The PD-1 ligands PD-L1 and PD-L2 are commonly expressed on the surface of cells, where they regulate immune system activation. However, the specific role played by each ligand has been unclear. Using site-directed mutagenesis, surface plasmon resonance, and crystallography, Philips et al. explore the distinct features of PD-L2 and identify a specific evolutionary event linked to its appearance. This work provides a deeper understanding of how the immune system adapted to mammalian placental gestation and could be an important consideration in the development of new immune checkpoint therapies.

中文翻译：

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胎盘哺乳动物黎明时的检查站悬崖

PD-1配体PD-L1和PD-L2通常在细胞表面表达，它们调节免疫系统的活化。但是，每个配体的具体作用尚不清楚。使用定点诱变，表面等离振子共振和晶体学，Philips等。探索PD-L2的独特特征，并确定与其外观相关的特定进化事件。这项工作提供了对免疫系统如何适应哺乳动物胎盘妊娠的更深入的了解，并且可能是开发新的免疫检查点疗法的重要考虑因素。