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Q: macrophages ( Answered 5 out of 5 stars,   0 Comments )
Subject: macrophages
Category: Science > Biology
Asked by: arti-ga
List Price: $10.00
Posted: 09 Sep 2003 08:08 PDT
Expires: 09 Oct 2003 08:08 PDT
Question ID: 253836
I am not researcher but I would like to know (in simple terms) what
scientific research protocols, procedures, assays, etc should or could
be done to detect macrophages as a result of infection, more
importantly, foreign particulates in the body.  Any addiiional
information you can supply would be greatly appreciated.
Subject: Re: macrophages
Answered By: hlabadie-ga on 10 Sep 2003 21:46 PDT
Rated:5 out of 5 stars
Macrophage is another term for a member of the more familiar
phagocytes, leukocytes or white blood cells that engulf and destroy
invading infectious agents such as bacteria. The word comes from the
Greek, macros, long, and phagein, to eat, from their ability to
surround large (relatively speaking) antigens.

MACROPHAGE - Definition by Hyper Dictionary

"Definition:   A type of large leukocyte that travels in the blood but
can leave the bloodstream and enter tissue; like other leukocytes, it
protects the body by digesting debris and foreign cells."

As such, macrophages can be detected most simply by the basic Complete
Blood Count (CBC), a microscopic test that physically counts the
number of white blood cells in a standard volume of blood. An
increased or elevated white blood cell count indicates infection, as
the body produces more leukocytes to attack the infection.

LAB RESULTS, Part 1: Complete Blood Count (CBC)

"Monocytes or Macrophages (Monos) make up 2% to 8% of WBCs. They fight
infections by "eating" germs and telling the immune system what germs
they have found. Monocytes circulate in the blood. When monocytes
settle in various tissues they are called macrophages. A high count
usually indicates a bacterial infection."

A more complex test that can indicate the presence of macrophages is
an immunohistochemical reactivity test, which looks for marker
chemicals that are produced as macrophages (and other cells) are
activated. As the name implies, the immune or allergic histamine
response results in the release of chemicals that in elevated amounts
will indicate infection or allergic reaction. One useful test looks
for induced nitric oxide synthase (iNOS). Macrophages produce nitric
oxide in a chemical reaction that is mediated by the enzyme iNOS.
Because nitric oxide vanishes from the blood too quickly to be
measured directly (half life of about 5 seconds), a test for iNOS is
conducted as an indirect measure of induced nitric oxide production.

Section 19.3 — Probes for Nitric Oxide Research

"Nitric oxide (NO), the molecule that makes the firefly glow,[ref]
plays a critical role as a molecular mediator of a variety of
physiological processes, including blood-pressure regulation and
neurotransmission.[ref] In endothelial cells, as well as neurons and
astrocytes, NO is synthesized from L-arginine in a reaction catalyzed
by nitric oxide synthase [ref] (NOS) (Figure 19.13). NO that diffuses
into smooth muscle cells binds to the heme group of guanylate cyclase.
Because free NO is a transient species with a half-life of about five
seconds, many investigations of this gaseous molecule have relied
largely on studies of NOS."
"NO can also complex with superoxide to form the strong oxidant,
peroxynitrite anion [ref] (ONOO–, Table 19.1), which may be a major
cytotoxic agent produced during inflammation, sepsis and
ischemia/reperfusion.[ref] Activated macrophage and neutrophils
produce nitric oxide and superoxide, and thus peroxynitrite anion, at
similar rates."

Nitric oxide and infectious diseases

"In contrast, inducible NOS (iNOS or NOS2) is absent in resting cells,
but the gene is rapidly expressed in response to stimuli such as
proinflammatory cytokines. Once present, iNOS synthesises 100–1000
times more NO than the constitutive enzymes and does so for prolonged

The quantity of nitric oxide released by macrophages regulates
Chlamydia-induced disease

"Analysis of NO Production. To analyze the immunosuppressive
mechanism, we evaluated total serum nitritenitrate as an indicator of
cumulative NO production. Macrophage-released NO synthesized by NOS2,
the high output NOS isoenzyme, acts as a regulator of lymphocyte
growth and is immunosuppressive through the induction of apoptosis in
activated T cells (15)."
"NOS2 expression in Chlamydia-infected lung tissue was examined by
immunohistochemical staining. Lesions in infected lungs (Fig. 4, which
is published as supporting information on the PNAS web site, were either double-stained (cryo-sections) or serial
sections single-stained (formalin-fixed sec-tions) with antibodies
against C. psittaci, NOS2, or the macrophage maturation marker

See also:

Coinduction of Nitric Oxide Synthase, Argininosuccinate Synthetase,
and Argininosuccinate Lyase in Lipopolysaccharide-treated Rats

Lipid Vesicle Size Determines the Th1 or Th2 Response to Entrapped

"The ability to phagocytose large particles is one of the features
that distinguishes macrophages from other APCs (37, 38), although some
capacity for ingestion of particulate Ags has been demonstrated for
dendritic cell progenitors in vitro (39, 40). In contrast, other APCs,
such as B lymphocytes, cannot phagocytose (37, 38) and must presumably
ingest Ag by pinocytic mechanisms, which effectively means they cannot
internalize particles greater than approximately 150 nm (35, 36)."

In cases of particulate induced infections, magnetic resonance imaging
(MRI) or transmission electron microscopy (TEM) or scanning electron
microscopy (SEM) sometimes can be used successfully. Naturally, the
type of particulate will determine which is appropriate.

Magnetic Resonance Imaging of Atherosclerotic Plaque With Ultrasmall
Superparamagnetic Particles of Iron Oxide in Hyperlipidemic Rabbits

Based on the observation that ultrasmall superparamagnetic particles
of iron oxides (USPIOs) are phagocytosed by cells of the mononuclear
phagocytic system, the purpose of this study was to evaluate their use
as a marker of atherosclerosis-associated inflammatory changes in the
vessel wall before luminal narrowing is present."
"Conclusions—USPIOs are phagocytosed by macrophages in atherosclerotic
plaques of the aortic wall of hyperlipidemic rabbits in a quantity
sufficient to cause susceptibility effects detectable by MRI."


"Particle phagocytosis plays a key role in macrophage activation and
hence the size of the particle is significant. Histologic observations
of tissues around failed total joint replacements frequently note an
abundance of enlarged macrophages, often with visible particles within
their cytoplasm."
(Contains microscopic slides of engulfed particles.)



Request for Answer Clarification by arti-ga on 11 Sep 2003 08:07 PDT
If the phagocytic activity is in response to the wear particles
(referred to in Chapter 13 cited below in your answer) what is the
best means of detection when using a tissue sample?

Clarification of Answer by hlabadie-ga on 11 Sep 2003 12:11 PDT
The .pdf suggests that the presence of the particles can be detected
using the immunohistochemical tests for the various interleukins
(cytokines), abbreviated IL, and the tumor necrosis factor (TNF). The
actual paricles themselves can be viewed usually only by scanning
electron microscopes or transmission electron microscopes, due to
their extraordinarily small sizes.
From the .pdf:
"It became apparent that the majority of wear particles in the tissues
were submicron to nanometer in size (Figs. 5 and 6), below the level
of resolution of most light microscopes."
"the in vitro response of murine peritoneal macrophages to
polyethylene particles of definitive size distribuitons (mean sizes of
0.21, 0.49,  4.3, 7.2, and 88 micrometers) was measured by IL-6, IL-B,
and TNF-a production."

For some information on the interleukins, see:

Interferon- g and interleukin-4 production of ovalbumin-stimulated
lymphocytes in
egg-sensitive children

Thanks for the rating and the tip.

arti-ga rated this answer:5 out of 5 stars and gave an additional tip of: $2.00
The answer you supplied gave me clarificatio to ask the questio I
really needed to ask from the start.  I posted clarification in order
to further progress to the answer needed.  Thank you "hlabadie-ga"!

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