Human CD19 Stable Cell Line - Hela

Autologous T cells expressing CD19-specific chimeric antigen receptors (CARs) have been shown to have significant efficacy in the treatment of B-cell malignancies. Here, researchers constructed FLAG-tagged CD19-specific CAR-T cells (CD19-FLAG) and compared them with untagged CAR-T cells in vitro and in vivo experiments to understand their efficacy against solid tumors and hematological tumor cells. For solid tumors, the researchers used HeLa cervical carcinoma cells engineered to overexpress CD19 (HeLa-CD19); for hematological tumors, Raji Burkitt lymphoma cells that endogenously express CD19 were used. Like untagged CD19 CAR-T cells, CD19-FLAG CAR-T cells expanded more than 100-fold in in vitro culture and showed strong cytolytic activity against both HeLa-CD19 cells and Raji cells in vitro. CD19-FLAG CAR-T cells also secreted significantly more IFN-γ and IL-2 than control T cells. In vivo experiments, CD19-FLAG CAR-T cells significantly inhibited the growth of HeLa-CD19 solid tumors, increased the level of caspase-3 for tumor lysis, and achieved systemic expansion. CD19-FLAG CAR-T cells also significantly reduced Raji tumor burden and prolonged the survival of mice. These results demonstrate the powerful efficacy of FLAG-tagged CD19 CAR-T cells in solid tumor and blood tumor models.

Here, the researchers tested the ability of CD19 and CD19-FLAG CAR-T cells to kill CD19-bearing target cells using two human cell lines: Raji, a B-cell line that endogenously expresses CD19, and HeLa, a cervical cancer line that has been genetically engineered to overexpress CD19. Cytolysis was detected using the real-time cell analysis (RTCA) xCELLigence system, which measures the impedance of the target cell monolayer over time; as target cells are killed by effector cells, the impedance of the monolayer decreases. Both CD19 and CD19-FLAG CAR-T cells exhibited significant cytolytic activity against Raji cells (Figure 1A) and Hela-CD19 cells (Figure 1B), but not against HeLa cells (Figure 1C). In contrast, mock CAR-T cells and untransduced T cells showed no significant cytolytic activity against any target cells. Thus, both CD19 and CD19-FLAG CAR-T cells exhibited potent CD19-dependent cytolytic activity.

Figure 1. CD19-FLAG CAR-T cells are highly cytolytic for CD19+ cancer cells. (Berahovich R, et al., 2017)