MOUSE PARENCHYMAL LIVER-CELLS IN CULTURE SECRETE A GROWTH INHIBITOR FOR MYELOMA CELLS

Methods: Growth inhibitory activity in the conditioned medium of mouse parenchymal liver cells was examined in three strains of myeloma cell s. Results: Two strains of myeloma cells were highly sensitive to a lo w concentration of mouse parenchymal liver cell derived growth inhibit or, whereas one strain was resistant to the same concentration. Interf eron-alpha beta and transforming growth factor-beta activity were dete cted in mouse parenchymal liver cells, while interferon-gamma and tumo r necrosis factor-alpha were not. The growth suppression exerted by mo use parenchymal liver cell derived growth inhibitor in the three myelo ma strains was distinct from that exerted by transforming growth facto r-beta, tumor necrosis factor-alpha, interferon-alpha beta and interfe ron-gamma. The mouse parenchymal liver cell derived growth inhibitor w as eluted with a peak activity in the 18 kDa range and focused into pI values of 3.8-4.0, and it was lost when mouse parenchymal liver cells were treated with heat or trypsin. Conclusion: These results indicate that mouse parenchymal liver cell derived growth inhibitor differs fr om the well-characterized growth inhibitors, transforming growth facto r-beta, tumor necrosis factor-alpha, interferon-alpha beta and interfe ron-gamma.