Inhibition of 1-Hour Anti-IgM–Induced Apoptosis by the Addition of Soluble IgM Inhibitor at Various Time Intervals After Initial Exposure of Cells to Ligand
| Soluble IgM Addition . | Percentage Annexin-Positive . | Percentage of Inhibition3-150 . | |
|---|---|---|---|
| Medium . | Mu53 Anti-IgM . | ||
| No IgM | 18.9 | 64.4 | — |
| t = 0 | 19.1 | 18.6 | 100 |
| t = 2 min | 19.5 | 26.2 | 85 |
| t = 5 min | 19.0 | 27.1 | 82 |
| t = 10 min | 19.8 | 31.5 | 74 |
| t = 20 min | 18.3 | 34.8 | 64 |
| t = 30 min | 19.5 | 45.8 | 42 |
| Soluble IgM Addition . | Percentage Annexin-Positive . | Percentage of Inhibition3-150 . | |
|---|---|---|---|
| Medium . | Mu53 Anti-IgM . | ||
| No IgM | 18.9 | 64.4 | — |
| t = 0 | 19.1 | 18.6 | 100 |
| t = 2 min | 19.5 | 26.2 | 85 |
| t = 5 min | 19.0 | 27.1 | 82 |
| t = 10 min | 19.8 | 31.5 | 74 |
| t = 20 min | 18.3 | 34.8 | 64 |
| t = 30 min | 19.5 | 45.8 | 42 |
Purified human IgM myeloma protein was added (final concentration, 250 μg/mL) to cultures containing 105 Ramos cells in medium alone or with MoAb Mu53 anti-IgM (5 μg/mL; MoAb:cell ratio of 1 μg/105 cells). Annexin-positive cells were assessed after 1 hour of culture. The results given are representative of three experiments.
Percentage of inhibition of specific anti-IgM–triggered apoptosis in the presence of soluble IgM was calculated as follows: % inhibition = 100 − ([% annexin + cells in anti-IgM cultures with IgM present − % annexin + cells in medium cultures with IgM present] ÷ [% annexin + cells in anti-IgM cultures with no IgM − % annexin + cells in medium cultures with no IgM]).