Cross-reactivity of anti-human programmed cell death ligand 1 (PD-L1) monoclonal antibody, clone 28-8 against feline PD-L1

• Published in: Journal of Veterinary Medical Science Vol. 85; no. 6; pp. 592 - 600
• Main Authors: KAGAWA, Yumiko, MIZUNO, Takuya, NISHIBORI, Shoma, IGASE, Masaya, UCHIDA, Kazuyuki, NAKAGAWA, Takayuki, SAKURAI, Masashi
• Format: Journal Article
• Language: English
• Published: Japan JAPANESE SOCIETY OF VETERINARY SCIENCE 2023; Japan Science and Technology Agency; The Japanese Society of Veterinary Science
• Subjects: Animals; Antibodies, Monoclonal; antibody; Apoptosis; B7-H1 Antigen; Cancer therapies; Cats; Cell death; Clinical Pathology; Clone Cells - chemistry; Clone Cells - metabolism; Cross-reactivity; feline; Flow cytometry; Immune checkpoint; Immunohistochemistry; Immunoprecipitation; Immunotherapy; Ligands; Lymph nodes; Macrophages; Mice; Monoclonal antibodies; NIH 3T3 Cells; PD-L1 protein; programmed cell death ligand 1; Tumor cells; Tumor microenvironment; Tumors; antibody; feline; immunohistochemistry; programmed cell death ligand 1; immune checkpoint
• ISSN: 0916-7250; 1347-7439; 1347-7439
• DOI: 10.1292/jvms.23-0003

Immunotherapy is a breakthrough in human cancer therapy and has become a major concern in veterinary oncology. However, in cats, many unclear points of the tumor microenvironment exist, including immune checkpoint molecules. A reason is that very few monoclonal antibodies have been proven to react with feline molecules. Therefore, this study investigated whether anti-human programmed cell death ligand 1 (PD-L1) monoclonal antibody, clone 28-8, which is currently commercially available, can also recognize feline PD-L1 by flow cytometry, immunoprecipitation, and immunohistochemical (IHC) staining. We confirmed that the antibody’s specificity by flow cytometry and immunoprecipitation using NIH3T3 cells transfected with feline PD-L1. Additionally, we revealed that PD-L1 was expressed on the surface of some feline cell lines by flow cytometry and clone 28-8 antibody unbound to the cells where feline PD-L1 was knocked out. Furthermore, IHC analysis revealed that PD-L1 was expressed in macrophages in the spleen and lymph nodes from healthy cats and mast cell tumor cells. Therefore, we indicated that the clone 28-8 antibody is a valuable tool in detecting feline PD-L1, and further analysis of tumor tissues is expected in the future.