Figure 3.
Modified iPSC-CTLs exhibit high proliferation capacity while recapitulating the phenotypic changes of primary CTLs
(A−C) Growth curve (A) and flow cytometric profile (B and C) of iPSC-CTLs, the parental T cell clone, and healthy donor-derived primary naive CTLs in PHA-PBMC-feeder expansion culture. (A) The indicated cells were expanded and enumerated repeatedly at 2-week intervals in the presence of 5 ng/mL IL-7, 5 ng/mL IL-15, and other supplements described in Materials and methods. (B and C) The binding of the cognate peptide-HLA complex and expression of CD8 subunits, TCR (B), and T cell differentiation-related markers (C) after 4 (B) or 1 or 10 (C) rounds of expansion. (D and E) Intracellular granzyme B expression (D) and IL-2 and IFN-γ production and cytotoxic activity (E) of iPSC-CTLs after the indicated rounds of expansion. The frozen stocks of iPSC-CTLs were made at different times, but they were thawed, rested, and expanded once side by side in advance of the flow cytometry or the 51Cr release killing assay against 1 μM peptide-pulsed K562-A24 at an E/T = 1 (IL-2, IFN-γ) and 10 (cytotoxicity) (mean ± SD). (A−C) Data are representative of two independent experiments using TKT3V1-7- and H254SeV3-derived iPSC-CTLs, whereas data of (D) and (E) are the result of a single experiment using TKT3V1-7-derived iPSC-CTLs. (The results of H254SeV3- and H2531SeV3-derived iPSC-CTLs are shown in Figure S15.)