Lymphocyte expansion after CAR T-cell infusion. (A) ALC proliferation kinetics and concurrent peripheral smear images of atypical lymphocytes in (eventual) SR patient HP-101. (B) ALC kinetics of the entire cohort (n = 164) showing lag, expansion, and contraction phases. Black dashed line depicts the mean. The y-axes are depicted in a linear scale similar to ALC graphs in the electronic medical record. Split axes are used to highlight the entire spectrum of peak ALCs. (C) Spectrum of atypical lymphocytes after CAR infusion. Atypical features include markedly basophilic cytoplasm (HP-123 and HP-8), cytoplasmic projections (HP-101), polarized granules (HP-119), chunky granules (HP-149), and azurophilic rods (HP-185). Patient code and days post–CAR infusion are shown in parentheses. Representative CellaVision images at ×500 original magnification. Background RBCs demonstrate uniformity of smears and magnification. (D) Violin plots (median, quartile ranges, and distribution) of baseline and peak and 1-month ALC across the cohort (n = 164; ***P < .0001, Kruskal-Wallis test). (E) Timeline of peak ALC across the cohort (n = 164). Red symbols depict NRs. The 2 NRs with the highest ALCs underwent reinfusion of CAR T cells or pembrolizumab during the first month. Different shapes indicate individual patients. (F) Increased CD8 T cells at peak expansion compared with that observed before and 1 month after CAR infusion (n = 10 cases). (G) Violin plots showing increased CD8/CD4 ratio at day 28 compared with baseline across the cohort (n = 166; ***P < .0001, Wilcoxon test).