CTLA-4 (Cytotoxic T-Lymphocyte Antigen 4)

CTLA-4 (Cytotoxic T-Lymphocyte Antigen 4) is a protein found on immune cells called T cells. It acts as a checkpoint that helps regulate the immune response by dampening T cell activity, preventing excessive inflammation or attack on healthy cells. When T cells become activated to fight threats like infections or cancer, CTLA-4 serves as a brake to keep the response controlled. In cancer therapy, drugs called checkpoint inhibitors block CTLA-4, boosting the immune system's ability to attack tumors. Overall, CTLA-4 helps maintain immune balance and prevent autoimmune damage.