CD80 Expressed by CD8 + T Cells Contributes to PD-L1-Induced Apoptosis of Activated CD8 + T Cells

Tumor cells are capable of limiting antitumor cd8 + t cell responses through their cell surface expression of pd-l1. in addition to pd-1 expressed by cd8 + t cells,pd-l1 also binds to cd80 expressed by cd8 + t cells. the influence of the pd-l1/cd80 interaction on cd8 + t cell function has not been fully characterized,so we sought to investigate the impact of the pd-l1/cd80 interaction on pd-l1-induced apoptosis of activated cd8 + t cells. we found that cd8 + t cells that lacked cd80 expression got activated to the same extent as wild-type cd8 + t cells,but when cultured with anti-cd3 and pd-l1/fc protein,activated cd8 + t cells that lacked cd80 expression survived better than activated wild-type cd8 + t cells. these findings indicate that pd-l1 induces apoptosis in activated cd8 + t cells in part by signaling through cd80. thus,in the design and implementation of checkpoint blockade therapies that target pd-l1,it is essential that both binding partners for pd-l1,pd-1,and cd80 are considered. © 2017 meagan r. rollins and rachel m. gibbons johnson.