Table 1.
Effect of transient secretion of IL-2 and scIL-12 by NXS2 neuroblastoma cells on the induction of a systemic protective immunity
| Vaccine* | Day of challenge | Bone marrow metastasis† | Liver‡ metastasis | Liver weight,§ mg |
|---|---|---|---|---|
| None | 14 | 2,2,2,2,2,2 | 4,4,4,4,4,4 | 3950 ± 310 |
| NXS2 S empty plasmid | 14 | 2,2,2,2,1,1 | 4,4,4,2,2,1 | 2558 ± 425 |
| NXS2 S IL2 | 14 | 2,2,2,2,2,1 | 4,4,4,4,3,1 | 3600 ± 673 |
| NXS2 H2A IL2 | 14 | 2,2,2,2 | 4,4,4,4 | 4337 ± 452 |
| None | 7 | 2,2,2,1 | 4,4,4,4 | 3466 ± 115 |
| NXS2 S empty plasmid | 7 | 2,2,2 | 4,4,4 | 3465 ± 205 |
| NXS2 H2A IL2 | 7 | 2,2,2,2,2,2 | 4,4,4,4,4,2 | 3032 ± 215 |
| NXS2 H2A empty plasmid | 7 | 2,2,2,2,1,1 | 4,4,4,4,3,2 | 3053 ± 265 |
| NXS2 S empty plasmid | 7 | 2,2,2,1,1,1 | 4,4,4,3,2,1 | 2043 ± 201 |
| NXS2 S scIL-12¶ | 7 | 0,0,0,0,0,1 | 0,0,0,0,1,2 | 1290 ± 74 |
| NXS2 H2A scIL-12¶ | 7 | 0,0,0,0,1,1 | 0,0,0,0,1,2 | 1312 ± 31 |
Mice were injected s.c. with 2 × 106 NXS2 cells genetically engineered to produce IL-2 and scIL-12 and challenged by a lethal intravenous injection of 5 × 104 NXS2 wild-type cells 7 and 14 days after initial inoculation.
NXS2 cells were transfected with Superfect (S) or histone H2A (H2A) using IL-2 and scIL-12 plasmid DNA and compared to empty plasmid controls.
Bone marrow metastases were staged according to results obtained by high and low sensitivity tyrosine hydroxylase RT-PCR as described in Materials and Methods.
Liver metastases were staged according to the percentage of metastatic liver surface: 0, 0%; 1, <0–25%; 2, 25–50%; 3, 50–75%; 4, >75%.
Liver weight was determined on fresh specimens and expressed as mean values ± SE.
Differences in bone marrow staging, liver metastasis, and liver weights between experimental groups and control groups were statistically significant (P < 0.01).