Human monocytes lose 5-lipoxygenase and its activating protein as
they mature into monocyte-derived macrophages in vitro.
Ring, William L., Carl A. Riddick, Joseph R. Baker, Dominic A. Munafo,
and Timothy D. Bigby.
Department of Medicine, University of California, San Diego and
Department of Veteran Affairs Medical Center, San Diego, California
92161
APStracts 3:0054C, 1996.
Previous studies in mononuclear phagocytes have shown that macrophages
have substantially greater 5-lipoxygenase activity than monocytes and
that this is associated with greater amounts of 5-lipoxygenase and
its activating protein (FLAP). The aim of this study was to examine
the effect of mononuclear phagocyte maturation in vitro on 5
-lipoxygenase expression. At baseline, monocytes had significant 5
-lipoxygenase activity, but then lost all detectable 5-lipoxygenase
activity over seven days. Immunoblot and Northern blot analysis
revealed that immunoreactive protein and mRNA for both 5-lipoxygenase
and FLAP were significantly decreased over time. These studies
demonstrate that in vitro differentiation of monocytes into a
macrophage phenotype is not accompanied by the enhanced expression of
5-lipoxygenase and FLAP seen in macrophages derived from in vivo
sources. In fact, baseline expression of 5-lipoxygenase and FLAP by
monocytes is lost in vitro. These studies have clear implications for
the use of cultured monocytes as a model of macrophages, and they
also further our understanding of the regulation of the 5
-lipoxygenase pathway.
Received 11 December 1995; accepted in final form 26 January
1996.
APS Manuscript Number C741-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 14 February 96