A Level Biology Practice Exam

Which type of T cell is crucial for the initial activation of the immune response?

1. T killer cells

2. T helper cells

3. T memory cells

4. T regulator cells

The correct answer is: T helper cells

T helper cells play a pivotal role in initiating the immune response by acting as a communication hub within the immune system. They are essential for the activation of other immune cells, including B cells and T killer cells. Once the T helper cells recognize antigens presented by antigen-presenting cells (APCs), they release cytokines that stimulate the immune response. This cytokine signaling amplifies the activity of the immune system, thereby ensuring a robust defense against pathogens. While T killer cells are involved in destroying infected cells, T memory cells are responsible for providing long-term immunity by recalling past infections, and T regulator cells help in maintaining immune tolerance and preventing excessive immune responses, they do not initiate the immune response. This distinctive function of T helper cells highlights their critical role in the overall immune response, making them indispensable for the activation of the immune system.