The PD-1 co-inhibitory pathway is a key regulator of the critical balance between stimulatory and inhibitory signals needed for effective immune responses to microbes and tumors, as well as self-tolerance. This pathway consists of the inhibitory Programmed Death (PD)-1 receptor and its two ligands, PD-L1 (B7-H1; CD274) and PD-L2 (B7-DC; CD273). PD-1 is inducibly expressed on T cells, and its ligands have distinct expression patterns. PD-L1 is broadly expressed on hematopoietic and non-hematopoietic cells, whereas PD-L2 is inducibly expressed primarily on DCs and macrophages. In this talk, mechanisms by which the PD-1:PD-L pathway regulates optimal immune homeostasis and tolerance will be discussed. In addition, the functions of the PD-1 pathway in controlling humoral immune responses will be discussed, and compared to the functions of CTLA-4 in regulating humoral immunity.
Citation Format: Arlene H. Sharpe. Biology of the PD-1 pathway. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr IA02.
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