Biotin Mouse Anti-Mouse CTLA-4 (CD152) Antibody (9D9)

CTLA-4 (cytotoxic T-lymphocyte-associated protein 4, CD152) is an immune checkpoint molecule primarily expressed on the surface of activated T cells and regulatory T cells (Tregs). It belongs to the immunoglobulin superfamily and shares high structural homology with the T-cell costimulatory receptor CD28. Functionally, CTLA-4 binds to B7 molecules (CD80/CD86) on the surface of antigen-presenting cells and competes with CD28 for these ligands with higher affinity, thereby inhibiting T-cell activation, proliferation, and cytokine secretion. This serves as a "brake" on immune responses and is critical for maintaining self-tolerance and preventing excessive inflammatory reactions. In the tumor microenvironment, cancer cells often exploit the CTLA-4 pathway by upregulating its expression to suppress anti-tumor immune responses, achieving immune evasion. Consequently, CTLA-4 has become a major target in cancer immunotherapy, and its blocking agents (e.g., ipilimumab) can relieve T-cell inhibitory signals and reactivate the immune system to attack tumor cells. However, inhibiting the CTLA-4 pathway may also disrupt immune homeostasis, leading to immune-related adverse events (irAEs) such as colitis, dermatitis, and endocrinopathies, thus requiring close monitoring in clinical practice. Additionally, CTLA-4 gene polymorphisms are closely associated with susceptibility to various autoimmune diseases, including rheumatoid arthritis and type 1 diabetes.