What is the fate of activated cytotoxic T-cells during an immune response?

• A. They phagocytose pathogens and present antigens to helper T-cells.
• B. They become memory B-cells for long-term immunity.
• C. They directly kill infected or cancerous cells by inducing apoptosis.
• D. They differentiate into plasma cells that secrete antibodies.

Answer: (C)

Verified step by step guidance

1. Understand the role of cytotoxic T-cells in the immune system: Cytotoxic T-cells (also known as CD8+ T-cells) are specialized immune cells that play a critical role in identifying and eliminating infected or abnormal cells, such as cancerous cells.
2. Clarify the mechanism of action: Cytotoxic T-cells directly kill target cells by inducing apoptosis (programmed cell death). They achieve this by releasing cytotoxic molecules such as perforin and granzymes, which disrupt the integrity of the target cell membrane and activate apoptotic pathways.
3. Differentiate cytotoxic T-cells from other immune cells: Unlike phagocytes (e.g., macrophages) that engulf pathogens or helper T-cells (CD4+ T-cells) that coordinate immune responses, cytotoxic T-cells focus on directly eliminating compromised cells. They do not phagocytose pathogens or present antigens.
4. Address the incorrect options: Cytotoxic T-cells do not differentiate into plasma cells (which secrete antibodies) or memory B-cells (which provide long-term immunity). These functions are specific to B-cells, not T-cells.
5. Conclude the fate of activated cytotoxic T-cells: During an immune response, activated cytotoxic T-cells directly kill infected or cancerous cells by inducing apoptosis, ensuring the removal of harmful cells from the body.