Lymphocytes have two primary functions: antibody production and direct cell-mediated killing of infected and tumor cells. These functions are crucial for a healthy immune response.
Detailed Explanation of Lymphocyte Functions
Lymphocytes are a type of white blood cell integral to the immune system. They come in different forms (T cells, B cells, and natural killer cells) each contributing to the overall immune response.
1. Antibody Production
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B lymphocytes (B cells) are the primary producers of antibodies. When a B cell encounters a foreign substance (antigen), it differentiates into plasma cells that mass-produce antibodies. These antibodies specifically target the antigen, neutralizing it or marking it for destruction by other immune cells. This is known as humoral immunity.
- Example: Antibodies targeting a virus prevent the virus from infecting cells.
2. Direct Cell-Mediated Killing
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T lymphocytes (T cells) and natural killer (NK) cells are responsible for direct cell-mediated killing. T cells, particularly cytotoxic T lymphocytes (CTLs), recognize and destroy virus-infected cells, cancer cells, or other abnormal cells. NK cells kill cells without prior sensitization. This process is known as cell-mediated immunity.
- Example: CTLs identify and kill cancer cells that display abnormal proteins on their surface.
Additional Lymphocyte Functions: Regulation
While the question asks for two functions, it's important to note that lymphocytes also play a critical role in regulating the immune response. This includes controlling the intensity and duration of immune reactions, preventing autoimmune responses, and maintaining immune homeostasis. This regulatory function is partly handled by specific subsets of T cells (helper T cells and regulatory T cells). These cells coordinate the activities of other immune cells.
Reference Integration: The provided references confirm that lymphocytes are responsible for antibody production, and the direct cell-mediated killing of infected and tumor cells. They also highlight the diverse roles of lymphocytes in regulating the immune response and maintaining immune homeostasis (e.g., regulation of the immune response from reference 1, B cells initiating T-cell responses in reference 6, and the role of LAG-3 in regulating T cells in reference 7).
