J Vet Sci.  2021 Sep;22(5):e75. 10.4142/jvs.2021.22.e75.

Evaluation of circulating PD-1 and PD-L1 as diagnostic biomarkers in dogs with tumors

• Song DW
• Ro WB
• Park HM

• KMID: 2520770
• DOI: http://doi.org/10.4142/jvs.2021.22.e75

Abstract

Background
Programmed cell death protein-1 (PD-1) and programmed cell death ligand-1 (PD-L1) have important roles in tumor evasion of the immune system.
Objectives
This study aimed to assess the diagnostic utility of circulating PD-1 and PD-L1 levels in healthy dogs and dogs with tumors.
Methods
Circulating PD-1 and PD-L1 levels in the serum of 71 dogs with tumors were compared with those of 52 healthy dogs by performing enzyme-linked immunosorbent assay (ELISA).
Results
The ELISA results revealed higher circulating PD-1 and PD-L1 levels in dogs with tumors (2.9 [2.2–3.7] ng/mL; median [IQR] and 2.4 [1.4–4.4] ng/mL, respectively) than in healthy dogs (2.4 [1.9–3.0] ng/mL; p = 0.012 and 1.4 [0.9–2.1] ng/mL; p < 0.001, respectively). Especially, there was a significant difference in circulating PD-1 levels between healthy dogs and dogs with malignant epithelial tumors (2.4 [1.9–3.0] ng/mL and 3.1 [2.6–4.4] ng/mL, respectively; p < 0.01). In addition, there was a significant difference in circulating PD-L1 levels between healthy dogs and dogs with lymphomas (1.4 [0.9–2.1] ng/mL and 2.7 [1.6–5.8] ng/mL, respectively; p < 0.001).
Conclusion
This study indicates that circulating PD-1 and PD-L1 have potential as tumor diagnostic biomarkers in dogs with tumors.

Keyword

Dog; tumor; biomarker; programmed cell death protein; ligand