Multiple Choice
_____ function in humoral immunity, while _____ function in cell-mediated immunity.
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41. Immune System
Immune System
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Which of the following molecules is secreted by cytotoxic T cells and directly involved in the killing of target cells?
A
Perforin
B
Interleukin-2
C
Histamine
D
Antibodies
Verified step by step guidance1
Understand the role of cytotoxic T cells: Cytotoxic T cells (also known as CD8+ T cells) are a type of immune cell that directly kills infected or abnormal cells, such as virus-infected cells or cancer cells. They achieve this by releasing specific molecules that induce cell death in their targets.
Review the function of perforin: Perforin is a protein secreted by cytotoxic T cells. It forms pores in the membrane of the target cell, allowing other molecules, such as granzymes, to enter and trigger apoptosis (programmed cell death).
Eliminate incorrect options: Interleukin-2 is a signaling molecule (cytokine) that helps activate and proliferate T cells but does not directly kill target cells. Histamine is involved in allergic responses and inflammation, not in cytotoxic T cell activity. Antibodies are produced by B cells and are not secreted by cytotoxic T cells.
Identify the correct molecule: Based on the function of perforin and the roles of the other molecules, perforin is the molecule directly involved in the killing of target cells by cytotoxic T cells.
Conclude: The correct answer is perforin, as it is the molecule secreted by cytotoxic T cells that directly contributes to the destruction of target cells by forming pores in their membranes.
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