What is the role of T cells in the immune response?

T cells play a pivotal role in the immune response, particularly in identifying and eliminating cells that have been infected by pathogens, such as viruses, or cancerous cells. This function is primarily carried out by a specific type of T cell known as cytotoxic T cells. These cells recognize antigens presented by infected or abnormal cells and initiate a response that leads to the destruction of those cells. By doing so, T cells help control and eliminate infections and contribute to the overall surveillance of the body against tumor cells.

The other options do involve functions relevant to the immune system, but they pertain to different aspects. For instance, the production of antibodies is primarily the role of B cells, not T cells. The enhancement of blood circulation during an infection involves the action of various substances including histamines and not T cells directly. Finally, forming a barrier against physical damage is more aligned with the function of physical barriers such as the skin and mucous membranes, rather than a specific role of T cells. Thus, T cells are essential for their ability to directly target and eliminate compromised cells, making them a critical component in the adaptive immune response.