Search results for "killer"
showing 10 items of 286 documents
Chemokines enhance immunity by guiding naive CD8+ T cells to sites of CD4+ T cell-dendritic cell interaction.
2005
CD8+ T cells have a crucial role in resistance to pathogens and can kill malignant cells; however, some critical functions of these lymphocytes depend on helper activity provided by a distinct population of CD4+ T cells. Cooperation between these lymphocyte subsets involves recognition of antigens co-presented by the same dendritic cell, but the frequencies of such antigen-bearing cells early in an infection and of the relevant naive T cells are both low. This suggests that an active mechanism facilitates the necessary cell-cell associations. Here we demonstrate that after immunization but before antigen recognition, naive CD8+ T cells in immunogen-draining lymph nodes upregulate the chemok…
Cooperation of Human Tumor-Reactive CD4+ and CD8+ T Cells after Redirection of Their Specificity by a High-Affinity p53A2.1-Specific TCR
2004
Abstract Efficient immune attack of malignant disease requires the concerted action of both CD8 + CTL and CD4 + Th cells. We used human leukocyte antigen (HLA)-A*0201 (A2.1) transgenic mice, in which the mouse CD8 molecule cannot efficiently interact with the α3 domain of A2.1, to generate a high-affinity, CD8-independent T cell receptor (TCR) specific for a commonly expressed, tumor-associated cytotoxic T lymphocyte (CTL) epitope derived from the human p53 tumor suppressor protein. Retroviral expression of this CD8-independent, p53-specific TCR into human T cells imparted the CD8 + T lymphocytes with broad tumor-specific CTL activity and turned CD4 + T cells into potent tumor-reactive, p53…
Induction of Interleukin 10–Producing, Nonproliferating Cd4+ T Cells with Regulatory Properties by Repetitive Stimulation with Allogeneic Immature Hu…
2000
The functional properties of dendritic cells (DCs) are strictly dependent on their maturational state. To analyze the influence of the maturational state of DCs on priming and differentiation of T cells, immature CD83− and mature CD83+ human DCs were used for stimulation of naive, allogeneic CD4+ T cells. Repetitive stimulation with mature DCs resulted in a strong expansion of alloreactive T cells and the exclusive development of T helper type 1 (Th1) cells. In contrast, after repetitive stimulation with immature DCs the alloreactive T cells showed an irreversibly inhibited proliferation that could not be restored by restimulation with mature DCs or peripheral blood mononuclear cells, or by…
Dendritic Cells Lose Ability to Present Protein Antigen after Stimulating Antigen-Specific T Cell Responses, despite Upregulation of MHC Class II Exp…
2000
Abstract Immature dendritic cells (DC) take up, process and present protein antigens; mature DC are specialized for stimulating primary T cell responses with increased expression of MHC class II and co-stimulatory molecules, but are incapable of processing and presenting soluble protein. The current study examined whether maturation of DC is triggered by T cell recognition of antigens presented by immature DC. Human DC derived from CD34+ progenitor cells by culture with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-6 (IL-6) in serum-free medium could prime naive CD4+ T cells to keyhole limpet hemocyanin (KLH) and ovalbumin (OVA). The cultured DC retained the abil…
Human CD4+CD25+ regulatory T cells and infectious tolerance.
2004
Control of autoaggressive T cells by regulatory T cells (Treg) is essential to ensuring peripheral tolerance. Several subsets of CD(4+) T cells with suppressive properties have been described, including induced T helper (Th) type 3 and T regulatory (Tr) type 1 cells and naturally occurring CD(4+)CD(25+) Treg. CD(4+)CD(25+) Treg suppress the response of conventional T cells in a cell contact-dependent manner, whereas Th3 and Tr1 cells produce immunosuppressive cytokines. Two subsets of human CD(4+)CD(25+) Treg, characterized by expression of the integrins alpha4beta7 or alpha4beta1, are able to convey suppressive capacity to conventional CD(4+) T cells, thereby generating Th suppressor cells…
IL-2 receptor beta-chain signaling controls immunosuppressive CD4+ T cells in the draining lymph nodes and lung during allergic airway inflammation i…
2008
Abstract IL-2 influences both survival and differentiation of CD4+ T effector and regulatory T cells. We studied the effect of i.n. administration of Abs against the α- and the β-chains of the IL-2R in a murine model of allergic asthma. Blockade of the β- but not the α-chain of the IL-2R after allergen challenge led to a significant reduction of airway hyperresponsiveness. Although both treatments led to reduction of lung inflammation, IL-2 signaling, STAT-5 phosphorylation, and Th2-type cytokine production (IL-4 and IL-5) by lung T cells, IL-13 production and CD4+ T cell survival were solely inhibited by the blockade of the IL-2R β-chain. Moreover, local blockade of the common IL-2R/IL-15R…
Quantitative representation of all T cells committed to develop into cytotoxic effector cells and/or interleukin 2 activity-producing helper cells wi…
1984
A limiting dilution culture system based on stimulation with concanavalin A (Con A) has been used to study the quantitative distribution of helper and of cytotoxic precursor cells in Lyt-2-defined subpopulations of murine T cells. Virtually all of the selected Lyt-2+ and Lyt-2-T cells grow and expand to large clonal colonies within an 8-9-day culture period. Our data show that upon stimulation with Con A, 90% of the Lyt-2-T cells were capable to produce interleukin 2 (IL 2) activity. In addition, IL 2 activity is produced by 8-10% of Lyt-2+ T cells. However, at the clonal level, the average of the IL2 activity produced by Lyt-2+ T cells is about 8-fold less as compared to Lyt-2-T cells. Pre…
Interleukin-10–Treated Human Dendritic Cells Induce a Melanoma-Antigen–Specific Anergy in CD8+ T Cells Resulting in a Failure to Lyse Tumor Cells
1999
Abstract Dendritic cells (DC) are critically involved in the initiation of primary immune processes, including tumor rejection. In our study, we investigated the effect of interleukin-10 (IL-10)–treated human DC on the properties of CD8+ T cells that are known to be essential for the destruction of tumor cells. We show that IL-10–pretreatment of DC not only reduces their allostimulatory capacity, but also induces a state of alloantigen-specific anergy in both primed and naive (CD45RA+) CD8+ T cells. To investigate the influence of IL-10–treated DC on melanoma-associated antigen-specific T cells, we generated a tyrosinase-specific CD8+ T-cell line by several rounds of stimulation with the sp…
T helper cell populations: As flexible as the skin?
2011
T helper cells can be defined by the cytokines they produce and are divided into Th1, Th2, Th17, T(FH) or regulatory T cells. Th17 cells have been shown to produce, in addition to IL-17, IL-22. In the current issue of the European Journal of Immunology, an article by Larsen et al. (Eur. J. Immunol. 2011. 41: 2596-2605) provides evidence that human T helper cells, like murine cells, can also express IL-22 in the absence of the other T helper cell signature cytokines. Moreover, they show that these IL-22-producing cells, namely Th22 cells, can be found in the skin of psoriasis patients, where they might contribute to the pathogenesis of this inflammatory skin disease. Finally, they show that,…
T cell directives for transcriptional regulation in asthma.
2003
Allergic asthma frequently starts in childhood, and environmental factors such as viruses, allergens and occupational exposure can regulate the evolution of the disease. The development of allergen-specific Th2 lymphocytes represents the triggering event for the recruitment and activation of IgE-producing B cells and fibroblasts, followed by the release of soluble factors, thus giving rise to the inflammatory reaction observed in this disease. GATA-3 was identified as a cell lineage-specific factor selectively expressed and activated in the Th2 lineage as a consequence of STAT-6 activation. However, recent literature indicates that blockade of CTLA-4-directed inhibitory signals is sufficien…