HLA-Knockout: Enabling Allele-Specific Knockout of HLA Class I Genes for Immunogenic Engineering.

The interaction between T-cell receptors (TCRs) and antigenic peptides presented by HLA molecules is fundamental to adaptive immunity. However, the extreme polymorphism of HLA genes poses major challenges for transplantation, antigen discovery, immunotherapy and studies of allele-specific function. Although CRISPR/Cas9 has transformed gene editing, existing sgRNA design tools are not optimised for knockout of HLA Class I genes due to their high rates of polymorphism. To address this, we developed HLA-Knockout (https://hlaknockout.rutgers.edu), a novel web-based tool that enables precise, allele-specific targeting of HLA Class I genes. HLA-Knockout retrieves user-defined HLA sequences from the IPD-IMGT/HLA database and applies stringent design criteria, including mismatch filtering and PAM disruption analysis, to ensure high specificity and minimal off-target effects on non-target HLA Class I alleles. Using HLA-Knockout, we achieved efficient single- and double-allele HLA Class I knockouts in human cells without disrupting non-target HLA Class I alleles. Functional assays confirmed allele-specific loss of antigen-specific TCR activation, validating the platform's utility. HLA-Knockout provides a unique resource for dissecting HLA-restricted immune interactions and has broad applications in transplantation biology, autoimmunity and cancer immunotherapy.