INDUCTION OF CYSTINE TRANSPORT ACTIVITY IN MOUSE PERITONEAL-MACROPHAGES BY BACTERIAL LIPOPOLYSACCHARIDE

The transport of cystine has been investigated in mouse peritoneal macrophages cultured in vitro. The transport activity for cystine was very low in freshly isolated macrophages but was potently induced during culture in the presence of bacterial lipopolysaccharide (LPS) at concentrations as low as 0.1 ng/ml. The transport activity for cystine was enhanced when the cells were incubated with tumour necrosis factor-alpha (TNF-alpha), but not with interferon-gamma (IFN-gamma) or interleukin-1. IFN-gamma was rather repressive in the induction of the activity by LPS or TNF-alpha. The transport activity for cystine induced by LPS has been characterized. Cystine was transported mainly by a Na+-independent system and the uptake of cystine was inhibited by extracellular glutamate and homocysteate, but not by aspartate, indicating that the transport of cystine in macrophages treated with LPS is mediated by System x(e)(-). Glutathione content of the macrophages increased when they were exposed to LPS, and this increase was, at least in part, attributable to the induced activity of the cystine transport.