The CD22 Knockout HAP1 Polyclonal Cells constitute a CRISPR/Cas9-edited polyclonal knockout cell population derived from the near-haploid human HAP1 cell line, engineered for loss-of-function studies of the CD22 gene. This polyclonal format provides a heterogeneous pool of edited cells, enabling bulk analyses and pooled screening approaches in hematopoietic cell models. By disrupting the CD22 locus through CRISPR/Cas9-mediated gene disruption, these cells offer a versatile tool for investigating the regulatory roles of CD22 in B-cell receptor (BCR) signaling and immune tolerance without the need for clonal isolation.
The HAP1 host cell line is a chronic myeloid leukemia-derived near-haploid human cell line, originally adapted from the KBM-7 line, and is characterized by TP53 null status and BCR-ABL positivity. Its unique haploid karyotype makes it particularly advantageous for genetic knockout studies, as it eliminates complications from diploid gene redundancy, facilitating clear phenotype interpretation. Widely employed as a hematopoietic model for high-throughput CRISPR screens, HAP1 cells maintain active BCR-related signaling pathways, making them suitable for examining B-cell regulatory circuits despite their myeloid origin.
CD22 is an inhibitory co-receptor that binds ??2,6-linked sialic acids and, upon BCR activation, undergoes phosphorylation by Lyn tyrosine kinase. This phosphorylation recruits the tyrosine phosphatase SHP-1, which dephosphorylates key signaling mediators such as Syk and the co-receptor CD19, thereby dampening downstream MAPK/ERK pathway activity and calcium flux. CD22 also interacts with SHIP, an inositol phosphatase, further attenuating BCR-driven signals. Collectively, this negative regulatory network sets activation thresholds essential for B-cell tolerance.
In the HAP1 context, CD22 knockout polyclonal cells provide a standardized model to dissect BCR inhibitory signaling independently of B-cell lineage-specific factors. The haploid background ensures loss-of-function effects are directly attributable to CD22 disruption, while the polyclonal nature enables cost-effective population-based assays without clone-specific artifacts. Researchers can use this model to study mechanisms of autoimmune diseases like systemic lupus erythematosus, explore CD22 as a therapeutic target in B-cell acute lymphoblastic leukemia and non-Hodgkin lymphoma, and perform pooled CRISPR screens for modifiers of BCR signal strength.
Typical applications include western blotting to confirm CD22 protein loss and assess SHP-1 levels, flow cytometry for surface CD22 detection, and calcium flux assays to quantify BCR responsiveness. Phospho-flow analysis can measure Lyn and Syk phosphorylation kinetics, while ELISA-based evaluations of antibody secretion and cell proliferation assays provide functional readouts of BCR output. This CD22 knockout polyclonal HAP1 cell population thus supports mechanistic investigations and drug discovery efforts targeting B-cell inhibitory pathways. For additional product specifications or customized solutions, please contact Ascent Research.
