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PD-L1/CD9 Exosome ELISA Kit

Quantification of PD-L1 positive exosomes in blood samples and cell culture supernatants

This product is a two-step sandwich ELISA, which utilizes high-performance anti-PD-L1 and anti-CD9 antibodies to directly detect PD-L1 molecules on the surface of exosomes in human blood samples and cell culture supernatants.

Tumor cells evade the immune surveillance by up-regulating surface expression of PD-L1, which interacts with PD-1 on T cells to elicit the immune checkpoint response1),2). In recent years, anti-PD-1 antibody drugs and anti-PD-L1 antibody drugs that inhibit this signal transduction have been confirmed to have clinical efficacy and safety in various solid cancers by enhancing T cell activation3), 4).

A well-known predictor of the effects of these immune checkpoint inhibitors is PD-L1 expression on cancer cells. The PD-L1 IHC test is used as a companion diagnostics for measuring PD-L1 expression rate in cancer tissues and cells.

As a general matter, because IHC tests are highly invasive, research on liquid biopsies using exosomes is also in progress.

Exosomal PD-L1 has the same membrane topology as the cell surface PD-L1, with its extracellular domain exposed on the surface of the exosomes5). Exosomal PD-L1 binds PD-1 in a concentration-dependent manner. The level of PD-L1 on the circulating exosomes was significantly higher in patients with metastatic melanoma than that in healthy donors5).

However, these methods require exosome purification using ultracentrifugation, there were no rapid and convenient direct measurement methods until now.

Kit Principle

This ELISA kit uses two-step sandwich ELISA principle. The ELISA plate provided in this kit has been pre-coated with an anti-CD9 antibody.

First, samples were added onto the plate to capture exosomes by the anti-CD9 antibody.

Next, HRP conjugated anti-PD-L1 antibody will be added to react with PD-L1 on the surface of exosomes.

Finally, substrate will be added, then measure the coloring by the plate reader to quantitate sample exosomes.

Features

  • ●Directly quantitate exosomal PD-L1 in human blood samples or cell culture supernatant.
  • ●No special equipment is required. Standard microplate reader capable of reading at 450nm will do the job.
  • ●Utilize PD-L1/CD9 fusion protein (Standard Protein), instead of unstable/hard to store exosome itself, to implement stability and reproducibility.
  • ●Normalization with a standard curve using PD-L1/CD9 fusion protein (Standard Protein) enable to relative quantitate each sample.
  • ●Detect human PD-L1 positive exosomes by two-step sandwich method using immobilized anti-CD9 antibody and HRP conjugated anti-PD-L1 antibody.

Data

Figure 1. Standard curve

As an example, the graph of absorbance (OD450) against standard concentration is drawn as shown in Figure 1. However, draw a new standard curve for each assay to calculate the concentration in the sample.

(Plotted is the value obtained by subtracting the blank absorbance from the absorbance of each standard protein concentration)

Product List

PD-L1 positive Exosome ELISA Kit

Product nameCatalog Number
PD-L1/CD9 Exosome ELISA Kit, Human HAK-HELPDL109-1

References

  1. 1) H. Dong, S. E. Strome, D. R. Salomao, H. Tamura, F. Hirano, D. B. Flies, P. C. Roche, J. Lu,G. Zhu, K. Tamada, V. A. Lennon, E. Celis, L. Chen: Nat Med., 8, 793 (2002).
  2. 2) L. Chen, X. Han: J Clin Invest., 125, 3384(2015).
  3. 3) S. L. Topalian, F. S. Hodi, J. R. Brahmer, et al.: N Engl J Med., 366, 2443 (2012).
  4. 4) J. R. Brahmer, S. S. Tykodi, L. Q. Chow, et al.: N Engl J Med., 366, 2455 (2012).
  5. 5) G. Chen, A. C. Huang, W. Zhang, et al.: Nature, 560, 382 (2018).

Product List

Exosome Related Antibodies

Product nameCatalog Number
Anti human CD63 Antibody, Clone A1-9A2 HAK-ANTI-CD63-A1-9A2
Anti human CD90 Antibody, Clone A6-10G9 HAK-ANTI-CD90-A6-10G9
Anti dog CD9 Antibody, Clone A1-2G10 HAK-ANTI-DCD9-2G10-1
Anti dog CD63 Antibody, Clone A2-1A4 HAK-ANTI-DCD63-1A4-1