Natural Killer Cells

Definition

Natural killer (NK) cells are a type of lymphocyte that play a crucial role in the innate immune response. They are part of the body's first line of defense against pathogens and infected or cancerous cells, and their function is closely tied to the production of the formed elements and the barrier defenses of the innate immune system.

5 Must Know Facts For Your Next Test

1. Natural killer cells are able to recognize and kill cells that are infected with viruses or have become cancerous, without the need for prior sensitization.
2. NK cells release cytotoxic granules containing perforin and granzymes, which induce apoptosis (programmed cell death) in target cells.
3. The activity of NK cells is regulated by a balance of activating and inhibitory receptors, which allow them to distinguish between normal, healthy cells and abnormal or infected cells.
4. NK cells play a crucial role in the early immune response by rapidly killing infected or transformed cells, before the adaptive immune system can mount a specific response.
5. The development and maturation of natural killer cells occurs in the bone marrow and is influenced by various cytokines, including interleukin-15 (IL-15).

Review Questions

• Explain the role of natural killer cells in the production of the formed elements of the blood.
  • Natural killer cells are a type of lymphocyte, which are one of the formed elements of the blood. They are produced in the bone marrow and play a key role in the innate immune response by rapidly identifying and destroying infected or cancerous cells. The development and maturation of NK cells is influenced by cytokines produced during the production of the formed elements, such as interleukin-15 (IL-15). As part of the innate immune system, natural killer cells provide an immediate defense against pathogens, complementing the adaptive immune response carried out by other lymphocytes like T cells and B cells.
• Describe how natural killer cells contribute to the barrier defenses and innate immune response.
  • Natural killer cells are a crucial component of the innate immune system's barrier defenses. They are able to recognize and kill cells that have become infected or cancerous, without the need for prior sensitization. This rapid response is facilitated by the balance of activating and inhibitory receptors on NK cells, which allow them to distinguish between normal, healthy cells and abnormal or infected cells. By inducing apoptosis (programmed cell death) in target cells through the release of cytotoxic granules, natural killer cells provide an immediate defense against pathogens and help to prevent the spread of infection or the development of cancer, before the adaptive immune system can mount a specific response.
• Analyze the significance of natural killer cells in the overall immune response and their relationship to the production of the formed elements and the innate immune system.
  • Natural killer cells occupy a unique and critical position within the body's immune defenses. As a type of lymphocyte produced in the bone marrow, they are directly tied to the production of the formed elements of the blood. Their rapid cytotoxic response makes them a key component of the innate immune system's barrier defenses, complementing the more specific adaptive immune response carried out by other lymphocytes like T cells and B cells. By quickly identifying and destroying infected or cancerous cells, natural killer cells play a pivotal role in the body's early immune response, buying time for the adaptive immune system to mount a targeted defense. The development and regulation of NK cells is influenced by various cytokines produced during the production of the formed elements, further highlighting their integral relationship to both the innate and adaptive branches of the immune system.

Related terms

Lymphocytes:

A type of white blood cell that is essential for immune function, including natural killer cells, T cells, and B cells.

Innate Immune System: The body's immediate, non-specific response to pathogens, which includes physical and chemical barriers as well as specialized immune cells like natural killer cells.

Cytotoxicity: The ability of certain cells, such as natural killer cells, to induce the death of target cells through the release of cytotoxic granules.