FIG. 4.

Comparison of free PMB versus PMB-IgG in TNF release inhibition assay. Cultured human monocytes release a fixed amount of TNF in response to incubation with 20 ng of pure E. coli O111:B4 LPS per ml. This experiment compares the abilities of varying concentrations (total protein) of either free PMB or the PMB-IgG conjugate to inhibit TNF release. Both reagents were found to inhibit the LPS-induced TNF release in a dose-dependent fashion. The free PMB was approximately 33 times more potent than the conjugate based on total protein weight. This suggests that there is approximately 3 μg of active PMB per 100 μg of PMB-IgG conjugate. Unconjugated IgG had no activity in this assay.