Which T cell type specifically acts to kill tumor cells and virally infected cells?

Cytotoxic T cells are specifically designed to target and eliminate tumor cells and cells infected by viruses. They accomplish this by recognizing abnormal antigens presented on the surface of these compromised cells through their T-cell receptors. Upon recognition, cytotoxic T cells release cytotoxic granules containing perforin and granzymes, which induce apoptosis (programmed cell death) in the infected or malignant cells.

This mechanism is crucial for the immune response, as it allows the body to effectively control and eliminate cells that are harmful due to infection or malignancy. In contrast, helper T cells do not have the capability to directly kill cells; instead, they assist in activating other immune cells. Regulatory T cells play a role in maintaining immune tolerance and preventing autoimmune responses rather than attacking infected or tumor cells. B cells primarily produce antibodies and are mainly involved in humoral immunity, rather than directly killing cells. Therefore, cytotoxic T cells are the appropriate type for this role in the immune system.