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macrophage migration test 476 Madsen, Thorvald
macrophage migration test
An in vitro assay of cell-mediated immunity. Macrophages and
lymphocytes to be tested are placed into segments of capillary
tubes about the size of microhematocrit tubes and incubated in
tissue culture medium containing the soluble antigen of interest,
with maintenance of appropriate controls incubated in the
same medium not containing the antigen. Lymphocytes from
an animal or human sensitized to the antigen release a lymphokine
called migration inhibitory factor (MIF) that blocks
migration of macrophages from the end of the tube where the
cells form an aggregated mass. The macrophages in the control
preparation (which does not contain antigen) will migrate out
of the tube into a fan-like pattern.
macrophage–monocyte chemotaxis
Macrophages and monocytes are strongly adherent cells
and have a rate of locomotion slower than that of neutrophils.
They mount a chemotactic response to microorganisms,
formyl–Met–Leu–Phe, C5a, C5a des Arg, leukotriene
B 4, platelet-activating factor, thrombin, and elastin. Tumors
in humans and animals may produce an inhibitor that
causes monocytes or macrophages to migrate poorly in
chemotaxis assays.
macrophage–monocyte inhibitory factor (MIF)
A substance synthesized by T lymphocytes in response
to immunogenic challenge that inhibits the migration of
macrophages. MIF is a 25-kDa lymphokine. Its mechanism
of action is by elevating intracellular cAMP, polymerizing
microtubules and stopping macrophage migration. MIF
may increase the adhesive properties of macrophages,
thereby inhibiting their migration. The two types of the
protein MIF include one of 65 kDa with a pI of 3 to 4 and
another of 25 kDa with a pI of approximately 5.
macrophages
Mononuclear phagocytic cells derived from monocytes
in the blood that were produced by stem cells in the bone
marrow. These intensely phagocytic cells have a powerful
although nonspecific role in immune defense. They contain
lysosomes and exert microbicidal action against microbes
they ingest. They also have effective tumoricidal activity.
They may take up and degrade both protein and polysaccharide
antigens and present them to T lymphocytes in the
context of major histocompatibility complex (MHC) class
II molecules. They interact with both T and B lymphocytes
in immune reactions. They are frequently found in areas of
epithelium, mesothelium, and blood vessels. Macrophages
have been called adherent cells as they readily adhere to
and spread on glass and plastic and manifest chemotaxis.
They have receptors for Fc and C3b on their surfaces, stain
positively for nonspecific esterase and peroxidase, and
are Ia antigen-positive when acting as accessory cells that
present antigen to CD4 + lymphocytes in the generation of
an immune response. Monocytes that may differentiate into
macrophages when they migrate into the tissues comprise
3 to 5% of leukocytes in the peripheral blood. Tissuebound
macrophages may be found in the lung alveoli, as
microglial cells in the central nervous system, as Kupffer’s
cells in the liver, as Langerhans’ cells in the skin, and as
histiocytes in connective tissues, as well as macrophages
in lymph nodes and peritoneum. Multiple substances are
secreted by macrophages including complement components
C1 through C5, factors B and D, properdin, C3b
inactivators, and β-1H. They also produce monokines such
as interleukin-1 (IL1), acid hydrolase, proteases, lipases,
and numerous other substances.
macropinocytosis
Antigen uptake through engulfment by a cell of extracellular
fluid droplets containing soluble macromolecules and
creating macropinosomes that join the endocytic pathway.
Referred to also as cell drinking.
macropinosome
A structure produced by invagination of a plasma cell membrane
to produce a vesicle containing an extracellular fluid
droplet. Refer to macropinocytosis.
Naive T cell
L-selectin
MadCAM-1
Mucosal endothelium
MadCAM-1.
MadCAM-1
Mucosal addressin cell adhesion molecule-1; an addressin
in Peyer’s patches of mice. This three-immunoglobulin
domain structure with a polypeptide backbone binds the
α 4β7 integrin. The lymphocyte surface proteins L-selectin
and VLA-4 recognize MadCAM-1. MadCAM-1 facilitates
access of lymphocytes to the mucosal lymphoid tissues, as
in the gastrointestinal tract.
Madsen, Thorvald
Danish bacteriologist who, with Svante Arrhenius, a colleague
of Paul Ehrlich, formed an opinion that the reaction
of antibody and antigen was a reversible equilibrium
between the substances as when a weak acid and weak base
are combined according to the ordinary law of mass action.