Table 1. IL-6. IFN-α and IGF-1 are myeloma cell survival factors.
Myeloma cells were harvested during the exponential growth phase with IL-6 and FCS, IL-6 and FCS starved for 1 hour and then cultured for 2, 6, 24 or 48 hours with no cytokine, 2 ng/mL of IL-6, 200 U/mL of IFN-α or 100 ng/mL of IGF-1 in RPMI1640 culture medium and 1% BSA. At the end of the culture, cells were stained with FITC-annexin V to determine the percentage of apoptotic cells and analyzed with a FACScan. Results are mean values ± SD of 3–6 different experiments. In all these experiments, the percentage of viable cells assayed by trypan blue exclusion was not significantly affected during the first 24 hours of culture.
Except when indicated (*), the mean percentage of apoptotic cells in the culture group with cytokines is significantly different (P < .05) from corresponding control groups (Control at 2 h, 6 h, 24 h or 48 h), as determined by a Student t-test for pairs.
| ANNEXIN VT(%) | |||||
|---|---|---|---|---|---|
| Hours of culture | 0 | 2 | 6 | 24 | |
| XG-1 | Co | 34 ± 10 | 69 ± 11 | 74 ± 8 | 81 ± 10 |
| IL-6 | 59 ± 14* | 61 ± 10 | 61 ± 14 | ||
| IFN- α | 59 ± 14 | 59 ± 11 | 60 ± 13 | ||
| IGF-1 | 58 ± 12 | 60 ± 11 | 64 ± 13 | ||
| 0 | 2 | 6 | 24 | ||
| XG-2 | Co | 25 ± 6 | 49 ± 12 | 67 ± 17 | 82 ± 15 |
| IL-6 | 43 ± 15* | 55 ± 18 | 58 ± 18 | ||
| IFN- α | 42 ± 14* | 49 ± 18 | 48 ± 14 | ||
| IGF-1 | 44 ± 17* | 59 ± 16 | 68 ± 19 | ||
| 0 | 6 | 24 | 48 | ||
| XG-6 | Co | 14 ± 1 | 28 ± 6 | 52 ± 27 | 58 ± 24 |
| IL-6 | 21 ± 7 | 36 ± 25 | 36 ± 23 | ||
| IFN- α | 19 ± 7 | 36 ± 25 | 41 ± 24 | ||
| IGF-1 | 24 ± 6 | 46 ± 28 | 48 ± 24 | ||
| 0 | 2 | 6 | 24 | ||
| XG-13 | Co | 28 ± 5 | 39 ± 7 | 51 ± 3 | 62 ± 14 |
| IL-6 | 36 ± 5* | 39 ± 7 | 45 ± 17 | ||
| IFN- α | 34 ± 5* | 35 ± 6 | 44 ± 14 | ||
| IGF-1 | 32 ± 5 | 35 ± 6 | 42 ± 14 | ||