FIG. 2.
IL-2-transduced TILs secrete large amounts of IL-2 and have prolonged survival after IL-2 withdrawal. (A) Patient (pt) TILs, either untransduced (UT) or transduced (Td) with the IL-2 gene from the day of infusion, were thawed and tested the next day in a 4-day assay for IL-2 production. Cells were cultured in medium alone and on anti-CD3 (OKT3 at 1 μg/ml)-coated plates, in the presence of anti-Tac to inhibit uptake of IL-2 by the TILs. IL-2 concentrations in the supernatants were determined by ELISA. Asterisks (*) denote that samples were not determined because of unavailability. (B) Untransduced (UT) and IL-2-transduced (Td) TILs were washed extensively on the day of infusion and placed in medium without IL-2. Viable cells were enumerated every 3–7 days by trypan blue exclusion and cell culture medium was refreshed weekly by replacing half of the spent medium with fresh medium.