T cell activation by antigen-presenting cell (APC) requires co-stimulatory signaling.1

  • Binding of the CD28 receptor to ligands CD80 or 86 on an antigen-presenting cell (APC) provides a co-stimulatory signal requisite for T cell activation and the consequent inflammatory cascade.1 This interaction is followed by T cell expression of cytotoxic T-lymphocyte–associated antigen-4 (CTLA-4).2
  • In the normal immune response, CTLA-4 competes for CD28 binding to CD80/86. CTLA-4 has a higher binding affinity for CD80/86 and its binding blocks T cell activation by CD28.2
  • In addition, CTLA-4 binding delivers a negative signal that downregulates T cell function and inhibits the excessive expansion of activated T cells.2

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  1. Suchard SJ, Davis PM, Kansal S, et al. J Immunol. 2013;191:4599-4610.
  2. Vasaturo A, Di Blasio S, Peeters DGA, et al. Frontiers Immunol. 2013;4:417.