Immune surveillance of unhealthy cells by natural killer cells

Area of Science:

• Immunology
• Cell Biology
• Cancer Biology

Background:

• Pathogenic and oncogenic insults trigger intrinsic (cell-death, senescence) and extrinsic (immune response) defense mechanisms.
• Unhealthy cells, including virally infected or malignant cells, are recognized by natural killer (NK) and T cells via the activating receptor NKG2D.
• The NKG2D/ligand system is a key recognition mechanism for identifying and eliminating compromised cells.

Purpose of the Study:

• To discuss pathways responsible for the cell-surface display of NKG2D ligands.
• To review new findings on the recruitment of immune cells for tumor elimination.
• To highlight the cooperative effect of NKG2D ligand induction and immune cell mobilization.

Main Methods:

• Review of pathways inducing NKG2D ligand cell-surface display.
• Discussion of stress pathways involved in ligand presentation.
• Analysis of immune cell recruitment mechanisms, including p53-dependent chemokine production.

Main Results:

• NKG2D ligands are self-proteins minimally expressed on normal cells, but upregulated on unhealthy cells.
• Efficient tumor cell elimination requires NK cell and other immune cell recruitment.
• p53-dependent chemokine production by senescent tumors can regulate immune cell recruitment.

Conclusions:

• The NKG2D/ligand system is a critical component of the immune system's surveillance against cellular damage and transformation.
• Coordinated pathways for NKG2D ligand display and immune cell mobilization enhance the specificity and efficacy of immune responses.
• Understanding these mechanisms offers potential for novel cancer immunotherapies.