TABLE 2.
Parameter estimates from regression of ratios of mRNA for TNF-α, IL-1β, and IL-6 to mRNA for β-actin obtained from LPS-stimulated U937 cells on level of methylprednisolone (MP)
| Cytokine | LPS concn (ng/ml) | Cytokine/β-actin ratio
|
Regression equationc | Effective dose of MP (μg/ml)d | ||
|---|---|---|---|---|---|---|
| Minimuma | Maximuma | 50% reductionb | ||||
| TNF-α | 100 | 77.0 | 185.0 | 92.50 | 181.73 − 0.44(MP) | 203 |
| 1,000 | 99.5 | 318.5 | 159.25 | 326.02 − 0.92(MP) | 181 | |
| 5,000 | 129.0 | 481.5 | 240.75 | 468.06 − 1.40(MP) | 162 | |
| 10,000 | 137.5 | 566.0 | 283.00 | 570.84 − 1.79(MP) | 161 | |
| Mean | 177 | |||||
| IL-1β | 100 | 96.0 | 272.5 | 136.25 | 247.97 − 0.67(MP) | 167 |
| 1,000 | 140.0 | 384.5 | 192.25 | 376.37 − 1.00(MP) | 184 | |
| 5,000 | 150.0 | 392.5 | 246.25 | 497.26 − 1.46(MP) | 172 | |
| 10,000 | 189.5 | 597.0 | 298.50 | 612.94 − 1.81(MP) | 174 | |
| Mean | 174 | |||||
| IL-6 | 100 | 79.5 | 252.5 | 126.25 | 245.03 − 0.73(MP) | 163 |
| 1,000 | 119.0 | 348.0 | 174.00 | 338.86 − 0.96(MP) | 172 | |
| 5,000 | 151.5 | 488.5 | 244.25 | 512.30 − 1.39(MP) | 193 | |
| 10,000 | 168.5 | 625.5 | 312.75 | 643.36 − 1.95(MP) | 170 | |
| Mean | 175 | |||||
| Overall mean | 175 | |||||
| Overall median | 172 | |||||
a
Median of duplicate measurements.
b
50% reduction = (median maximum expression)/2.
c
Ŷ = α̂ − β̂(level of MP), where Ŷ is the ratio of mRNA for a particular cytokine, α̂ is the intercept, and β̂ is the regression coefficient.
d
After the value of a 50% reduction was substituted for Ŷ, the effective dose was obtained by solving for the unknown level of MP.