Effects of anti-gp130 mAbs on vIL-6–mediated DNA synthesis.

(A) BAF-130 cells (2 × 10⁴ cells/well) were stimulated with various concentrations of hIL-6/sIL-6R, MBPvIL6, or MBP for 48 hours. [³H]-Thymidine was added during the final 6 hours of culture. (B) Failure of a vIL-6 deletion to stimulate BAF-130 cells or to inhibit the binding of vIL-6 or hIL-6/sIL-6R to gp130. The BAF-130 cells were stimulated with MBPvIL-6 (200 ng/mL) or hIL-6 (25 ng/mL)/sIL-6R (50 ng/mL) in the presence of increasing amounts of MBPvIL-6 M3, which encodes Asp81 to Cys93. The BAF-130 cells were also stimulated with MBPvIL-6 M3 alone (18-40 000 ng/mL). (C) Effects of selected anti-gp130 mAb on hIL-6–induced and vIL-6–induced DNA synthesis. The BAF-130 cells were stimulated with MBPvIL6 (500 ng/mL) or hIL-6 (50 ng/mL)/sIL-6R (100 ng/mL) in the presence of anti-gp130 mAbs (B-R3, B-P4, and B-P8) or control IgG (78-5000 ng/mL). The 100% value corresponds to proliferation in the absence of antibody. The results reflect the mean of counts per minute of triplicate cultures; SD was within 10% of the mean. Representative data of 3 independent experiments are shown.