CTLA-4 (Cytotoxic T-lymphocyte-associated protein 4), also known as CD152, is an immune inhibitory receptor constitutively expressed on regulatory T cells (Tregs) and upregulated in activated T cells. CTLA-4 plays a critical role in regulating immune responses to tumor antigens and autoantigens. When CTLA-4 expression is upregulated on the surface of T cells, the T cells bind B7 with a higher avidity, and thus outcompete the positive co-stimulatory signal from CD28. In addition, engagement of CTLA-4 by either of its ligands, CD80 (B7-1) or CD86 (B7-2) on an adjacent antigen presenting cell (APC) inhibits CD28 co-stimulation of T cell activation, cell proliferation and cytokine production.
The CTLA-4 Blockade Bioassay reflects the mechanism of action (MOA) of biologics designed to block the interaction of CTLA-4 with its ligands, CD80 and CD86.
Control Ab, Anti-CTLA-4, is a blocking antibody that shows blocking activity of CTLA-4 with its ligands CD80 and CD86. It is intended for use as a control with the CTLA-4 Blockade Bioassay, which can be used to measure the potency and stability of antibodies and other biologics designed to block the CTLA-4/CD80 and CD86 interaction.