Neutralizing activity of mAbs against vIL-6.

(A) Exponentially growing B9 cells (2 × 10³ cells/well) were cultured in medium supplemented with MBPvIL-6 (100 ng/mL) with or without anti-vIL-6 Ab (0.8-10 μg/mL). [³H]-Thymidine was added during the final 6 hours of culture. The results represent the mean radioactivity of triplicate cultures; SD was within 5% of the mean. Representative data of 2 independent experiments are shown. (B) vIL-6 induces human IgM production in SKW6.4 cells. SKW6.4 cells (1 × 10⁴ cells/well) were incubated in the presence of hIL-6 or MBPvIL-6 at various concentrations, and human IgM production in the supernatants was measured by human IgM ELISA. (C) Effect of mAbs against vIL-6 on IgM secretion by SKW6.4 cells. SKW6.4 cells were incubated in the presence of MBPvIL-6 (2 μg/mL) and mAbs against vIL-6 (0-10 μg/mL). The results represent the mean of triplicate cultures; error bars represent SDs. The asterisk denotes the occurrence of a significant decrease in IgM secretion in cultures containing anti-vIL-6 mAbs (P < .0005) compared to cultures containing MBPvIL-6 (2 μg/mL) alone.