Treatment with GCV to purge Ad.DF3-tk–transduced OCI-My5 and RPMI 8226 MM cells within BM MNCs. To construct standard curves for measuring residual viable tumor cell contamination after purging, OCI-My5 cells (A) or RPMI 8226 MM cells (B; 0 to 1 × 106 cells) were incubated in triplicate with 3H-TdR (1 μCi) for 12 hours, harvested, and analyzed on a β-counter. OCI-My5 (C) and RPMI 8226 MM cells (D; 2 × 105 cells) were mixed with γ-irradiated (2.0 Gy) normal BM MNCs (2 × 106 cells). BM MNCs containing tumor cells were transduced with Ad.DF3-tk at MOI = 1, MOI = 10, or MOI = 100 or with Ad.CMV-tk at MOI = 10 for 2 hours, washed out for 10 hours, and treated with GCV at 0 (□), 0.5 (▨), 5 (░), or 50 (▪) μmol/L for 36 hours. 3H-TdR incorporation was measured as described above and compared with that for nontransfected tumor cell in BM MNC controls. CESS (E) and JY (F) EBV-transformed B cells, which do not express adenoviral receptors, served as negative controls. All experiments were performed in triplicate. Log depeletion of OCI-My5 (G) and RPMI 8226 (H) MM cells with Ad.DF3-tk at MOI = 100 and 50 μmol/L GCV is shown.
