Development of a sandwich ELISA for evaluating soluble PD-L1 (CD274) in human sera of different ages as well as supernatants of PD-L1+ cell lines

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Animals
  • B7-H1 Antigen / blood*
  • Cell Line
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Humans
  • Limit of Detection
  • Matrix Metalloproteinase 1 / blood
  • Mice
  • Mice, Inbred BALB C
  • Reproducibility of Results
  • Tumor Escape


  • B7-H1 Antigen
  • CD274 protein, human
  • Cd274 protein, mouse
  • Matrix Metalloproteinase 1