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. Author manuscript; available in PMC: 2021 Oct 1.
Published in final edited form as: Expert Rev Clin Pharmacol. 2020 Sep 11;13(10):1147–1158. doi: 10.1080/17512433.2020.1817737

Figure 1 – Schematic overview of T cell engagement with tumor cells or antigen presenting cells.

Figure 1 –

Tumor cells and antigen presenting cells (APCs) express a transmembrane major histocompatibility complex (MHC) on their surface. T cell receptors (TCRs) on the surface of T cells are capable of recognize MHC bound to target peptide antigen leading to subsequent T cell activation. Secondary signals via PD-L1 to PD-1 binding and B7 to CD28 or B7 to CTLA-4 serve to modulate the T cell response to APCs or tumor cells expressing target antigen. Checkpoint inhibitors including anti-PD-1 and anti-CTLA-4 have been designed to augment the immune response. Please see accompanying text for further details.