The stimulating effect of nerve growth factor (NGF) on phagocytosis, p
arasite killing, and interleukin-1 beta (IL-1 beta) production of muri
ne peritoneal macrophages was assessed. In the presence of various dos
es of NGF, macrophages showed the increased phagocytosis of both nonsp
ecific hydrophilic microspheres and sheep red blood cells (SRBC) opson
ized with anti-SRBC antibodies (Ab) or complement in a dose-dependent
manner. NGF also enhanced killing of Leishmania donovani promastigotes
by macrophages, and its ability was comparable with that of an optima
l dose of recombinant granulocyte-macrophage colony-stimulating factor
or recombinant interferon-gamma. The addition of NGF to peritoneal ma
crophages and monocyte-macrophage J774A.1 cells led to a significant r
elease of IL-1 beta in a dose-dependent manner and expression of IL-1
beta mRNA. Because pretreatment of peritoneal macrophages and J774A.1
cells with K-252a, a tyrosine kinase inhibitor, completely suppressed
these NGF-mediated stimulating effects and p140(trk) phosphorylation a
nd because flow cytometric analysis with specific Ab against two disti
nct NGF receptors showed the expression of p140(trk) unlike p75(LNGFR)
. On the surface of macrophages, the stimulating activity of NGF to mu
rine macrophages may be mediated through p140(trk). Thus, NGF may act
as an activator for murine macrophages in the process of inflammatory
and immune actions. (C) 1996 by The American Society of Hematology.