Answer:
Step-by-step explanation:
Cytotoxic T cells (also known as CD8+ T cells) are a type of white blood cell that play a crucial role in the immune response to viral infections, cancer, and other diseases. These cells are activated when they encounter a specific antigen presented on the surface of an infected or cancerous cell.
The activation of cytotoxic T cells involves several steps. First, an antigen-presenting cell (APC), such as a dendritic cell, engulfs and processes an antigen from a pathogen or cancer cell. The APC then presents the antigen on its surface in combination with major histocompatibility complex (MHC) class I molecules. When a cytotoxic T cell recognizes the specific antigen-MHC complex, it becomes activated and undergoes clonal expansion to produce many copies of itself.
Once activated, cytotoxic T cells can directly kill infected or cancerous cells by releasing toxic molecules such as perforin and granzyme, which create holes in the target cell's membrane and trigger apoptosis (cell death). Additionally, cytotoxic T cells can release cytokines, such as interferon gamma, that help to recruit and activate other immune cells, including macrophages and natural killer cells.
The effects of cytotoxic T cells on the immune system are primarily beneficial, as they help to eliminate cells that are infected with a virus or have become cancerous. This can help to prevent the spread of infection and the development of tumors. However, in some cases, cytotoxic T cells may also attack healthy cells, leading to autoimmune disorders or tissue damage. To prevent this, the immune system employs various mechanisms to regulate the activity of cytotoxic T cells and maintain self-tolerance.