Suppression of macrophage responses to bacterial lipopolysaccharide by a non-secretory form of secretory leukocyte protease inhibitor

Expression of secretory leukocyte protease inhibitor (SLPI) suppresses the ability of macrophages to respond to bacterial lipoyolysaccharide (LPS). He re, addition of recombinant or native SLPI to the extracellular medium was non-suppressive, while transfection with a non-secretory form of SLPI was f ully suppressive, an effect overcome by treatment with interferon-gamma. A portion of the SLPI produced by untransfected macrophages was localized in the cytosol. Thus, SLPI can act intracellularly to block macrophage activat ion by LPS. (C) 1999 Elsevier Science B.V. All rights reserved.