20 of 60 ONS/ONCC Chemotherapy Immunotherapy Which of the following cells coordinate the immune response and cell-mediated immunity? A. B cells B. T cells C. NK cells D. Dendritic cells
The correct answer and explanation is:
The correct answer is B. T cells.
T cells are a crucial part of the immune system, specifically in cell-mediated immunity, which is responsible for targeting infected or cancerous cells. They originate in the bone marrow but mature in the thymus, where they learn to differentiate between the body’s own cells and foreign invaders. There are different types of T cells, each with specialized functions in immunity.
Helper T cells (CD4+ T cells) coordinate the immune response by releasing cytokines, which are signaling molecules that help activate other immune cells, including B cells and cytotoxic T cells. They also help in the activation of macrophages, which can engulf and destroy pathogens or infected cells. The cytotoxic T cells (CD8+ T cells) play a direct role in killing infected or cancerous cells by recognizing specific antigens on these cells’ surfaces and inducing cell death.
The role of T cells in immunity is highly specialized. For instance, when a virus infects a cell, the infected cell presents viral antigens on its surface. T cells recognize these antigens, and cytotoxic T cells target the infected cell, while helper T cells orchestrate a broader immune response.
In contrast, B cells are primarily involved in humoral immunity, which involves producing antibodies that neutralize pathogens. Natural Killer (NK) cells play a role in innate immunity, killing infected or tumor cells without needing prior sensitization. Dendritic cells act as antigen-presenting cells, bridging the innate and adaptive immune systems by activating T cells.
Thus, T cells are the main players in coordinating cell-mediated immunity, distinguishing them from other immune cells in their function and specialization.