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Infection and Immunity, November 1998, p. 5314-5321, Vol. 66, No. 11
Molecular Infectious Disease
Group1 and the
Molecular Immunology
Group,2 Institute of Molecular Medicine,
John Radcliffe Hospital, Oxford, United Kingdom
Received 4 February 1998/Returned for modification 22 April
1998/Accepted 29 July 1998
Inducible synthesis of nitric oxide (NO) by macrophages is an
important mechanism of the host defense against intracellular infection
in mice, but the evidence for significant levels of inducible NO
production by human macrophages is controversial. Here we report that
the human promyelocytic cell line HL-60, when differentiated to a
macrophage-like phenotype, acquires the ability to produce substantial
amounts of NO on stimulation with LPS or 1,25-dihydroxyvitamin
D3 (1,25-D3) in the absence of activating factors such as gamma interferon. Expression of the inducible nitric
oxide synthase (NOS2) was confirmed by sequencing of the reverse
transcription-PCR product from stimulated HL-60 cells. Kinetic studies
after lipopolysaccharide stimulation show that NOS2 mRNA levels rise
within 3 to 6 h, that conversion of [14C]arginine to
[14C]citrulline is maximal at 5 to 6 days, and that
levels of reactive nitrogen intermediates stabilize at around 20 µM
at 7 to 8 days. We find that 1,25-D3 acts to suppress the
growth of Mycobacterium tuberculosis in these cells and
that this effect is inhibited by
NG-monomethyl-L-arginine,
suggesting that vitamin D-induced NO production may play a role in the
host defense against human tuberculosis.
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
1,25-Dihydroxyvitamin D3 Induces Nitric
Oxide Synthase and Suppresses Growth of Mycobacterium
tuberculosis in a Human Macrophage-Like Cell Line
*
Corresponding author. Mailing address: University
Department of Paediatrics, John Radcliffe Hospital, Oxford OX3
9DU, United Kingdom. Phone: 1865-221061. Fax: 1865-220479. E-mail: krockett{at}hammer.imm.ox.ac.uk.
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