The HLA-DQB1 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal cell population generated from the near-haploid HAP1 human cell line, featuring targeted disruption of the HLA-DQB1 gene. This heterogeneous knockout pool provides a robust loss-of-function model for studying MHC class II function without the selection of a single clonal isolate. Gene disruption abrogates expression of the MHC-II beta chain, eliminating surface presentation capability and enabling population-level functional assays.
HAP1 is a chronic myelogenous leukemia-derived near-haploid cell line with an adherent growth morphology and fewer than 30 chromosomes. Originating from the KBM-7 line, its haploid genome facilitates single-allele knockout and has made it a widely used platform for genetic screens and functional genomics. The cells retain responsiveness to interferon-gamma, which normally upregulates MHC-II via the master regulator CIITA, but HLA-DQB1 knockout renders them MHC-II-deficient even upon stimulation.
HLA-DQB1 encodes the beta chain of MHC class II heterodimers that present exogenous peptide antigens to CD4+ T cells, initiating adaptive immune responses. Transcription is controlled by CIITA, which is activated by upstream factors including the RFX complex (RFX5, RFXAP, RFXANK), IFN-gamma signaling, CREB1, and NF-Y. Within the endocytic pathway, CD74 chaperones MHC-II molecules, while HLA-DM and HLA-DO regulate peptide loading. The knockout disrupts assembly and surface transport of MHC-II, thereby blocking antigen presentation and downstream T cell activation, including IL-2 and IFN-gamma secretion.
In the HAP1 context, HLA-DQB1 knockout eliminates MHC-II surface expression, creating a clean background for dissecting antigen presentation pathways or reconstituting MHC-II via ectopic expression. The polyclonal nature supports pooled CRISPR screens to identify novel regulators of MHC-II trafficking or immune evasion, and it models aspects of MHC class II deficiency and autoimmune diseases such as celiac disease, type 1 diabetes, multiple sclerosis, and systemic lupus erythematosus, where MHC-II alleles confer genetic risk.
Typical applications include flow cytometry for MHC-II quantification, T cell co-culture assays measuring IL-2 or IFN-gamma via ELISA, and immunofluorescence for localization studies. These cells are compatible with high-content screening for immunomodulatory compounds and genetic screens for synthetic interactions in an MHC-II-negative background. For further information, please contact Ascent Research.
