Which cells play a significant role in graft rejection?

Cytotoxic T cells are crucial in the process of graft rejection because they are specifically tasked with identifying and destroying foreign cells that the body recognizes as non-self. When a transplant occurs, the immune system detects the donor's cells as foreign due to differences in antigens, which are markers present on cell surfaces. Cytotoxic T cells have the capability to recognize these foreign antigens and initiate a response that leads to the destruction of the transplanted tissues.

In addition to their direct action, cytotoxic T cells play an essential role in the overall adaptive immune response by orchestrating responses against the graft. They are equipped with mechanisms to induce apoptosis in target cells, which is integral in rejecting transplanted organs or tissues.

Other cells like B cells, helper T cells, and memory T cells have roles in the immune response, but cytotoxic T cells are the primary effector cells responsible for the direct attack on graft tissues during rejection. While B cells produce antibodies that can contribute to the rejection process, and helper T cells assist in activating various immune responses, it is the cytotoxic T cells that directly mediate the rejection of the graft. Memory T cells are important for long-term immunity but do not initiate rejection during the first exposure to the transplanted tissue