The CD59 Knockout K-562 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout population from the K-562 chronic myelogenous leukemia (CML) cell line, featuring targeted disruption of the CD59 gene. This product eliminates expression of the GPI-anchored complement inhibitory protein CD59, offering a loss-of-function tool for investigating complement-dependent cytotoxicity (CDC) and immune evasion. The polyclonal nature retains diverse editing events, providing a representative population for functional genomics without clonal artifacts.
K-562 is an immortalized lymphoblast line isolated from the pleural effusion of a 53-year-old female with CML in blast crisis. It harbors the Philadelphia chromosome with BCR-ABL fusion, driving constitutive tyrosine kinase activity central to leukemogenesis. Widely used as a model for CML, K-562 cells exhibit robust suspension growth and are amenable to genetic manipulation, making them a standard host for CRISPR-based gene disruption to study leukemia biology and drug responses.
CD59 functions as a key negative regulator of the terminal complement pathway by binding complement components C8?? and C9 within the assembling membrane attack complex (MAC). This interaction prevents C9 polymerization and subsequent MAC insertion into the plasma membrane, thereby inhibiting complement-dependent lysis. CD59 expression is induced by pro-inflammatory cytokines TNF-??, IFN-??, and IL-1??, acting via transcription factors NF-??B and STAT1. The protein is tethered to the cell surface via a glycosylphosphatidylinositol (GPI) anchor, linking its function to GPI biosynthesis. Besides C8 and C9, CD59 interacts with CD2, and its deficiency leads to unchecked MAC formation, rendering cells susceptible to complement-mediated cytotoxicity.
In the K-562 CML background, CD59 knockout creates a clinically relevant model for investigating complement evasion strategies in leukemia. Upregulation of CD59 is a common mechanism by which cancer cells resist antibody-driven CDC, contributing to immune escape. Disrupting CD59 in these BCR-ABL-positive cells sensitizes them to complement attack, enabling dissection of therapeutic antibody efficacy and complement-dependent cytotoxicity. Furthermore, this model mimics aspects of paroxysmal nocturnal hemoglobinuria (PNH), a disorder caused by GPI-anchored protein deficiency, facilitating studies on complement dysregulation and GPI anchor pathophysiology.
Key applications include complement-mediated lysis assays, flow cytometry for CD59 expression validation, western blotting, and functional studies with anti-CD59 blocking antibodies. The polyclonal population is suitable for CRISPR validation, pooled genetic screens, and investigating innate immunity, GPI-anchored protein function, and cancer immune checkpoint mechanisms. For technical inquiries, please contact Ascent Research.
