B2M Knockout CAL-27 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the human oral squamous cell carcinoma cell line CAL-27. This product features targeted disruption of the B2M gene, which encodes beta-2-microglobulin (??2M), the invariant light chain of major histocompatibility complex class I (MHC-I) molecules. As a polyclonal pool, the population comprises a heterogeneous mixture of edited alleles, providing a robust loss-of-function model without reliance on a single clonal isolate. The knockout abolishes ??2M protein expression, leading to a functional deficiency in MHC-I assembly and surface presentation.
The parental CAL-27 cell line was established from a poorly differentiated squamous cell carcinoma of the tongue in a 56-year-old male patient. CAL-27 serves as a widely utilized model for head and neck squamous cell carcinoma (HNSCC), particularly oral tongue tumors, and is employed to investigate tumor biology, metastatic potential, and therapeutic responses. Its well-characterized genomic and transcriptomic landscape, combined with a robust in vitro and in vivo growth profile, makes it an ideal host for gene perturbation studies focusing on immune evasion and oncogenic signalling.
Beta-2-microglobulin is an essential component of the MHC-I heterotrimeric complex, non-covalently associating with the polymorphic HLA-A, -B, and -C heavy chains and the peptide-binding groove. This interaction, stabilized by the peptide-loading complex comprising TAP1/2, tapasin, calreticulin, and ERp57, is mandatory for egress of functional MHC-I molecules to the cell surface. B2M gene expression is transcriptionally regulated by upstream signals including interferon gamma (IFNG), NF-??B, CIITA, STAT1, and IRF1, integrating inflammatory cues with antigen presentation. Loss of ??2M abrogates surface MHC-I expression and disrupts CD8+ T cell recognition, while simultaneously altering the repertoire of natural killer (NK) cell ligands such as MICA/B and ULBP, thereby modulating immune synapse formation.
In the CAL-27 background, B2M disruption generates a powerful platform for parsing the interplay between adaptive and innate antitumor immunity in HNSCC. The absence of MHC-I surface expression renders these cells resistant to CD8+ T cell-mediated lysis but hypersensitive to NK cell cytotoxicity through missing-self recognition. This dichotomy allows researchers to dissect the contributions of cytotoxic T lymphocytes versus NK cells in tumor control, evaluate the impact of the immune microenvironment, and model immune pressure in a clinically relevant squamous carcinoma context.
This polyclonal knockout model is suited for diverse experimental paradigms, including mechanistic studies of immune evasion, development of universal donor cells with reduced immunogenicity, and preclinical assessment of T-cell receptor-independent immunotherapies. Representative assays include flow cytometric quantification of MHC-I surface loss, western blot confirmation of ??2M depletion, NK cell cytotoxicity and T cell activation co-culture assays, xenograft tumor growth monitoring in immunocompromised or humanized mouse models, and spatial immune infiltrate analysis by immunofluorescence. For further information or to discuss custom applications, please contact Ascent Research.
