Examples of T cells in the following topics:
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- T cells play a central role in cell-mediated immune response through the use of the surface T cell receptor to recognize peptide antigens.
- Cellular immunity is mediated by T lymphocytes, also called T cells.
- T cells do not produce antibody molecules.
- Effector cells include helper T cells, and cytolytic or cytotoxic T cells.
- Another class of T cells called regulatory T cells function to inhibit immune response and resolve inflammation.
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- The T Cell Receptor (TCR) found on the surface of T cells is responsible for recognizing antigens.
- The receptor that recognizes these peptide-MHC complexes is called the T Cell Receptor (TCR).
- Clones of T cells with different specificities express different TCRs.
- The antigen receptor of MHC-restricted CD4 helper T cells and CD8 cytolytic T cell is a heterodimer consisting of two transmembrane polypeptide chains, designated alpha and beta, covalently linked to each other by disulfide bonds.
- T cell receptor consists of alpha and beta chains, a transmembrane domain, and a cytoplasmic region.
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- Regulatory T cells are a subset of T cells which modulate the immune system and keep immune reactions in check.
- These cells are also called CD4+CD25+ regulatory T cells, or Tregs.
- CD4+Foxp3+ regulatory T cells have been called "naturally-occurring" regulatory T cells, to distinguish them from "suppressor" T cell populations that are generated in vitro.
- Additional suppressor T cell populations include Tr1, Th3, CD8+CD28-, and Qa-1 restricted T cells.
- An additional regulatory T cell subset, induced regulatory T cells, are also needed for tolerance and suppression.
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- Dendritic cells are immune cells that function to process antigens and present them to T cells.
- Mature dendritic cells reside in the T cell zones of the lymph nodes, and in this location they display antigens to T cells.
- Different subpopulations of dendritic cells may stimulate distinct types of T cell effector responses.
- Some may even inhibit T cell activation.
- IL-12 is a signal that helps differentiate naive CD4 T cells into a helper T cell phenotype.
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- Methods used to differentiate T cells and B cells include staining cell surface receptors and functional assays like the T lymphocyte cytotoxicity assay.
- T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes.
- They are called T cells because they mature in the thymus.
- T-lymphocytes can be distinguished from other lymphocytes like B cells and natural killer cells (NK cells) by the presence of a T cell receptor (TCR) on the cell surface.
- Describe how T cells and B cells can be differentiated using staining of cell surface receptors and functional assays like the T lymphocyte cytotoxicity assay
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- This requirement of a T cell can be bypassed in rare instances, such as infection by organisms producing super-antigens, which are capable of initiating polyclonal activation of B cells, or even of T cells, by directly binding to the β-subunit of T cell receptors in a non-specific fashion.
- A normal immune response is assumed to involve B and T cell responses to the same antigen, where B cells recognize conformations on the surface of a molecule for B cells, and T cells recognize pre-processed peptide fragments of proteins for T cells.
- Together with the concept of T cell-B cell discordance, this idea forms the basis of the hypothesis of self-perpetuating autoreactive B cells.
- DQ isoforms can bind to and present foreign and self antigens to T-cells.
- In this process T-cells are stimulated to grow and can signal B-cells to produce antibodies.
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- Central tolerance is the mechanism by which newly developing T cells and B cells are rendered non-reactive to self.
- Regulatory T cells can be considered both central tolerance and peripheral tolerance mechanisms, as they can be generated from self (or foreign)-reactive T cells in the thymus during T cell differentiation.
- However, they exert their immune suppression in the periphery on other self (or foreign)-reactive T cells.
- Positive selection ensures maturation of T cells whose receptors bind weakly to self major histocompatibility complex molecules.
- Both developing B cells and T cells are subject to negative selection during a short period after antigen receptors are expressed.
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- B cells and T cells are the major types of lymphocytes.
- Mammalian stem cells differentiate into several kinds of blood cell within the bone marrow.
- B cells mature into B lymphocytes in the bone marrow, while T cells migrate to, and mature in, a distinct organ called the thymus.
- B and T cells) differentiate further after exposure to an antigen; they form effector and memory lymphocytes.
- Effector lymphocytes function to eliminate the antigen, either by releasing antibodies (in the case of B cells), cytotoxic granules (cytotoxic T cells) or by signaling to other cells of the immune system (helper T cells).
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- CD4 cells or helper T cells provide protection against different pathogens.
- Cytotoxic T cells cause death by apoptosis without using cytokines.
- CD4+ helper T cells recognize antigen in a complex with Class 2 major histocompatibility complex.
- CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Th1 cytokines, thus mediating the immune response.
- Activated CD8+ T cells destroy target cells on contact, whereas activated macrophages produce hydrolytic enzymes and, on presentation with certain intracellular pathogens, transform into multinucleated giant cells.
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- The role NK cells play is similar to that of cytotoxic T cells in the vertebrate adaptive immune response.
- NK cells differ from Natural Killer T cells (NKT) phenotypically, by origin, and by respective effector functions.
- In contrast to NKT cells, NK cells do not express T-cell antigen receptors (TCR) or Pan T marker CD3 or surface immunoglobulins (Ig) B cell receptors, but they usually express the surface markers CD16 (FcγRIII) and CD56 in humans, NK1.1 or NK1.2 in C57BL/6 mice.
- Schematic diagram indicating the complementary activities of cytotoxic T-cells and NK cells.
- Schematic diagram indicating the complementary activities of cytotoxic T-cells and NK cells.