Nk cells

Definition

Natural killer (NK) cells are a type of lymphocyte that plays a crucial role in the immune system by providing rapid responses to viral infections and controlling tumor formation. These cells are part of the innate immune response and can recognize and eliminate infected or cancerous cells without prior sensitization. Their activity is influenced by chemokines, which guide their movement to sites of infection or inflammation.

5 Must Know Facts For Your Next Test

1. NK cells can directly kill virus-infected cells and tumor cells through the release of cytotoxic granules containing perforin and granzymes.
2. The activation of NK cells is regulated by a balance between activating receptors and inhibitory receptors that detect stress signals on target cells.
3. Chemokines such as CCL5 (RANTES) and CXCL8 (IL-8) play important roles in attracting NK cells to sites of infection or inflammation.
4. NK cells can also secrete various cytokines, such as IFN-γ, which help enhance the overall immune response and activate other immune cells.
5. The development and maturation of NK cells occur primarily in the bone marrow and are influenced by cytokines such as IL-15.

Review Questions

• How do chemokines influence the function and activity of NK cells during an immune response?
  • Chemokines are critical for guiding NK cells to sites of infection or inflammation. They create a gradient that NK cells can follow to migrate toward affected tissues. For example, chemokines like CCL5 attract NK cells, enhancing their ability to respond quickly to viral infections or tumors. This directed movement ensures that NK cells are present where they are most needed, facilitating a swift immune response.
• Evaluate the role of NK cells in distinguishing between healthy and infected or cancerous cells through receptor interactions.
  • NK cells utilize a combination of activating and inhibitory receptors to evaluate target cells. Activating receptors detect stress ligands upregulated on infected or cancerous cells, while inhibitory receptors recognize normal self-MHC molecules. This balance allows NK cells to selectively eliminate abnormal cells while sparing healthy ones, ensuring effective immune surveillance without damaging healthy tissue.
• Synthesize the relationship between NK cell function, chemokine signaling, and overall immune system coordination in response to infections.
  • NK cell function is intricately linked to chemokine signaling, which directs these lymphocytes to sites of infection. Upon arrival, NK cells exert their cytotoxic effects while also releasing cytokines like IFN-γ that enhance the activity of other immune components, such as macrophages and T cells. This collaboration creates a robust immune response where chemokine signals ensure coordinated action among different cell types, maximizing the efficacy of the innate immune defense against pathogens.

Related terms

Cytokines:

Small proteins released by cells that have a specific effect on the interactions and communications between cells, playing a vital role in the immune response.

Chemokines: A subset of cytokines that specifically induce chemotaxis in nearby responsive cells, helping to direct the movement of immune cells towards sites of infection.

Lymphocytes: A type of white blood cell that is part of the immune system, including T cells, B cells, and NK cells, each playing distinct roles in immune responses.