Journal: Journal of translational medicine

Article Title: Unraveling resistance mechanisms in anti-CD19 chimeric antigen receptor-T therapy for B-ALL: a novel in vitro model and insights into target antigen dynamics.

doi: 10.1186/s12967-024-05254-z

Figure Lengend Snippet: Fig. 5 Observation of CD19-BBζ-CAR expression in relapsed Nalm-6 cells and salvage treatment. A Detection of FMC63 and CD247 transcripts and 4-1BB gene of CAR in CD19+ Nalm-6 (red) and relapsed CD19− Nalm-6 cells (blue) by qRT-PCR. Data of left bar graph represent the relative quantification using ACTB as the internal reference. Error bars represent s.d. The data are the representative of three independent experiments. B Expression of CD19 and CAR on CD19+ Nalm-6 cells and relapsed CD19− Nalm-6 cells analyzed by flow cytometry (representative of 3 experiments). Merge Graphs, the blue dots represent CD19− Nalm-6 cells and the red dots represent Nalm-6 cells. C Confocal imaging of Nalm-6 cells and relapsed CD19− Nalm-6 cells using Alexa Flour 488-conjugated anti-CD19 antibody (green), Alexa Flour 647-conjugated anti-CAR19 antibody (red), and DAPI (blue). D Lentiviral integration sites of CAR transduced Nalm-6 cells were analyzed by linear-amplification mediated PCR (LAM-PCR) and visualized with Circos plots. The integration sites across the genome and genomic features were shown from outer to inner circle: (1) cytogenetic bands; (2) genes that harbor these integration sites along with a bar chart showing the reads of integration sites; (3) the distribution of integration sites, with colored circles representing different gene functional regions of the host sequence: purple for promoter region, green for intron region, and red for distal intergenic region. E Phenotype changes of Nalm-6 cells transduced with small amount of CD19 CAR lentiviruses detected by flow cytometry over time. Gating was based on the same cells stained with isotype-matched antibody. F Dynamics of CD19− B phenotype in relapsed cells after co-culture with different ratios (5×, 20×) of Nalm-6 cells. Gating was based on the same cells stained with isotype-matched antibody. G Relapsed CD19− Nalm-6 cells were tested by qPCR specific for VSV-G sequence. H Comparison of in vitro efficacy of CD19-, CD22-, CD19/CD22- and CD22×CD19- CAR T cells. Cocultures with the relapsed cells were performed at 1:5, 1:1, and 5:1 E: T ratios, and lysis efficacies were detected by the LDH release assay Declarations

Article Snippet: The cells were then washed twice and stained with phycoerythrin (PE) streptavidin (BD bioscience, USA) for 15 min. CART-22 cells and CART-22/19 cells were washed once and incubated with CD22 Fc Alexa Fluor® 647 Protein (R&D Systems, USA) for 15 min. To detect in vitro cytotoxicity of CART-19 cells, transduced and untransduced T cells were co-cultured with Nalm-6 cells (total 1 × 106 cells) at E: T ratios (0.2:1, 0.5:1, 1:1, 5:1) for 6, 24 and 72 h. Cells were pipetted to incubate with antibodies for 30 min at room temperature in the dark and washed twice with PBS.

Techniques: Expressing, Quantitative RT-PCR, Quantitative Proteomics, Flow Cytometry, Imaging, Amplification, Functional Assay, Sequencing, Transduction, Staining, Co-Culture Assay, Comparison, In Vitro, Lysis, Lactate Dehydrogenase Assay