Preparation of CD33 targeted bispecific- and trispecific-T cell engagers and their cytotoxicity on leukemia cells / 中华血液学杂志

Objective: To investigate the effect of CD33-targeted bi-specific and tri-specific T-cell engagers on T-cell proliferation and explore their cytotoxicity on leukemia cells. Methods: The CD33-targeted bi-specific T-cell engager (CD33-BiTE) and tri-specific T-cell engager (CD33-TriTE) expression vectors were successfully constructed and expressed through a eukaryotic cell expression system. CD33-BiTE and CD33-TriTE were purified by affinity chromatography. The effects of CD33-BiTE and CD33-TriTE on T cells were analyzed through in vitro experiments. Results: ① CD33-BiTE and CD33-TriTE were successfully constructed and purified and could compete with flow cytometry antibodies for binding to the target cells. ② After 12 days of co-culture with CD33-BiTE and CD33-TriTE, the number of human T cells were expanded to 33.89±19.46 and 81.56±23.62 folds, respectively. CD33-TriTE induced a stronger proliferation of T cells than CD33-BiTE (P<0.05) . ③ Both CD33-BiTE and CD33-TriTE induced specific dose-dependent cytotoxicity on CD33(+) leukemia cells. ④ Compared to CD33-TriTE, leukemia cells were prone to express PD-L1 when co-cultured with T cells and CD33-BiTE. CD33-TriTE induced powerful cytotoxicity on leukemia cells with high PD-L1 expression. Conclusion: CD33-BiTE and CD33-TriTE expression vectors were constructed, and fusion proteins were expressed in eukaryotic cells. Our results support the proliferative and activating effects of BiTE and TriTE on T cells. Compared to that of CD33-BiTE, CD33-TriTE induced a stronger proliferative effect on T cells and a more powerful cytotoxicity on leukemia cells with high PD-L1 expression.

Functional investigation of chimeric antigen receptor T cells targeting LMP1 antigen / 中华血液学杂志

Objective: This study aimed to create a type of CAR-T cells that targets LMP1 antigen and study its immunotherapeutic effect on LMP1-positive hematological malignancies. Methods: To generate LMP1 CAR-T cells, a plasmid expressing LMP1 CAR was created using molecular cloning technology, and T cells were infected with LMP1 CAR lentivirus. The effects of LMP1 CAR-T cells on specific cytotoxicity against LMP1-positive tumor cell lines infected with the EB virus had been confirmed. Results: ① LMP1 protein expressing on EB virus-positive lymphoma cells surface was verified. ② The LMP1 CAR-expressing plasmid was created, and LMP1 CAR-T cells were obtained by infecting T cells with a lentivirus packaging system, with an infection efficiency of more than 80% . ③LMP1 CAR-T cells have a 4∶1 effect-to-target ratio in killing LMP1-positive lymphoma cells. The killing effect of LMP1 CAR-T cells on Raji cells was enhanced after 48 h of coculture, but there was no significant killing effect on Ramos, which are LMP1-negative lymphoma cells. ④After coculture with LMP1-positive lymphoma cells at a ratio of 1∶1 for 5 h, the degranulation effect was enhanced. The proportion of CD107a(+) T cells in the LMP1 CAR-T cell treatment group was significantly higher than that in the vector-T cell group [ (13.25±2.94) % vs (1.55±0.05) % , t=3.972, P=0.017]. ⑤After coculture with LMP1-positive lymphoma cells, the proportion of CD69(+) and CD25(+) T cells in the LMP1 CAR-T cell group was significantly higher than that in vector-T cell group [ (7.40±0.41) % vs (3.48±0.47) % , t=6.268, P=0.003; (73.00±4.73) % vs (57.67±2.60) % , t=2.842, P=0.047]. ⑥After coculture with LMP1-positive lymphoma cells, cytokine secretion in the LMP1 CAR-T cell group was higher than that in the vector-T cell group [interferon-gamma: (703±73) ng/L vs (422±87) ng/L, t=2.478, P=0.068; tumor necrosis factor-alpha: (215±35) ng/L vs (125±2) ng/L, t=2.536, P=0.064]. Conclusion: In this study, we found that the LMP1 protein is only found on the surface of the EBV-positive tumor cell. Simultaneously, we created an LMP1 CAR-expressing plasmid and obtained LMP1 CAR-T cells by infecting T cells with a lentivirus packaging system. Furthermore, we demonstrated that LMP1 CAR-T cells could specifically kill LMP1-positive tumor cells in vitro. The degranulation and activation effects of LMP1 CAR-T cells were enhanced after coculture with LMP1-positive tumor cells, indicating a potential clinical application.