Fig. 5
From: The intersection of COVID-19 and cancer: signaling pathways and treatment implications
Immune checkpoint signaling in cancer and coronavirus disease 2019 (COVID-19). Immune checkpoint signaling involves several key steps. T cell receptors (TCRs) recognize their cognate antigens present on major histocompatibility complexes (MHCs) on antigen-presenting cells (APCs) or tumor cells. Several immune checkpoint molecules (such as programmed death (PD)-1) and their respective ligands (such as PD-L1) interact with each other to limit the hyperactivation and duration of the immune response. Immune checkpoint inhibition (ICI) treatment, such as anti-PD-1 antibodies, reactivates the cytotoxic T cell response against cancer and SARS-CoV-2 infection