cytotoxic

Examples of cytotoxic in the following topics:

• Natural Killer Cells

  • Natural Killer (NK) cells are cytotoxic lymphocytes critical for the innate immune system.
  • Natural killer cells (NK cells) are cytotoxic lymphocyte critical to the innate immune system.
  • The role of NK cells is similar to that of cytotoxic T cells in the adaptive immune response.
  • To control their cytotoxic activity, NK cells possess two types of surface receptors: activating receptors and inhibitory receptors.
  • Schematic diagram indicating the complementary activities of cytotoxic T-cells and NK cells.

• Specific T-Cell Roles

  • T helper cells assist the maturation of B cells and memory B cells while activating cytotoxic T cells and macrophages.
  • Their primary functions include antigen presentation and activation of B cells, and activation of cytotoxic T cells and macrophages.
  • Cytotoxic T cells recognize their antigen on pathogens through their T cell receptor, and will kill the pathogen through degranulation and cell-mediated apoptosis.
  • The cytotoxic enzymes and proteases travel to their target cell through a microtubule cytoskeleton.
  • Effector memory cells may be either CD4+ or CD8+, and will produce either helper or cytotoxic T cells in a secondary immune response.

• Types of Adaptive Immunity

  • Cell mediated immunity is controlled by type 1 helper T-cells (Th1) and cytotoxic T-cells.
  • Helper-T cells facilitate the immune response by guiding cytotoxic T-cells to pathogens or pathogen-infected cells, while the cytotoxic T-cells will kill the pathogens or pathogen-infected cells.
  • Some of the ways in which cytotoxic T-cells kill pathogens include the release of granules that contain the cytotoxins perforin and granzyme, which lyse small pores in the membrane of a pathogen.
  • Helper-T cells will secrete cytokines, such as interferon-gamma, which can activate cytotoxic T-cells and macrophages.

• Overview of Adaptive Immunity

  • The antigen is presented to immature helper T cells and cytotoxic T cells through binding the MHC II (helper T) or MHC I (cytotoxic T) to T-cell receptors.
  • Helper T cells activate B cells, which proliferate and produce antibodies specific to the antigen, while cytotoxic T cells destroy pathogens that bear the antigen that was presented to them by the APCs.
  • Antigen presentation stimulates T cells to become either "cytotoxic" CD8+ cells or "helper" CD4+ cells.
  • Cytotoxic cells directly attack other cells carrying certain foreign or abnormal molecules on their surfaces.

• Antigen-Presenting 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.

• WBC Function

  • When pathogens are encountered, granule dependent apoptosis (a mechanism of cytotoxicity) may be induced in the pathogen by releasing perforins, granzymes, and proteaseases from their granules.
  • Pathogens that bear the T cell's antigen are destroyed through cytotoxic induced apoptosis and protease activity.

• Lymphoid Cells

  • Activated NK cells release cytotoxic (cell-killing) granules that contain perforin and granzyme, which can lyse cell membranes and induce apoptosis to kill infected or abnormal cells.
  • They present antigens to B cells, produce cytokines that guide cytotoxic T cells, and activate macrophages.
  • Cytotoxic T-cells (CD8s)- destroy pathogens associated with an antigen.

• Antigens and Antigen Receptors

  • Cytokines are substances that can activate cytotoxic T lymphocytes (CTL), antibody-secreting B cells, macrophages, and other particles.
  • If activated cytotoxic CD8+ T cells recognize them, the T cells begin to secrete various toxins that cause the lysis or apoptosis of the infected cell.
  • In order to keep the cytotoxic cells from killing cells just for presenting self-proteins, self-reactive T cells are deleted from the repertoire as a result of tolerance (also known as negative selection).

• Maturation of T Cells

  • T cells can be either helper T cells or cytoxic T cells based on whether they express CD4 (helper) or CD8 (cytotoxic) glycoprotein.
  • A thymocyte's differentiation into helper or cytotoxic versions is also determined during positive selection.
  • Double-positive cells (CD4+/CD8+) that are positively selected on MHC class II molecules will eventually become CD4+ helper T cells, while cells positively selected on MHC class I molecules mature into CD8+ cytotoxic T cells.

• Aging and the Immune System

  • The cytotoxicity of Natural Killer (NK) cells and the antigen-presenting function of dendritic cells is known to diminish with old age.
  • hampered immune defences against viral pathogens, especially by cytotoxic CD8+ T cells