OSMT (Ontario Society of Medical Technologists) Practice Exam

Which lymphocyte stimulates activity in antigen encounters?

1. Memory cell

2. Killer T cell

3. Helper T cell

4. Suppressor T cell

The correct answer is: Helper T cell

The Helper T cell is the lymphocyte that plays a crucial role in stimulating activities during antigen encounters. When an antigen is presented to Helper T cells, usually by antigen-presenting cells, they respond by releasing cytokines. These cytokines enhance the activity of other immune cells, including B cells, which produce antibodies, and Killer T cells, which engage in direct cell killing. This coordination is essential for an effective immune response as it amplifies the overall reaction to the antigen, aiding in the elimination of pathogens. In contrast, the other types of lymphocytes have different functions. Memory cells are responsible for long-term immunity, allowing for a faster response upon re-exposure to the same antigen. Killer T cells, also known as cytotoxic T cells, directly attack and destroy infected or cancerous cells. Suppressor T cells help regulate the immune response, preventing excessive reactions that could lead to tissue damage. Each of these cells has a specific role, but Helper T cells are specifically tasked with stimulation and coordination during initial encounters with antigens.