Yes, cell mediated immunity is indeed active, especially in response to certain pathogens and immune challenges. It involves the activation of T-cells, which play a crucial role in identifying and eliminating infected or abnormal cells, such as those that have been compromised by a virus or transformed into cancerous cells.
When the body detects an infection, antigen-presenting cells (APCs) process and present pieces of the pathogens to T-cells, specifically helper T-cells. These T-cells then activate cytotoxic T-cells, which are responsible for directly attacking and destroying infected cells.
This process highlights the active nature of cell mediated immunity as it requires a series of steps involving recognition, activation, and response to specific antigens. In addition to combating viral infections and cancer, cell mediated immunity is also involved in the rejection of transplanted tissues. Overall, it’s a dynamic and vital component of the immune system that responds actively to various threats.