Fig 2: SECTM1 CAR expression led to fratricide of CD7+ cells. (A) Schematic presentation of the MOCK and SECTM1 CAR domains. (B) Representative CAR expression of the T cells was detected by flow cytometric on day 3 after transduction, and the percentage of positive cells is presented in the histogram. (C). The number of T cells was counted on day 3 after transduction. (D) IFNγ secreted into the supernatant of transduced T cell culture medium was measured by ELISA on day 3 after transduction. (E) CD7 expression of NT, MOCK, and SECTM1 CAR T cells was measured by flow cytometry on day 3 after transduction. The percentage of positive cells compared with an isotype control (ISO) is presented in the histogram. Data in panels C and D are presented as the mean ± SD of triplicates.

Fig 3: Lysis of CD7+ ALL and AML cells by SECTM1 CAR T cells. (A) CD7 expression in ALL cell lines (CCRF-CEM and MOLT4), and AML cell lines (KG-1a and Kasumi-3) was analyzed by flow cytometry. (B) Tumor cells were cocultured with CAR T cells at various E:T ratios, and cytotoxicity was measured at 20 hours by flow cytometry. (C) Cytokines released into the coculture supernatant described in panel B of an E:T ratio of 2:1 was detected by ELISA. Left, the IFNγ level; right, the TNFα level. Data in panels B and C are presented as the mean ± SD of triplicates.

Fig 4: SECTM1 CAR T cells eradicated CD7+ primary T-ALL cells. (A) CD7 expression level of primary leukemic blasts from 4 patients with T-ALL, the percentage of CD7+ cells were showed compared with ISO. (B) The remaining live tumor cells were calculated to detect the cytotoxicity of SECTM1 CAR T cells against T-ALL primary leukemic blasts. (C) IFNγ and TNFα released by the CAR T cells in the experiment described in panel B was detected by ELISA. Left, the IFNγ level; right, the TNFα level. Data in panels B and C are presented as the mean ± SD of triplicates.