RAT MESANGIAL CELLS HAVE A SELECTIVE ROLE IN MACROPHAGE RECRUITMENT AND ACTIVATION

In proliferative glomerulonephritis glomeruli are the target of an inf lammatory reaction involving macrophage recruitment and activation. We examined the role of mesangial cells in this process. Supernatants fr om basal, IL 1, IFN-tau or LPS-stimulated rat mesangial cells (MCS) we re tested for chemotactic, colony-stimulating and activation effects o n macrophages in vitro. IL-1-stimulated MCS produced a macrophage chem oattractant (p = 0.007 compared with basal MCS) and MCP-1 mRNA was det ected in IL-1-stimulated mesangial cells. LPS or IL-1-stimulated MCS p roduced colony-stimulating activity (LPS p < 0.05, IL-1 p < 0.01, comp ared with basal MCS or control supernatant, CS). Macrophage activation , assessed by nitric oxide generation, was suppressed. This evidence f rom functional bioassays supports a selective role for mesangial cells in the control of macrophage-induced glomerular injury, whereby activ ated mesangial cells participate in the recruitment and proliferation of infiltrating macrophages, and suppresses at least one field of macr ophage activation, namely nitric oxide generation.