CSF analysis for patient 1. (A) Trends in WBCs in the CSF over time after CAR T-cell infusion and time points of intervention. (B) Flow cytometry plots of final CAR T-cell product and CSF. T cells in the CSF at day 13 postinfusion were predominantly CD4⁺ non-CAR T cells. Preinfusion final CAR T-cell product phenotype after staining cells with a combination of markers for CD3, CD4, CD8, and protein L (to detect the CAR) and analyzing the stained cells by flow cytometry (left panels). The same panel of markers was used to analyze CSF collected at day 13 postinfusion (right panels). The plots were based on gated CD3⁺ T cells. ARA-C, cytarabine; MTX, methotrexate.