CTLA-4

biology

Also known as: cytotoxic lymphocyte associated antigen 4

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July 21, 2026

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CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) is a protein that acts as an immune checkpoint, essentially a brake on the immune system. It plays a crucial role in peripheral immune tolerance, helping to prevent the immune system from attacking the body's own tissues.12

CTLA-4 limits the activity of T-cells, which are a type of white blood cell that plays a central role in the immune response. Cancer cells can exploit CTLA-4 to evade detection by the immune system. Understanding CTLA-4 has led to the development of immune checkpoint inhibitors, a type of cancer therapy that aims to release the brakes on T-cells, allowing them to attack cancer more effectively.31

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antibody
Antibodies in medicine and research
…lymphocyte associated antigen 4 (CTLA4). CTLA4 normally is a powerful inhibitor of T cells. Thus, by releasing the inhibitory signal, ipilimumab augments the immune response, making tumour destruction possible. Similar effects have been achieved with inhibitors of programmed cell death 1 (PD-1), a protein expressed on the surface of…
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…lymphocyte associated antigen 4 (CTLA4). CTLA4 normally is a powerful inhibitor of T cells. Thus, by releasing the inhibitory signal, ipilimumab augments the immune response, making tumour destruction possible. Similar effects have been achieved with inhibitors of programmed cell death 1 (PD-1), a protein expressed on the surface of…
Read More

immune system
Immunity against cancer
…that a molecule known as CTLA-4 plays a role in downregulating immune responses against tumors led to the development of a therapeutic human monoclonal antibody against CTLA-4. Known as ipilimumab (Yervoy), the antibody was approved in 2011 by the U.S. Food and Drug Administration for the treatment of late-stage melanoma.…
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…that a molecule known as CTLA-4 plays a role in downregulating immune responses against tumors led to the development of a therapeutic human monoclonal antibody against CTLA-4. Known as ipilimumab (Yervoy), the antibody was approved in 2011 by the U.S. Food and Drug Administration for the treatment of late-stage melanoma.…
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James P. Allison
…that a molecule known as CTLA-4 opposed CD28 and played a critical role in the downregulation of immune responses. When injected into tumours in mice, CTLA-4 antibody, designed to block CTLA-4 activity, enhanced T-cell responses and led to tumour shrinkage. This approach to boosting immune responses subsequently became known as…
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…that a molecule known as CTLA-4 opposed CD28 and played a critical role in the downregulation of immune responses. When injected into tumours in mice, CTLA-4 antibody, designed to block CTLA-4 activity, enhanced T-cell responses and led to tumour shrinkage. This approach to boosting immune responses subsequently became known as…
Read More