Search results for "T cell"
showing 10 items of 2228 documents
Tumoricidal Activity of Endothelial Cells
2001
The mechanism of NO- and H(2)O(2)-induced tumor cytotoxicity was examined during B16 melanoma (B16M) adhesion to the hepatic sinusoidal endothelium (HSE) in vitro. We used endothelial nitric-oxide synthetase gene disruption and N(G)-nitro-l-arginine methyl ester-induced inhibition of nitric-oxide synthetase activity to study the effect of HSE-derived NO on B16M cell viability. Extracellular H(2)O(2) was removed by exogenous catalase. H(2)O(2) was not cytotoxic in the absence of NO. However, NO-induced tumor cytotoxicity was increased by H(2)O(2) due to the formation of potent oxidants, likely ( small middle dot)OH and (-)OONO radicals, via a trace metal-dependent process. B16M cells culture…
Murine Model of Cytomegalovirus Latency and Reactivation
2008
Efficient resolution of acute cytopathogenic cytomegalovirus infection through innate and adaptive host immune mechanisms is followed by lifelong maintenance of the viral genome in host tissues in a state of replicative latency, which is interrupted by episodes of virus reactivation for transmission. The establishment of latency is the result of aeons of co-evolution of cytomegaloviruses and their respective host species. Genetic adaptation of a particular cytomegalovirus to its specific host is reflected by private gene families not found in other members of the cytomegalovirus group, whereas basic functions of the viral replicative cycle are encoded by public gene families shared between …
SAT0373 Role of Inkt Cells in Patients with Primary Sjogren Syndrome
2015
Background iNKT cells represent a T cell subset at the bridge between innate and adaptive immunity, playing a role in regulating auto-antibody-producing B cells before their entry into germinal centers. Therefore the absence and/or reduction of iNKT cells seem to increase auto-reactive B cell activation. Primary Sjogren9s syndrome (pSS) is a systemic autoimmune disease in which lymphocyte infiltration and organization in lymphoid structures of inflamed salivary glands occur. Objectives The aim of this study was to investigate the frequency of iNKT in the salivary glands and peripheral blood of patients with pSS and their function by using CD1d/aGalactosylceramide (aGalaCer) tetramers. Metho…
Initiation and Modulation of ECF Generation and Secretion from Human Polymorphonuclear NeutrophilsX.
1978
The primary mediators which are involved in inflammatory processes are histamine, the slow reacting substance of anaphylaxis (SRS-A), the platelet aggregating factor (PAF) and the eosinophil chemotactic factor (ECF). These mediators are primarily localized within mast cells and basophil leucocytes, which represent the target cells of allergic reaction. Binding of IgE to mast cells and basophil leucocytes and addition of the appropriate antigen then leads to the activation of the target cells with a subsequent release of their mediators. SRS and ECF have also been found in a non mast cell source, e.g. in human PMNs. ECF can be generated and released from human PMNs by different stimuli, such…
Cutaneous Leishmania infection: progress in pathogenesis research and experimental therapy.
2007
Studies in murine experimental Leishmania major infection have helped to understand the requirements for efficient development of T helper (Th)1/cytotoxic T (Tc)1-mediated protection against the parasite. As such they have revealed that Fc gamma receptor (Fc gamma R)I and Fc gamma RIII-mediated uptake of L. major amastigotes by dendritic cells (DC) is an important prerequisite for Th1 development. In addition, DC-derived cytokines contribute to adequate T-cell education. DC-based vaccines may thus provide an important tool for both the development of a prophylactic vaccine against leishmaniasis and - together with leishmanicidal drugs - for eliciting immune-deviating functions towards prote…
The CD38-Positive and CD38-Negative Subsets of CD34(high)-Positive Primary Acute Myeloid Leukemia Blasts Differ Considerably in the Expression of Imm…
2008
Abstract Acute myeloid leukemia (AML) is thought to arise from a rare putative ‘leukemic stem cell’ that is capable of self-renewal and formation of leukemic blasts. Serial xenotransplantation studies in immunodeficient mice have shown that this leukemia-initiating cell resides at very low numbers within CD34(high)-positive CD38-negative AML cells. Thus, immunotherapeutic approaches successfully eradicating this cell compartment should result in cure from disease. The objective of our study was to characterize the immune phenotype of the CD38-negative and CD38-positive subsets of primary CD34(high)-positive AML blasts ex vivo. We obtained therapeutic leukapheresis products from 17 AML patie…
EFFECT OF M-LOCUS DEPENDENT T-CELL PROLIFERATION UPON THE INDUCTION OF ANTI H-2 CYTOTOXIC T EFFECTOR CELLS
1975
SUMMARY The influence of M-locus dependent T cell proliferation on the induction of anti H-2 cytotoxic T lymphocytes (CTL) was tested in an in vitro murine cytotoxic allograft model. BALB/c (or CBA/H) derived responder cells (H-2d or H-2k) were cultured together with either C57BL derived fibroblasts or C57BL derived (H-2b), U.V. light irradiated, splenic lymphocytes. These stimulator cells lack functionally active lymphocyte activating determinants (LADs), but display serologically defined (SD) H-2 antigenic specificities. The cytotoxic anti SD-activity obtained was weak. Under certain experimental conditions, the addition of stimulator cells which are H-2 identical to the responder cells b…
Cytotoxicity of fagaramide derivative and canthin-6-one from Zanthoxylum (Rutaceae) species against multidrug resistant leukemia cells
2019
In our continuous search for cytotoxic compounds from the genus Zanthoxylum, chromatographic separation of the MeOH/CH2Cl2 (1:1) extract of Z. chalybeum yielded one new alkamide; 4-(isoprenyloxy)-3-methoxy-3,4-deoxymethylenedioxyfagaramide (1) and a known one; fagaramide (2). Similarly, from the MeOH/CH2Cl2 (1:1) extract of the stem bark of Z. parachanthum four known compounds; canthin-6-one (3), dihydrochelerythrine (4), lupeol (5) and sesamin (6) were isolated. Characterization of the structures of these compounds was achieved using spectroscopic techniques (NMR and MS). Using resazurin reduction assay 1, 3 and 6 displayed moderate cytotoxicity with IC50 values below 50 μM against the dru…
Digitalis spp.: In Vitro Production of Haploids
1990
Digitalis, a member of the Scrophulariaceae, is composed of biennial or perennial herbs and occasionally of small shrubs. Several Digitalis species are used therapeutically, as they are a source of cardiac glycosides. The importance and distribution of these species are summarized below, with special attention to D. purpurea, D. lanata and D. obscura. For a detailed review see Thtin et al. (1972), Morton (1977), and Font Quer (1978).
Antigen dose-dependent suppression of murine IgE responses is mediated by CD4−CD8− double-negative T cells
2010
Background The IgE response against protein antigens is profoundly influenced by the dose used for sensitization. Objective The aim of the study was to identify immune cells that are involved in antigen dose-dependent regulation of IgE formation. Methods Wild-type mice as well as T helper (Th)1-deficient IL-12p40(-/-) and IFN-gamma(-/-) mice were immunized by repeated intraperitoneal injection of either low doses (K01 mice) or high doses (K100 mice) of keyhole limpet haemocyanin adsorbed to aluminium hydroxide. Splenocytes of immunized mice were restimulated in vitro and antigen-dependent T cell proliferation and cytokine production were measured. The frequency of regulatory T cell subsets …