What type of cells are primarily responsible for the immune response against cancer cells?

Cytotoxic T cells are the primary defenders against cancer cells due to their ability to recognize and directly kill cells that display abnormal proteins on their surfaces, a characteristic often found in cancerous cells. These proteins can arise from mutations, making them foreign to the immune system. Cytotoxic T cells are equipped with specific receptors (T-cell receptors) that can bind to these abnormal proteins presented by Major Histocompatibility Complex (MHC) molecules on the surface of the affected cells.

When a cytotoxic T cell recognizes a cancer cell, it initiates a killing response, which may involve the release of perforins and granzymes that induce apoptosis in the cancerous cell. This targeted immune response is fundamental to controlling the growth and spread of tumors.

While other cell types, such as B cells, helper T cells, and memory cells, play important roles in the immune system—such as antibody production, activating other immune cells, and retaining information about past infections, respectively—it is the cytotoxic T cells that are primarily responsible for directly eliminating cancer cells. This ability highlights their crucial role in immunotherapy approaches aimed at enhancing the body's own defenses against cancer.