD4(+) T cells directed against the antigens Ag85B and the 19-kDa lipoprotein, shared between MTB and ot…
Ci8 short, a novel LPS-induced peptide from the ascidian Ciona intestinalis,modulates responses of the human immune system
2017
The selective modulation of immunity is an emerging concept driven by the vast advances in our understanding of this crucial host defense system. Invertebrates have raised researchers’ interest as potential sources of new bioactive molecules owing to their antibacterial, anticancer and immunomodulatory activities. A LipoPolySaccharide (LPS) challenge in the ascidian Ciona intestinalis generates the transcript, Ci8 short, with cisregulatory elements in the 3′ UTR region that are essential for shaping innate immune responses. The derived amino acidic sequence in silico analysis showed specific binding to human Major Histocompatibility Complex (MHC) Class I and Class II alleles. The role of Ci…
Glycoprotein 96-activated dendritic cells induce a CD8-biased T cell response.
2005
Heat shock proteins (Hsps) are able to induce protective immune responses against pathogens and tumors after injection into immunocompetent hosts. The activation of components of the adaptive immune system, including cytotoxic T lymphocytes specific for pathogen- or tumor-derived peptides, is crucial for the establishment of immuno- protection. Hsps acquire these peptides during intracellular protein degradation and when released during necrotic cell death, facilitate their uptake and Minor Histocompatibility Complex (MHC)-restricted representation by professional antigen-presenting cells (APCs). In addition, the interaction of Hsps with APCs, including the Endoplasmatic Reticulum (ER)-resi…
PD-1 signalling in CD4+T cells restrains their clonal expansion to an immunogenic stimulus, but is not critically required for peptide-induced tolera…
2010
Summary The ultimate outcome of T-cell recognition of peptide–major histocompatibility complex (MHC) complexes is determined by the molecular context in which antigen presentation is provided. The paradigm is that, after exposure to peptides presented by steady-state dendritic cells (DCs), inhibitory signals dominate, leading to the deletion and/or functional inactivation of antigen-reactive T cells. This has been utilized in a variety of models providing peptide antigen in soluble form in the absence of adjuvant. A co-inhibitory molecule of considerable current interest is PD-1. Here we show that there is the opportunity for the PD-1/PD-L1 interaction to function in inhibiting the T-cell r…
Tcgfiii/p40 is produced by naive murine cd4+ t cells but is not a general t cell growth factor*
1989
Several antigen-specific T cell lines were found to secrete a lymphokine upon activation by antigen or lectin that was provisionally termed T cell growth factor III (TCGF III) because it induced the proliferation of a CD4+ T cell clone independently from IL2 and IL4. Amino acid sequence analysis (and the functional properties of TCGF III) revealed that TCGF III was identical with a recently identified lymphokine termed P40. TCGF III/P40 was not only produced by long-term cultured T cell lines but also upon stimulation of freshly isolated Mlsa-reactive T cells. In addition, naive CD4+ T cells secreted TCGF III/P40 upon activation by lectin or allo-major histocompatibility complex structures.…