Recombinant interleukin-6 inhibits the growth of rat mesangial cells in culture.

Murine recombinant interleukin-6 (IL-6) inhibited [3H]thymidine uptake by cultured rat mesangial cells in a dose-dependent manner in the presence of 0.5% fetal bovine serum (FBS). The inhibitory effect of IL-6 on the growth of mesangial cells was also confirmed by a change in cell numbers. In the presence of increased concentrations of FBS (5% or 10%), the effect of IL-6 was not prominent. IL-6 showed no effects on intracellular Ca2+ levels of mesangial cells. IL-6 gene expression was rapidly induced in the "quiescent" mesangial cells by exposure to 20% FBS. These observations support the premise that IL-6 is synthesized in mesangial cells and inhibits the growth of mesangial cells in an autocrine manner.