target cell

Examples of target cell in the following topics:

• Forms of Signaling

  • The main difference between the different categories of signaling is the distance that the signal travels through the organism to reach the target cell.
  • Hormones travel the large distances between endocrine cells and their target cells via the bloodstream, which is a relatively slow way to move throughout the body.
  • Because of their form of transport, hormones get diluted and are present in low concentrations when they act on their target cells.
  • This means the signaling cell and the target cell can be the same or a similar cell (the prefix auto- means self, a reminder that the signaling cell sends a signal to itself).
  • In chemical signaling, a cell may target itself (autocrine signaling), a cell connected by gap junctions, a nearby cell (paracrine signaling), or a distant cell (endocrine signaling).

• Natural Killer Cells

  • After a pathogen enters the body, infected cells are identified and destroyed by natural killer (NK) cells, which are a type of lymphocyte that can kill cells infected with viruses or tumor cells (abnormal cells that uncontrollably divide and invade other tissue).
  • As such, NK cells offer a complementary check for unhealthy cells, relative to T cells.
  • After the NK cell detects an infected or tumor cell, its cytoplasm secretes granules comprised of perforin: a destructive protein that creates a pore in the target cell.
  • A granzyme, a protease that digests cellular proteins, induces the target cell to undergo programmed cell death, or apoptosis.
  • Phagocytic cells then digest the cell debris left behind.

• Cancer and Translational Control

  • Both forms appear to be involved in initiating controlled cell death mechanisms in normal cells.
  • However, in colon cancer cells, expression of the long form results in increased cell growth instead of cell death.
  • With an increased understanding of gene regulation and gene function, medicines can be designed to specifically target diseased cells without harming healthy cells.
  • Undoubtedly, more targeted therapies will be developed as scientists learn more about how gene expression changes can cause cancer .
  • Scientists are using knowledge of the regulation of gene expression in individual cancers to develop new ways to treat target diseased cells and prevent the disease from occurring.

• White Blood Cells

  • White blood cells, also called leukocytes, play an important role in the body's immune response by identifying and targeting pathogens.
  • They are primarily involved in the immune response to identify and target pathogens, such as invading bacteria, viruses, and other foreign organisms.
  • They include B cells, T cells, and natural killer cells.
  • T cells attack viruses, fungi, some bacteria, transplanted cells, and cancer cells.
  • One reason that HIV poses significant management challenges is because the virus directly targets T cells by gaining entry through a receptor.

• 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.
  • 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.
  • Only those cells that react weakly to the body's own cells will remain.
  • B cells are involved in the humoral immune response, which targets pathogens loose in blood and lymph, while T cells are involved in the cell-mediated immune response, which targets infected cells.

• Cell Signaling and Cell Death

  • When a cell is damaged, unnecessary, or dangerous to an organism, a cell can initiate the mechanism for cell death known as apoptosis.
  • When a cell is damaged, superfluous, or potentially dangerous to an organism, a cell can initiate a mechanism to trigger programmed cell death, or apoptosis.
  • T-cells are immune cells that bind to foreign macromolecules and particles, targeting them for destruction by the immune system.
  • Normally, T-cells do not target "self" proteins (those of their own organism), a process that can lead to autoimmune diseases.
  • If the T-cell receptor binds to self proteins, the cell initiates apoptosis to remove the potentially dangerous cell.

• Programmed Cell Death

  • Programmed cell death describes the death of a cell through a highly regulated process, and serves many functions in an organism.
  • Programmed cell-death (or PCD) is death of a cell in any form, mediated by an intracellular program.
  • T-cells are immune cells that bind to foreign macromolecules and particles, and target them for destruction by the immune system.
  • Normally, T-cells do not target "self" proteins (those of their own organism), a process that can lead to autoimmune diseases.
  • If the T-cell receptor binds to self proteins, the cell initiates apoptosis to remove the potentially dangerous cell.

• Exocytosis

  • Exocytosis is the process by which cells release particles from within the cell into the extracellular space.
  • Exocytosis is used continuously by plant and animal cells to excrete waste from the cells.
  • In some cells, there is no priming.
  • The final stage, vesicle fusion, involves the merging of the vesicle membrane with the target membrane.
  • The contents are then released to the exterior of the cell.

• Cell Signaling and Cell Growth

  • Cell signaling pathways play a major role in cell division.
  • Cells do not normally divide unless they are stimulated by signals from other cells.
  • Signaling pathways control cell growth.
  • This prevents the cell from regulating its cell cycle, triggering unrestricted cell division and cancer.
  • Cancer biologists realized that gene duplication led to HER2 overexpression in 25 percent of breast cancer patients and developed a drug called Herceptin (trastuzumab), a monoclonal antibody that targets HER2 for removal by the immune system.

• Humoral Immune Response

  • B cells are the major cell type involved in the humoral immune response.
  • In most cases, the sensitized B cell must then encounter a specific kind of T cell, called a helper T cell, before it is activated.
  • This activation of the helper T cell occurs when a dendritic cell presents an antigen on its MHC II molecule, allowing the T cell to recognize it and mature.
  • These daughter cells become either plasma cells or memory B cells.
  • Antibodies may inhibit infection by (a) preventing the antigen from binding its target, (b) tagging a pathogen for destruction by macrophages or neutrophils, or (c) activating the complement cascade.