T-killer cells, also known as cytotoxic CD8 T cells, release specific proteins to eliminate target cells.
The Primary Weaponry of T-Killer Cells
Cytotoxic T-cells are crucial players in the immune system's defense against infected or cancerous cells. They accomplish their task by directly inducing the death of these unwanted cells. According to the provided reference, T-killer cells achieve this by releasing two types of preformed cytotoxic protein:
- Granzymes: These are a family of enzymes capable of inducing apoptosis (programmed cell death) in target cells. The reference notes that granzymes "seem able to induce apoptosis in any type of target cell."
- Perforin: This is a pore-forming protein. Its role is to create channels or "punches holes" in the membrane of the target cell.
These two proteins work in concert. Perforin creates the necessary entry points, allowing the granzymes to pass through the target cell membrane and initiate the process of apoptosis from within.
How the Release Mechanism Works
When a T-killer cell recognizes a target cell (like a virus-infected cell or a cancer cell), it forms a close connection. Once this contact is established, the T-killer cell releases small vesicles containing the preformed perforin and granzymes directly into the space between the two cells, called the immunological synapse.
The perforin then acts quickly to disrupt the target cell's membrane, creating pores. Following this, the granzymes utilize these pores to enter the target cell. Inside, granzymes activate a cascade of enzymes that dismantle the cell's components, leading to its controlled self-destruction via apoptosis.
Summary of Released Proteins:
| Protein | Type | Primary Function |
|---|---|---|
| Granzymes | Cytotoxic Enzyme | Induces apoptosis (programmed cell death) in target cells. |
| Perforin | Pore-Forming Protein | Creates holes in the target cell membrane for granzyme entry. |
This targeted release mechanism ensures that only the specific target cell is affected, minimizing damage to surrounding healthy tissues.
