T cell

(noun)

a lymphocyte, from the thymus, that can recognize specific antigens and can activate or deactivate other immune cells

Related Terms

Examples of T cell in the following topics:

  • Classes of T Cells

    • 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.

  • Specific T-Cell Roles

    • T helper cells assist the maturation of B cells and memory B cells while activating cytotoxic T cells and macrophages.
    • Differentiation into helper T cell subtypes occurs during clonal selection following T cell activation of naive T cells.
    • Memory T cells comprise two subtypes: central memory T cells (TCM cells) and effector memory T cells (TEM cells), which have different properties and release different cytokines.
    • Regulatory T cells (Treg cells), also known as suppressor T cells, are crucial for the maintenance of immunological tolerance.
    • T cells become activated upon encountering a pathogen and can become either cytoxic T or helper T cells.

  • Maturation of T Cells

    • T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in the cell-mediated branch of the adaptive immune system.
    • T cells can be either helper T cells or cytoxic T cells based on whether they express CD4 (helper) or CD8 (cytotoxic) glycoprotein.
    • Immature T cells that migrate to the thymus are called thymocytes.
    • This process insures that the T cell receptors on matured T cells will perform their function in the body, because T cells with non functional receptors will not be able to receive antigens, and will be useless to the immune system.
    • The remaining cells exit the thymus as mature naive T cells.

  • Regulatory T Cells

    • 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.

  • Lymphocytes

    • T cells are called T cells because they mature in the thymus.
    • T cells contain T cell receptors (TCRs), which allow them to bind to antigens on MHC complexes.
    • The main categories of T cells are:
    • Subtype 2 helper T cells present antigens to B cells.
    • Suppressor T cells (T-reg cells)- T cells that kept some of their ability to bind to self-cells.

  • Antigen-presenting Cells: B and T cells

    • Whether an immature lymphocyte becomes a B cell or T cell depends on where in the body it matures.
    • The B cells remain in the bone marrow to mature (hence the name "B" for "bone marrow"), while T cells migrate to the thymus, where they mature (hence the name "T" for "thymus").
    • Meanwhile, T cell receptors are responsible for the recognition of pathogenic antigens by T cells .
    • Unlike B cells, T cells do not directly recognize antigens.
    • Explain the role played by B and T cells in the adaptive immune system

  • Antigen-Presenting Cells

    • Antigen presentation is a process where immune cells capture antigens and then enable their recognition by T-cells.
    • Some cells, however, are specially equipped to acquire and present antigen, and prime naive T cells.
    • Antigen presentation stimulates T cells to become either "cytotoxic" CD8+ cells or "helper" CD4+ cells.
    • MHC Class I molecules present antigen to CD8+ cytotoxic T cells.
    • Cytotoxic T cells (also known as TC, killer T cell, or cytotoxic T-lymphocyte (CTL)) are a population of T cells that are specialized for inducing the death of other cells.

  • Dendritic Cells

    • 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.

  • Tests That Differentiate Between T Cells and B cells

    • 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

  • Lymphoid Cells

    • The three major types of lymphocyte are T cells, B cells, and natural killer cells.
    • T cells are involved in cell-mediated immunity whereas B cells are primarily responsible for humoral immunity.
    • There are two types of T-cells involved in adaptive, cell-mediated immunity.
    • Helper T-cells (CD4s)- facilitate the organization of immune responses.
    • Cytotoxic T-cells (CD8s)- destroy pathogens associated with an antigen.