Department of Immunology, Medical College of Soochow University, and Clinical Immunology Lab, the First Affiliated Hospital of Soochow University, Suzhou, PR China.
Cytokine. 2011 Nov;56(2):231-8. doi: 10.1016/j.cyto.2011.06.004. Epub 2011 Jul 5.
PD-L1 (CD274) is a critical membrane-bound costimulatory molecule that inhibits immune responses through its receptor, PD-1. Previous data have showed that this molecule is associated with autoimmune diseases, chronic viral infections and tumor immune escape. However, the existence and role of soluble form of human PD-L1 (sPD-L1) remain unknown. We show here that a novel enzyme-linked immunosorbent assay (ELISA) was developed to detect the sPD-L1 protein. Many culture supernatants of the PD-L1+ cell lines contain high levels of this factor. Interestingly, the sPD-L1 is detectable in human serum and the concentration increases in an age-dependent manner. Human sPD-L1 has a unique protein form in the serum and the matrix metalloproteinase inhibitor (MMPI) could suppress sPD-L1 production. Moreover, the sPD-L1 could specially bind to PD-1. Together, these data demonstrate that the existence of circulating sPD-L1 in human serum might play an important role in immunoregulation.
程序性死亡配体 1（CD274）是一种关键的膜结合共刺激分子，通过其受体 PD-1 抑制免疫反应。先前的数据表明，该分子与自身免疫性疾病、慢性病毒感染和肿瘤免疫逃逸有关。然而，人源可溶性程序性死亡配体 1（sPD-L1）的存在和作用尚不清楚。我们在此展示了一种新的酶联免疫吸附测定（ELISA）的开发，用于检测 sPD-L1 蛋白。许多 PD-L1+细胞系的培养上清液中含有高水平的这种因子。有趣的是，sPD-L1 可在人血清中检测到，且浓度呈年龄依赖性增加。人源 sPD-L1 在血清中具有独特的蛋白形式，基质金属蛋白酶抑制剂（MMPI）可抑制 sPD-L1 的产生。此外，sPD-L1 可以特异性地与 PD-1 结合。总之，这些数据表明人血清中循环 sPD-L1 的存在可能在免疫调节中发挥重要作用。
