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. Author manuscript; available in PMC: 2015 Oct 1.
Published in final edited form as: Clin Cancer Res. 2014 Jun 26;20(19):4982–4984. doi: 10.1158/1078-0432.CCR-14-0933

Figure 1.

Figure 1

Potential interactions between cancer cells and T cells limited by PD-1/PD-L1. A) Adaptive immune resistance happens when a T cell with a T cell receptor (TCR) specific for a tumor antigen is activated upon antigen recognition on the surface of a cancer cell. Upon activation, the T cell expresses PD-1 and also releases interferons. The interferons are recognized by the cancer cell and lead to the adaptive surface expression of PD-L1. In this case there is a co-localization of T cells, tumor cells and PD-1 and PD-L1. B) In some instances, oncogenic events in the cancer cells lead to constitutive PD-L1 expression, which may be independent of the presence of tumor antigen-specific T cells. C) In other scenarios, T cells may infiltrate cancers in an environment that leads to their inactivation, not triggering the production of interferons and therefore not resulting in the adaptive expression of PD-L1.