Inverse Targeting of Receptor-Negative Cells in a Mixed Population
| . | Experiment No. . | EXA (%) . | SCFXA (%) . | 4070A (%) . |
|---|---|---|---|---|
| A431 | 1 | <1 | 50 | 100 |
| 2 | <1 | 50 | 100 | |
| 3 | <1 | 50 | 100 | |
| TF-1 | 1 | 72 | 3 | 92 |
| 2 | 20 | 2 | 53 | |
| 3 | 35 | 6 | 56 | |
| A431 | 1 | <1 | 50 | 100 |
| 2 | <1 | 50 | 100 | |
| 3 | <1 | 50 | 100 | |
| HMC-1 | 1 | 61 | 3 | 66 |
| 2 | 20 | 2 | 29 | |
| 3 | 29 | 8 | 57 |
| . | Experiment No. . | EXA (%) . | SCFXA (%) . | 4070A (%) . |
|---|---|---|---|---|
| A431 | 1 | <1 | 50 | 100 |
| 2 | <1 | 50 | 100 | |
| 3 | <1 | 50 | 100 | |
| TF-1 | 1 | 72 | 3 | 92 |
| 2 | 20 | 2 | 53 | |
| 3 | 35 | 6 | 56 | |
| A431 | 1 | <1 | 50 | 100 |
| 2 | <1 | 50 | 100 | |
| 3 | <1 | 50 | 100 | |
| HMC-1 | 1 | 61 | 3 | 66 |
| 2 | 20 | 2 | 29 | |
| 3 | 29 | 8 | 57 |
Two milliliters of EXA, SCFXA, or 4070A viral supernatant was used to infect a mixed population of adherent A431 cells (kit-negative, EGF-R–positive) and either HMC-1 or TF-1 suspension cells (kit-positive, EGF-R–negative). After infection, the cells were separated and propagated in their respective media for 72 hours before X-gal staining. Infection with the wild-type control virus gave high titers on both cell types. In contrast, the chimeric vectors could discriminate between cell types. SCFXA vectors preferentially infected the Kit-negative A431 cells, whereas EXA vectors preferentially infected the EGF-R–negative TF-1 or HMC-1 cells. Data showing the individual titers from 3 separate experiments are shown in this table. Titers are shown as percentage blue cells.