E1 protein is detected in modified CTLs after specific activation. (A) Immunofluorescence: C-RE (E1-transduced CTLs) and nontransduced CTLs were activated with autologous LCLs, fixed, permeabilized, and stained with an antibody specific for E1a or with an isotype control. 293 cells were used as a positive control for E1a production. Cells were analyzed by flow cytometry. (B) Western blot analysis: 4 × 106 activated E1-transduced CTLs (C-RE) were lysed and the proteins separated on a gel (lanes 2-3). M58 monoclonal antibody was used to detect the E1a protein. 293 cell extract was used as a positive control (lanes 4-5), and nonactivated CTL (nonactivated C-RE) extract was used as a negative control (lane 1). M1 indicates negative population; M2, positive population. Results are shown as the percentage of positive cells.
