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1996-03-04
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Document 0707
DOCN M9640707
TI H2O2 induces monocyte apoptosis and reduces viability of Mycobacterium
avium-M. intracellulare within cultured human monocytes.
DT 9604
AU Laochumroonvorapong P; Paul S; Elkon KB; Kaplan G; Laboratory of
Cellular Physiology and Immunology, Rockefeller; University, New York,
New York, USA.
SO Infect Immun. 1996 Feb;64(2):452-9. Unique Identifier : AIDSLINE
MED/96145063
AB Mycobacterium avium-M. intracellulare, an intracellular parasite of
mononuclear phagocytes, rarely causes disease in immunocompetent
individuals. In contrast, in human immunodeficiency virus type
1-infected patients, M. avium-M. intracellulare can infect almost every
tissue and organ. This suggests that immunocompetent individuals have a
protective mechanism to control or prevent the infection. How
mycobacterial may be killed by the host immune response is unclear. We
have recently reported that induction of apoptosis of Mycobacterium
bovis BCG-infected macrophages with ATP4- was associated with killing of
the intracellular mycobacteria. In the present study, a long-term
culture of M. avium-M. intracellulare-infected monocytes was used to
further evaluate the interaction between M. avium-M. intracellulare and
primary human monocytes. In our system, M. avium-M. intracellulare
parasitized the human monocytes and appeared to replicate slowly over 14
days within the host cells. To examine the role of apoptotic mechanisms
in survival or death of intracellular mycobacteria, M. avium-M.
intracellulare-infected human monocytes were treated with a monoclonal
antibody to Fas receptor (APO-1/CD95) or with various concentrations of
H2O2. Although both of these exogenous agents induced monocyte
apoptosis, optimal killing (65% reduction in CFU) of intracellular M.
avium-M. intracellulare was observed only when M. avium-M.
intracellulare-infected cells were treated with 10 mM H2O2. Fas-induced
apoptosis did not affect M. avium-M. intracellulare viability. Our
results suggest that not all stimuli of monocyte apoptosis induce
killing of intracellular M. avium-M. intracellulare. Since release of
H2O2 following phagocytosis of mycobacteria has been documented,
H2O2-induced apoptotic death of M. avium-M. intracellulare-infected
monocytes and its association with killing of the intracellular bacilli
may be a physiological mechanism of host defense against M. avium-M.
intracellulare.
DE Acquired Immunodeficiency Syndrome/IMMUNOLOGY Antigens, CD95/PHYSIOLOGY
Apoptosis/*DRUG EFFECTS Cells, Cultured Cycloheximide/PHARMACOLOGY
DNA/METABOLISM Human Hydrogen Peroxide/*PHARMACOLOGY Monocytes/*DRUG
EFFECTS/MICROBIOLOGY Mycobacterium avium Complex/*DRUG EFFECTS/GROWTH &
DEVELOPMENT/ IMMUNOLOGY Mycobacterium avium-intracellulare
Infection/IMMUNOLOGY Nitric Oxide/PHYSIOLOGY Support, U.S. Gov't,
P.H.S. JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).