CD300LD Knockout HAP1 Polyclonal Cells are a human polyclonal knockout cell population created via CRISPR/Cas9-mediated disruption of the CD300LD gene in the HAP1 near-haploid cell line. These cells provide a loss-of-function model for the inhibitory immune receptor CD300LD, which contains ITIMs and negatively regulates myeloid cell activation. The polyclonal pool provides a broad spectrum of genetic disruptions, suitable for population-based functional studies without clonal isolation.
HAP1 is a human near-haploid cell line derived from the male KBM-7 CML line. It grows adherently with fibroblast-like morphology and carries a single copy of most chromosomes, facilitating straightforward gene knockout without interference from residual wild-type alleles. Its myeloid origin makes it relevant for studying immune receptor signaling pathways.
CD300LD acts as an inhibitory receptor on myeloid cells. Ligand engagement promotes phosphorylation of its ITIMs by Src kinases (e.g., Lyn, Fyn), leading to recruitment of phosphatases SHP-1 and SHP-2. These phosphatases dephosphorylate downstream targets, including Syk and components of PI3K/AKT and MAPK cascades, thereby suppressing cellular activation and cytokine production. The receptor may also interact with SHIP1 and Grb2. Through these mechanisms, CD300LD serves as an immune checkpoint dampening pro-inflammatory responses.
In HAP1 cells, CD300LD knockout allows clear dissection of ITIM-mediated inhibitory signaling due to the near-haploid background, minimizing compensatory gene effects. This model is valuable for exploring myeloid cell regulation in cancer immune evasion, inflammation, and for investigating the receptor??s role in dampening activating signals triggered by Fc receptors or cytokine receptors.
Applications include immunoblotting to confirm loss of CD300LD and assess ITIM phosphorylation, co-immunoprecipitation of SHP-1/SHP-2, flow cytometry for surface receptor profiling, and phospho-signaling analysis (e.g., phospho-Syk, phospho-ERK). Functional readouts such as cytokine secretion (IL-6, TNF-??), phagocytosis, and NFAT/NF-??B reporter assays can be employed. The cells are also useful for ligand identification and drug screening. For additional details, contact Ascent Research.
