Description
CTLA4 or CTLA-4 (cytotoxic T-lymphocyte-associated protein 4), also known as CD152 (cluster of differentiation 152), is a protein receptor that, functioning as an immune checkpoint, downregulates immune responses. CTLA4 is constitutively expressed in regulatory T cells but only upregulated in conventional T cells after activation - a phenomenon which is particularly notable in cancers. It acts as an off switch when bound to CD80 or CD86 on the surface of antigen-presenting cells.
The CTLA-4 protein is encoded by the Ctla4 gene in mice and the CTLA4 gene in humans