HHLA2 Knockout THP-1 Polyclonal Cells are a CRISPR/Cas9-edited cell population in which the HHLA2 gene has been disrupted in the human monocytic leukemia cell line THP-1. Delivered as a polyclonal pool, this model avoids the biases of single-cell cloning and provides a representative knockout bulk culture for functional studies where the overall loss of HHLA2 expression allows examination of its dual role in immune checkpoint regulation.
THP-1 is a suspension cell line originating from acute monocytic leukemia that is widely used to model monocyte and macrophage biology. These cells retain key monocytic properties, including the capacity to differentiate into macrophage-like cells upon treatment with phorbol esters, and they are responsive to inflammatory mediators such as TNF-alpha, IFN-gamma, and IL-1beta. Their well-characterized signaling networks and ease of genetic manipulation make THP-1 an ideal host for investigating gene function in innate immunity.
HHLA2 (HERV-H LTR-associating 2) is a B7 family immunoregulatory ligand with opposing effects on immune cells. When bound to its receptor TMIGD2 (CD28H) on T cells, HHLA2 initiates a costimulatory cascade that activates PI3K/AKT and NF-kB signaling, leading to T cell proliferation and effector cytokine secretion; downstream targets include mTOR. Alternatively, engagement of the inhibitory receptor KIR3DL3 on NK cells and certain T cell subsets by HHLA2 suppresses cytotoxic activity and cytokine production. The expression of HHLA2 is upregulated by TNF-alpha, IFN-gamma, and IL-1beta through NF-kB-dependent mechanisms, situating it at a critical junction between immune activation and tolerance.
Knockout of HHLA2 in THP-1 cells creates a versatile platform to study how loss of this ligand affects the interplay between monocyte-lineage cells and lymphocytes. Differentiated THP-1 cells can act as surrogate antigen-presenting cells or inflammatory macrophages, and ablation of HHLA2 disrupts both the TMIGD2-mediated costimulatory and KIR3DL3-dependent inhibitory pathways. This enables investigation of the consequences for T cell and NK cell functional responses, as well as the dissection of upstream regulators and downstream signaling events such as PI3K/AKT and NF-kB activation under controlled experimental conditions.
Typical applications include T cell co-culture experiments to quantify proliferation and cytokine secretion by flow cytometry or ELISA; NK cell cytotoxicity assays; receptor binding studies; western blot analysis of PI3K/AKT and NF-kB pathway components; and transcriptomic profiling (RNA-seq) to identify HHLA2-regulated gene networks. The polyclonal knockout cells are also suitable for drug sensitivity testing with anti-HHLA2 antibodies or small-molecule inhibitors, supporting cancer immunotherapy research, immune checkpoint exploration, and target validation. For further information, please contact Ascent Research.
