The CD274 Knockout THP-1 Cell Line is a CRISPR/Cas9-edited knockout cell line engineered for the disruption of the CD274 gene, which encodes the immune checkpoint ligand PD-L1. This cell line provides a complete loss-of-function model by eliminating PD-L1 protein expression in the well-characterized THP-1 monocytic background, thereby abrogating PD-1-mediated immunosuppressive signaling. The knockout product facilitates precise investigation of the PD-1/PD-L1 axis and enables rigorous functional studies in cancer immunology and immune cell regulation.
THP-1 is a human acute monocytic leukemia cell line that serves as a widely used model for monocyte and macrophage biology, including phagocytosis, inflammatory responses, and immune cell differentiation. Upon stimulation with agents such as phorbol esters or cytokines, THP-1 cells acquire macrophage-like characteristics, making them highly suitable for studying innate immune functions and tumor microenvironment interactions. The monocytic origin and capacity for polarization render THP-1 an ideal host for exploring immune checkpoint pathways that regulate immune surveillance and tolerance.
At the molecular level, CD274 (PD-L1) functions as a transmembrane ligand that binds to its cognate receptor PD-1 (PDCD1) on activated T cells, delivering inhibitory signals that suppress T-cell receptor?Cproximal kinases such as ZAP70 and LCK. This interaction triggers SHP2 phosphatase recruitment, which dephosphorylates key signaling intermediates and attenuates downstream PI3K/AKT and MAPK pathways. Expression of CD274 is transcriptionally regulated by upstream signals including IFN-??, IL-6, and TNF-??, often mediated through transcription factors STAT3, NF-??B, and AP-1. Additionally, CD274 engages CD80 (B7-1) as a secondary binding partner, further modulating immune responses. Thus, CD274 operates at the intersection of multiple signaling cascades, including JAK/STAT, PI3K/AKT, and NF-??B pathways, to promote immune tolerance and tumor immune evasion.
In the THP-1 background, CD274 knockout eliminates PD-L1-driven immunosuppression, allowing dissection of PD-1/PD-L1 blockade effects on T-cell activation, proliferation, and cytokine production in co-culture systems. This model is particularly valuable for studying how monocytic cells contribute to the immune milieu in solid tumors and hematological malignancies. By removing the inhibitory ligand, researchers can assess the restoration of T-cell effector functions and the potential for enhanced anti-tumor immunity, as well as investigate the role of PD-L1 in macrophage polarization and phagocytosis.
Typical applications include high-throughput screening of immune checkpoint inhibitors, functional evaluation of combination therapies, and mechanistic studies of PD-L1 regulation in inflammatory environments. Representative assays involve flow cytometric verification of PD-L1 loss, ELISA-based quantification of IL-2 and IFN-?? secretion in T-cell/THP-1 co-cultures, CFSE-based T-cell proliferation assays, and cytotoxicity measurements. The knockout line is also suitable for western blot analysis of PD-L1, RT-qPCR profiling of CD274 mRNA, and PD-1/PD-L1 binding assays. For additional information or to request pricing, please contact Ascent Research.
