Oncostatin M stimulates proliferation in B9 hybridoma cells: potential role of oncostatin M in plasmacytoma development.

Oncostatin M was found to stimulate the IL-6-addicted hybridoma line B9. Leukaemia inhibitory factor did not stimulate proliferation of this line. Both of these factors bind to the gp130 of the IL-6 receptor. In another cell line that is stimulated by LIF (DA.1), neither IL-6 nor oncostatin M stimulated proliferation. Previously it had been thought that the gp130 alone is sufficient to bind ligand and transduce signal and that oncostatin M could bind to and activate the LIF receptor, but these data show this is not always the case. Mice primed with Pristane were found to have IL-6 in their sera and peritoneal fluid only at a few time points following Pristane treatment; this was determined by IL-6-specific ELISA. When the same samples were analysed on IL-6-addicted B9 cells, stimulatory activity was found at all time points. When the Pristane-primed samples were assayed for oncostatin M activity in the A375 melanoma assay, there was oncostatin M activity at various time points. IL-6 did not have activity on the A375 cells. These data indicate that oncostatin M play a role in the generation of plasmacytoma in vivo.