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Anti CTLA-4 Antibodies

How to Choose an Anti-CTLA-4 Antibody for Your Research

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is a co-inhibitory receptor predominantly expressed on T cells. CTLA-4 maintains immune homeostasis during T-cell activation. CTLA-4 signaling results in immunosuppression and restricted T cell function, and its deficiency results in autoimmunity. Through co-stimulation, the activation of T cells depends on the binding of CD28 to its ligands, CD80 (B7-1) and CD86 (B7-2). CTLA-4 preferentially binds to CD80/CD86 and transmits inhibitory signals to prevent CD28-mediated T-cell activation. CTLA-4 is constitutively expressed by regulatory T cells (Tregs), which prevents T cells from killing other cells, including cancer cells. Anti-CTLA-4 antibodies block CTLA-4 binding with CD80 and CD86, and the blockade of CTLA-4 enhances anti-tumor immune responses. The major biological effects and the underlying mechanism of action of CTLA-4-blocking antibodies are illustrated in the figure below:
Explore Bio X Cell Anti-CTLA-4 Antibodies
Biological effects of CTLA-4-blocking antibodies
CTLA-4-blocking antibodies (represented as α-CTLA-4 in the diagram) can promote antibody-dependent cellular cytotoxicity (ADCC), especially when bound to an Fc receptor on an antigen-presenting cell (APC). Because CD4+CD25+ Tregs express higher amounts of CTLA-4 than conventional T cells, they are more prone to anti-CTLA-4 antibody-induced ADCC than conventional T cells. Additionally, anti-CTLA-4 antibodies can bind to CTLA-4 on the surface of the Tregs and prevent it from counter-regulating the CD28-mediated co-stimulatory pathways. Concurrently, anti-CTLA-4 antibodies can also promote T cell responses by blocking CTLA-4 on conventional T cells' surface as they activate. (Source: Waldman et. al., 2020)

References

  1. Krummel MF, Allison JP. CD28 and CTLA-4 have opposing effects on the response of T cells to stimulation. J Exp Med. 1995 Aug 1;182(2):459-65. doi: 10.1084/jem.182.2.459.
  2. Lin CH, Hunig T. Efficient expansion of regulatory T cells in vitro and in vivo with a CD28 superagonist. Eur J Immunol . 2003 Mar;33(3):626-38. doi: 10.1002/eji.200323570.
  3. Linsley P S, Brady W, Urnes M et al. CTLA-4 is a second receptor for the B cell activation antigen B7 J Exp Med . 1991 Sep 1;174(3):561-9. doi: 10.1084/jem.174.3.561.
  4. Quezada SA, Karl S Peggs et al. CTLA-4 blockade and GM-CSF combination immunotherapy alters the intratumor balance of effector and regulatory T cells. J Clin Invest . 2006 Jul;116(7):1935-45. doi: 10.1172/JCI27745. Epub 2006 Jun 15.
  5. Simpson TR, Li F, Montalvo-Ortiz W et. al. Fc-dependent depletion of tumor-infiltrating regulatory T cells co-defines the efficacy of anti-CTLA-4 therapy against melanoma. J Exp Med . 2013 Aug 26;210(9):1695-710. doi: 10.1084/jem.20130579
  6. Waldman AD, Fritz JM, Lenardo MJ. A guide to cancer immunotherapy: from T cell basic science to clinical practice. Nat Rev Immunol. 2020 Nov;20(11):651-668. doi: 10.1038/s41577-020-0306-
  7. Walunas TL, Lenschow DJ, Bakker CY et al. CTLA-4 can function as a negative regulator of T cell activation. Immunity. 1994 Aug;1(5):405-13. doi: 10.1016/1074-7613(94)90071-x.

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