Cytotoxic T Lymphocyte Antigen 4 (CTLA-4)

Cytotoxic T Lymphocyte Antigen 4 (CTLA-4) is a protein found on the surface of certain immune cells called T cells. It helps regulate the immune system by acting as a brake, preventing T cells from overreacting. When T cells recognize a threat like an infection or cancer, CTLA-4 can reduce their activity to avoid damage to healthy tissues. In cancer therapy, drugs called checkpoint inhibitors block CTLA-4, boosting the immune response to better attack tumors. Overall, CTLA-4 is a key molecule that maintains immune balance and prevents excessive immune reactions.