Recombinant interleukin-1 alpha inhibits the growth of rat mesangial cells in culture.

We have investigated the effect of interleukin-1 (IL-1) on the growth of mesangial cells isolated from rat kidney. Recombinant IL-1 alpha inhibited 3H-thymidine uptake by mesangial cells in a dose-dependent manner in the presence of either 0.5% or 5% fetal bovine serum (FBS). In the presence of high concentration of FBS (10%), the effect of IL-1 was not prominent. The inhibitory effect of IL-1 on the growth of mesangial cells was also confirmed by a change in cell numbers and measurements of protein synthesis with 3H-leucine. IL-1-induced inhibition of mesangial cell growth was not affected by indomethacin. IL-1 showed no effects on intracellular Ca2+ levels in mesangial cells. These observations indicate that IL-1 inhibits the growth of mesangial cells, and thus may play a protective role for mesangial cells from abnormal proliferation in some pathophysiological states.