TABLE 3.
Role of bacterial products in cytotoxicity and inhibition of cytotoxic activity
| Treatment | Suilysin production | % Cytotoxicitya |
|---|---|---|
| Medium alone | 0 (±0) | |
| Strain 31533 | Yes | 73 (±16) |
| Strain 89-1591 | No | 0 (±0) |
| Strain 31533 (killed) | No | 3 (±4) |
| Strain 89-1591 (killed) | No | 8 (±7) |
| Strain 31533 (supernatant) | Yes | 72 (±7) |
| Strain 89-1591 (supernatant) | No | 0 (±0) |
| Purified suilysin | 1 μg/ml | 81 (±16) |
| 2.5 μg/ml | 90 (±9) | |
| 5 μg/ml | 100 (±1) | |
| Medium alone | + cholesterol | 2 (±2) |
| Strain 31533 (supernatant) | + cholesterol | 0 (±0) |
| Strain 89-1591 (supernatant) | + cholesterol | 0 (±0) |
| Purified suilysin (5 μg/ml) | + cholesterol | 9 (±3) |
a
Cytotoxicity in cultures of infected J774 cells was determined by measurement of LDH release after 3 h of bacterium-cell contact at an infection ratio of 100 bacteria/cell (107 CFU/well). Data are expressed as the percentage of cytotoxicity (± standard deviations) in infected wells with respect to control wells with macrophages alone (n = 4). Cholesterol inhibition was performed as follows 1 h at 37°C with 100 μg of ethanol-soluble cholesterol/ml.