Adding and deleting genes to enhance T-cell function. Retro- and lentiviral gene transfer can be used to redirect the specificity of T cells and the metabolic functions, response to chemokines, and cytokine secretion. Gene disruption technologies can be used to delete endogenous TCR genes, HLA genes, and genes involved in negative T-cell regulation. The indicated genes are simply examples, and the editing technologies can be applied to add or disrupt any gene involved in T-cell function.