The Immune System’s Response to Viral Infections: Key Role of Cytotoxic T Cells and NK Cells in Destroying Virus-Infected Cells

Destroys virus-infected cells

When it comes to the immune system’s response to viral infections, one of the key defensive mechanisms is the destruction of virus-infected cells

When it comes to the immune system’s response to viral infections, one of the key defensive mechanisms is the destruction of virus-infected cells. This process is crucial in preventing the spread of the virus to other healthy cells in the body.

Once a virus infects a host cell, it takes over the cell’s machinery to replicate and produce more viral particles. However, infected cells can trigger various immune responses that help combat the infection.

One of the primary immune cells involved in eliminating virus-infected cells are cytotoxic T cells (also known as killer T cells). These specialized white blood cells can recognize infected cells through the presence of viral antigens displayed on the infected cell’s surface. Antigens are proteins or other molecules from the virus that are recognized as foreign by the immune system.

When a cytotoxic T cell identifies an infected cell, it releases specialized proteins called perforins and granzymes. Perforins create pores in the membrane of the infected cell, allowing entry of the granzymes into the cell. Granzymes then initiate a cascade of events within the infected cell, leading to its destruction.

The exact mechanism by which granzymes induce cell death can vary. They can trigger the activation of enzymes called caspases, leading to programmed cell death, or apoptosis. Alternatively, granzymes can directly target and disrupt specific cellular components necessary for cell function, resulting in cell death.

In addition to cytotoxic T cells, natural killer (NK) cells also play a role in eliminating virus-infected cells. NK cells can recognize and kill infected cells without prior exposure to the virus or the need for specific antigen recognition. They achieve this by detecting changes in cell surface molecules known as major histocompatibility complex (MHC) class I molecules, which are downregulated in virus-infected cells.

Once NK cells recognize these changes, they release cytotoxic granules similar to perforins and granzymes that induce cell death in the infected cells. NK cells also secrete substances called cytokines that can further activate other components of the immune response.

The destruction of virus-infected cells is essential for removing the source of viral replication and preventing the spread of infection. Through the coordinated efforts of cytotoxic T cells and NK cells, the immune system can effectively target and eliminate infected cells, thus aiding in the control and resolution of viral infections.

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