IV 8 1 T Cell Killing H264

Summary

This video explains the immune response to viral infections, focusing on CD8 T cells and their mechanism of action. It details how viruses infect epithelial cells, hijacking their machinery to produce viral proteins. These proteins are presented on MHC class I molecules, which CD8 T cells recognize, leading to their activation. Upon activation, cytotoxic T cells release perforin and granzymes, inducing apoptosis in infected cells. The process illustrates the intricate interaction between the immune system and viral pathogens, highlighting how T cells effectively eliminate infected cells to maintain health.

Takeaways

• 😀 Viruses are intracellular pathogens that hijack host cell machinery to replicate.
• 😀 Infected cells display viral peptides on MHC class I molecules, which are recognized by CD8 T cells.
• 😀 Activation of CD8 T cells leads to the killing of infected cells to prevent viral spread.
• 😀 T cell receptors and CD8 molecules bind to MHC class I complexes to initiate the cytotoxic response.
• 😀 Cytotoxic T cells contain granules with perforin and granzymes that are essential for cell destruction.
• 😀 Perforin facilitates the entry of granzymes into the target cell's cytosol.
• 😀 Granzymes trigger apoptosis-like cell death by cleaving proteins that regulate cell survival.
• 😀 The cleavage of Bid by granzymes promotes the release of cytochrome c from mitochondria.
• 😀 Granzyme B activates procaspase-3, leading to further cell death through DNA degradation.
• 😀 The mechanism of killing by CD8 T cells is crucial for controlling viral infections and maintaining immune defense.

Q & A

What are viruses and how do they interact with host cells?

Viruses are intracellular pathogens that infect host cells, such as epithelial cells, using the host's biosynthetic machinery to produce new viral proteins.

How are viral proteins displayed on the infected cell surface?

Once inside the cell, viral proteins are degraded, and viral peptides are displayed on the cell surface bound to MHC class I molecules.

What role do CD8 T-cells play in the immune response to viral infection?

CD8 T-cells recognize MHC-peptide complexes, which activates them to kill the infected cells displaying these complexes.

What happens after a CD8 T-cell kills an infected cell?

After killing one infected cell, the CD8 T-cell can migrate to find and kill additional target cells.

What initiates the killing process of infected cells by T-cells?

The killing process is initiated when the T-cell receptor and CD8 bind to an MHC class I molecule presenting a viral peptide, producing activation signals.

What are cytotoxic granules and what do they contain?

Cytotoxic granules are membrane vesicles in T-cells that contain proteins like perforin and granzymes, which are essential for killing target cells.

What is the function of perforin in the killing process?

Perforin facilitates the delivery of granzymes into the cytosol of the target cell, allowing them to induce cell death.

How do granzymes induce apoptosis in target cells?

Granzymes cleave various cellular proteins that regulate apoptosis, such as Bid and procaspase 3, initiating the cell death process.

What is the significance of cytochrome c release in the apoptosis pathway?

The release of cytochrome c from mitochondria into the cytosol activates downstream signaling that leads to DNA degradation and cell death.

What happens to the DNA of the infected cell during apoptosis?

During apoptosis, active DNA migrates into the nucleus and degrades, ensuring the complete death of the infected cell.