Soluble immune complexes stimulate production of interleukin-1 by cultured rat glomerular mesangial cells

Interleukin-1 (IL-1) is a pleiotropic factor, eliciting a broad set of immunologic and inflammatory events. We have previously shown that IL-1 is present in inflamed glomeruli. To evaluate factors that might regulate of IL-1 production, we tested the effects of substances accessible to mesangial cells (MC): immune complexes (IC) are known to modulate MC function. We have attempted to assess the ability of soluble IC derived from rat glomerular basement membrane to induce the production of IL-1. When isolated MC were incubated with the soluble IC, substantial amount of IL-1 could be detected in the supernatants as measured by the mouse thymocyte assay. To block the effect of prostaglandins on the IL-1 assay, we cultured the MC with the addition of indomethacin and assayed IL-1 activity in the culture supernatants. The use of indomethacin resulted in a further increase in IL-1 production. These biological activities were neutralized by a specific antibody to IL-1. In the present report, we show that IC represent important sources of stimulation of MC for the production of IL-1. We speculate that IC could augment local inflammatory responses in the kidney partly due to their capacity to induce the production of IL-1.