Agence France Presse (10.12.11) - Wednesday, October 26, 2011
While researchers have long known that vitamin D is involved
in the body's response to TB, a new study shows it must be
present at sufficient levels to trigger the immune response.
"Over the centuries, vitamin D has intrinsically been used to
treat tuberculosis," said lead author Mario Fabri.
"Sanatoriums dedicated to tuberculosis patients were
traditionally placed in sunny locations that seemed to help
patients, but no one knew why this worked."
"Our findings suggest that increasing vitamin D levels through
supplementation may improve the immune response to infections
such as tuberculosis," said Fabri, who conducted the research
while at the University of California-Los Angeles, and who now
is at the Department of Dermatology at the University of
Previously, the same research team showed that vitamin D plays
an important role in the production of cathelicidin, a
molecule that helps the innate immune system kill TB bacteria.
The new study shows that vitamin D is needed for the T-cells
in the adaptive immune system to produce the protein
interferon, which directs cells to attack the bacteria.
The finding could bolster TB treatment efforts in settings
like Africa, as dark-skinned people are more likely to be
deficient in vitamin D. This is because dark skin contains
more melanin, which shields the body from ultraviolet rays and
reduces vitamin D production.
"At a time when drug-resistant forms of tuberculosis are
emerging, understanding how to enhance natural innate and
acquired immunity through vitamin D may be very helpful," said
Barry Bloom, former dean of faculty at the Harvard School of
Public Health and a study co-author.
The report, "Vitamin D Is Required for IFN-gamma-Mediated
Antimicrobial Activity of Human Macrophages," was published in
Science Translational Medicine (10.12.11;3(104):104ra102).