The molecular and immunological properties of tissue-resident resting CD4 T cells are understudied due to the lack of suitable gene editing methods. Here, we describe the ex vivo culture and gene editing methodology ediTONSIL for CD4 T cells from human tonsils. Optimized CRISPR-Cas9 RNP nucleofection results in knockout efficacies of over 90% without requiring exogenous activation. Editing can be performed on multiple cell types in bulk cultures or on isolated CD4 T cells that can be labeled …