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. Author manuscript; available in PMC: 2012 Aug 20.
Published in final edited form as: Curr Pharm Des. 2011;17(21):2221–2238. doi: 10.2174/138161211796957427

Fig. 4. T cell activation in immunosurveillance.

Fig. 4

(A) Tumor antigens are expressed by antigen-presenting cells (APCs). T cells are activated by the binding of expressed tumor antigens to T cell receptors. The activation requires the binding of CD80/CD86 from APCs to CD28 which is expressed on T cell surface. (B) CTLA-4 is a homolog of CD28 expressed on T cells. CTLA-4 can bind to CD80/CD86 with a high affinity. This binding prevents the activation of T cells even in the presence of tumor antigen on APCs. Blocking the binding between CTLA-4 and CD80/CD86 may resume T cell activation and enhance immunosurveillance.