CD7^KOCD7 CAR T cells are cytotoxic against normal T cells and NK cells but can themselves respond to viral antigens. (A) Control or full-length CD7^KO CD7 CAR T cells were cocultured with eFluor670-labeled autologous PBMC for 24 hours, and the frequency of T and NK cells was measured by flow cytometry. Dot plots show the frequency of gated CD19⁺ B cells (top) and CD56⁺CD3⁻ NK cells and CD3⁺ T cells (bottom) at the end of coculture. (B) Total numbers of autologous B cells, NK cells, and T cells at the end of coculture with autologous CD7^KO CD7 CAR T cells was quantified by flow cytometry using counting beads. Data represent 2 independent experiments with n = 3 donors in each. (C) Nontransduced, CD7^KO and CD7^KO CD7 CAR T cells were stimulated with pepmixes from cytomegalovirus, Epstein-Barr virus, and adenovirus, and the number of IFNγ⁺ spot-forming cells was measured by ELISPOT. Individual data from 3 donors are shown as a means of triplicate determinations. (D) CD4⁺ and CD8⁺ T cells were MACS-purified and separately assayed for IFNγ production in response to pepmixes. AdV, adenovirus; CMV, cytomegalovirus; EBV, Epstein-Barr virus; Neg., negative; Pos., positive; SFC, spot-forming cells. ***P < .001.