Cord factor
Encyclopedia
Cord factor refers to lipoarabinomannan, a molecule generated from trehalose dimycolate
by virulent strains of Mycobacterium tuberculosis
and closely related species. It is a surface glycolipid which blocks macrophage activation by IFN-γ, induces secretion of TNFα and causes Mycobacterium tuberculosis to form cords in vitro
. This is the main virulence factor for the mycobacterium tuberculosis that makes it resistance to anti-tuberculosis medications.
Technical Note
In vitro stimulation of macrophages
Purified cord factor was used to stimulate
either mouse RAW 264.7 cells or bone
marrow-derived macrophages. Cord factor
was suspended at a concentration of
1 mg/ml in isopropanol and sonicated in
a bath sonicator (model 3510; Branson Ultrasonic
Corporation) for 5 min. This suspension
was then incubated at 60°C for 10
min. and sonication repeated.
The resulting solution was layered onto
24-well tissue culture plates at the indicated
concentrations and incubated at 37°C
in order to ensure complete evaporation
of the solvent. Control wells were layered
with solvent without cord factor and incubated
at 37°C. To this layer of cord factor,
either RAW 264.7 cells or bone marrow-
derived macrophages were added at
a concentration of 106 cells in 100 μl of medium
and incubated at 37°C for 24 hours
before activation e.g. TNF-α production
was measured in the supernatant.
Alternatively, cord factor was suspended
at a concentration of 0.2 or 2 mg/ml in
hexane. Of the resulting solution 50 μl was
layered onto 96-well tissue culture plates
at the indicated concentrations of 1 or 10
μg/well, respectively and the solvent completely
evaporated.
Control wells were layered with solvent
without cord factor and incubated
at 37°C. To this layer of cord factor, either
RAW 264.7 cells or bone marrow-derived
macrophages were added at a concentration
of 106 cells in 100 μl of medium and
incubated at 37°C for 24 hours before activation
e.g. TNF-α production was measured
in the supernatant.
In vivo pulmonary granuloma
formation in mice
For in vivo experiments 10 μg cord factor
per mouse was applied i.v. in a water/
oil/water emulsion.
LIT: Interferon-gamma independent formation of pulmonary granuloma
in mice by injections with trehalose dimycolate (cord factor),
lipoarabinomannan and phosphatidylinositol mannosides isolated
from Mycobacterium tuberculosis: H. Takimoto, et al.; Clin. Exp. Immunol.
144, 134 (2006) Macrophage scavenger receptor downregulates
mycobacterial cord factor-induced proinflammatory cytokine
production by alveolar and hepatic macrophages: Y. Ozeki,
et al.; Microb. Pathog. 40, 171 (2006)
Trehalose dimycolate
Trehalose dimycolate is a molecule produced by Mycobacterium tuberculosis and other mycobacteria....
by virulent strains of Mycobacterium tuberculosis
Mycobacterium tuberculosis
Mycobacterium tuberculosis is a pathogenic bacterial species in the genus Mycobacterium and the causative agent of most cases of tuberculosis . First discovered in 1882 by Robert Koch, M...
and closely related species. It is a surface glycolipid which blocks macrophage activation by IFN-γ, induces secretion of TNFα and causes Mycobacterium tuberculosis to form cords in vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...
. This is the main virulence factor for the mycobacterium tuberculosis that makes it resistance to anti-tuberculosis medications.
See also
- NocardiaNocardiaNocardia is a genus of weakly staining Gram-positive, catalase-positive, rod-shaped bacteria. It forms partially acid-fast beaded branching filaments . It has a total of 85 species. Some species are non-pathogenic while others are responsible for nocardiosis. Nocardia are found worldwide in soil...
- Cording (mycobacterium)Cording (mycobacterium)Cording, in mycobacteriology, refers to a tendency of some mycobacterium to grow end to end, giving them a rope or cord-like appearance when viewed on a stained slide through a microscope. This growth pattern is due to cord factor, a glycolipid, and contributes to the virulence of the organism.-...
Technical Note
In vitro stimulation of macrophages
Purified cord factor was used to stimulate
either mouse RAW 264.7 cells or bone
marrow-derived macrophages. Cord factor
was suspended at a concentration of
1 mg/ml in isopropanol and sonicated in
a bath sonicator (model 3510; Branson Ultrasonic
Corporation) for 5 min. This suspension
was then incubated at 60°C for 10
min. and sonication repeated.
The resulting solution was layered onto
24-well tissue culture plates at the indicated
concentrations and incubated at 37°C
in order to ensure complete evaporation
of the solvent. Control wells were layered
with solvent without cord factor and incubated
at 37°C. To this layer of cord factor,
either RAW 264.7 cells or bone marrow-
derived macrophages were added at
a concentration of 106 cells in 100 μl of medium
and incubated at 37°C for 24 hours
before activation e.g. TNF-α production
was measured in the supernatant.
Alternatively, cord factor was suspended
at a concentration of 0.2 or 2 mg/ml in
hexane. Of the resulting solution 50 μl was
layered onto 96-well tissue culture plates
at the indicated concentrations of 1 or 10
μg/well, respectively and the solvent completely
evaporated.
Control wells were layered with solvent
without cord factor and incubated
at 37°C. To this layer of cord factor, either
RAW 264.7 cells or bone marrow-derived
macrophages were added at a concentration
of 106 cells in 100 μl of medium and
incubated at 37°C for 24 hours before activation
e.g. TNF-α production was measured
in the supernatant.
In vivo pulmonary granuloma
formation in mice
For in vivo experiments 10 μg cord factor
per mouse was applied i.v. in a water/
oil/water emulsion.
LIT: Interferon-gamma independent formation of pulmonary granuloma
in mice by injections with trehalose dimycolate (cord factor),
lipoarabinomannan and phosphatidylinositol mannosides isolated
from Mycobacterium tuberculosis: H. Takimoto, et al.; Clin. Exp. Immunol.
144, 134 (2006) Macrophage scavenger receptor downregulates
mycobacterial cord factor-induced proinflammatory cytokine
production by alveolar and hepatic macrophages: Y. Ozeki,
et al.; Microb. Pathog. 40, 171 (2006)