INFgamma stimulates arginine transport through system y+L in human monocytes

Freshly isolated human monocytes transport L-arginine mostly through a sodium independent, NEM insensitive pathway inhibited by L-leucine in the presence, but not in the absence of sodium. Interferon-gamma (IFNgamma) stimulates this pathway, identifiable with system y(+)L, and markedly enhances the expression of SLC7A7, the gene that encodes for system y(+)L subunit y+LAT1, but not of SLC7A6, that codes for the alternative subunit y+LAT2. System y(+) plays a minor role in arginine uptake by monocytes and the expression of system y(+)-related genes, SLC7A1 and SLC7A2, is not changed by IFNgamma. These results demonstrate that system y(+)L is sensitive to IFNgamma. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.