Natural killer (NK) cells

Definition

Natural Killer (NK) cells are a type of lymphocyte that play a crucial role in the innate immune system. They are capable of recognizing and destroying infected or cancerous cells without prior sensitization to antigens.

5 Must Know Facts For Your Next Test

1. NK cells can kill target cells through the release of perforins and granzymes, leading to apoptosis.
2. They recognize stressed cells in the absence of antibodies and MHC, allowing for a faster immune response.
3. NK cell activity is regulated by a balance between activating and inhibitory receptors on their surface.
4. They play a role in both the innate and adaptive immune responses by interacting with other immune cells.
5. Cytotoxicity of NK cells is enhanced by cytokines such as IL-2, IL-12, and IFN-γ.

Review Questions

• How do NK cells identify and destroy target cells?
• What distinguishes NK cell recognition from that of T-cells?
• Which cytokines enhance NK cell cytotoxicity?

Related terms

Major Histocompatibility Complex (MHC):

A set of cell surface proteins essential for acquired immune system to recognize foreign molecules.

Antigen-Presenting Cells (APCs):

Cells that process antigens and present them on their surface to T-cells.

Perforin:

A protein released by NK cells that creates pores in the membrane of target cells leading to apoptosis.