NK Cells

Definition

NK cells, or natural killer cells, are a type of lymphocyte that play a crucial role in the innate immune response against pathogens. They are able to recognize and destroy infected or cancerous cells without prior sensitization, making them an important first line of defense against various threats to the body.

5 Must Know Facts For Your Next Test

1. NK cells are able to recognize and destroy infected or cancerous cells without the need for prior sensitization or antigen presentation.
2. NK cells use a variety of activating and inhibitory receptors to detect and respond to abnormal cells, including the recognition of 'missing self' markers.
3. Upon activation, NK cells release cytotoxic granules containing perforin and granzymes, which induce apoptosis in the target cell.
4. NK cells play a crucial role in the early immune response against viral infections, as they can directly lyse virus-infected cells.
5. Impairment or dysfunction of NK cells has been associated with increased susceptibility to infections, autoimmune disorders, and cancer development.

Review Questions

• Explain the role of NK cells in the innate immune response against pathogens.
  • NK cells are a key component of the innate immune system, providing a rapid and non-specific response to infected or cancerous cells. They are able to recognize and destroy these abnormal cells without the need for prior sensitization or antigen presentation. NK cells use a variety of activating and inhibitory receptors to detect changes in the target cells, such as the expression of 'missing self' markers. Upon activation, NK cells release cytotoxic granules containing perforin and granzymes, which induce apoptosis in the target cell. This allows NK cells to play a crucial role in the early immune response against viral infections, as they can directly lyse virus-infected cells.
• Describe how the function of NK cells differs from that of other lymphocytes, such as T cells and B cells.
  • Unlike T cells and B cells, which are part of the adaptive immune system and require prior exposure to an antigen to mount a specific response, NK cells are part of the innate immune system and do not require prior sensitization. NK cells are able to recognize and respond to infected or cancerous cells immediately, without the need for antigen presentation or clonal expansion. While T cells and B cells rely on the recognition of specific antigens, NK cells use a variety of activating and inhibitory receptors to detect changes in target cells, such as the expression of 'missing self' markers. This allows NK cells to provide a rapid, non-specific response to a wide range of threats, making them a crucial first line of defense against pathogens and abnormal cells.
• Analyze the potential clinical implications of NK cell dysfunction or impairment.
  • Impairment or dysfunction of NK cells has been associated with increased susceptibility to a variety of health issues. Decreased NK cell activity or numbers can lead to a weakened innate immune response, making individuals more vulnerable to viral infections, as NK cells play a crucial role in the early response against viruses by directly lysing infected cells. Additionally, NK cell dysfunction has been linked to the development of autoimmune disorders, as the lack of effective NK cell-mediated clearance of abnormal cells can contribute to the breakdown of self-tolerance. Furthermore, impaired NK cell function has been observed in certain types of cancer, potentially allowing for the evasion of immune surveillance and the proliferation of malignant cells. Understanding the clinical implications of NK cell dysfunction is essential for the development of targeted therapies and interventions aimed at restoring or enhancing NK cell activity to improve patient outcomes.

Related terms

Lymphocytes:

A type of white blood cell that is essential for the adaptive and innate immune response, including T cells, B cells, and NK cells.

Innate Immunity: The body's first, non-specific response to pathogens, involving physical, chemical, and cellular barriers that do not require prior exposure.

Cytotoxicity: The ability of certain cells, such as NK cells, to induce the death of target cells through the release of cytotoxic granules or the activation of apoptotic pathways.