Granzymes

Definition

Granzymes are serine proteases released by cytotoxic T cells and natural killer (NK) cells that play a vital role in the innate immune response. They are involved in inducing apoptosis, or programmed cell death, in target cells, particularly those that are infected or cancerous. By triggering cell death, granzymes help eliminate harmful cells, thus maintaining the integrity of the immune system and supporting overall health.

5 Must Know Facts For Your Next Test

1. Granzymes are released by cytotoxic T cells and natural killer cells as part of the immune response to infection or tumor formation.
2. There are several types of granzymes, with granzyme A and granzyme B being the most well-studied due to their roles in apoptosis induction.
3. Granzymes enter target cells through pores formed by perforin, another protein released by cytotoxic T cells and NK cells.
4. The action of granzymes leads to various cellular responses, including DNA fragmentation, mitochondrial dysfunction, and ultimately, cell death.
5. Deficiencies or malfunctions in granzymes can impair the body's ability to control infections and tumors, highlighting their importance in immune health.

Review Questions

• How do granzymes contribute to the function of cytotoxic T cells and natural killer cells in the immune response?
  • Granzymes are critical for cytotoxic T cells and natural killer cells as they help induce apoptosis in infected or cancerous target cells. Once these immune cells recognize a harmful cell, they release granzymes along with perforin, which creates pores in the target cell's membrane. This allows granzymes to enter the cell and initiate programmed cell death, effectively eliminating the threat and contributing to the overall effectiveness of the innate immune response.
• Discuss the mechanisms through which granzymes induce apoptosis in target cells and their implications for immune function.
  • Granzymes induce apoptosis primarily through the activation of caspases, which are enzymes that play a key role in executing programmed cell death. For example, granzyme B activates caspase-3, leading to DNA fragmentation and cell dismantling. This process not only eliminates infected or cancerous cells but also prevents the spread of pathogens. The ability of granzymes to precisely trigger apoptosis highlights their importance in regulating immune responses and maintaining cellular homeostasis.
• Evaluate the potential consequences of impaired granzyme function on an individual's immune health and susceptibility to diseases.
  • Impaired granzyme function can lead to significant consequences for an individual's immune health. If granzymes are not functioning properly, it may result in insufficient apoptosis of infected or tumor cells, allowing these harmful entities to proliferate unchecked. This could increase susceptibility to chronic infections and cancers, as the body's ability to clear these threats is compromised. Furthermore, research indicates that individuals with defects in granzyme pathways may exhibit increased rates of autoimmune disorders due to failure to regulate immune responses effectively.

Related terms

Cytotoxic T Cells: A subtype of T lymphocytes that directly kill infected or cancerous cells by recognizing specific antigens presented on those cells.

Natural Killer Cells: A type of lymphocyte that plays a crucial role in the innate immune response by recognizing and destroying compromised host cells without prior sensitization.

Apoptosis: A form of programmed cell death that is regulated and plays a crucial role in maintaining cellular homeostasis and immune function.