News and Research
Immune System
New Role For Immune System Player May Help Improve Cancer
Vaccines
11-1-2002
Researchers have discovered that a molecule best known for
its anti-microbial properties also has the ability to activate
key cells in the immune response. This newly discovered
function, reported in the Nov. 1, 2002, issue of Science,
suggests the molecule, a peptide called ß-defensin
2, may be useful in the development of more effective cancer
vaccines. Scientists have found that ß-defensin 2
initiates a chain of events leading to the growth and multiplication
of T cells, components of the immune system that recognize
and kill foreign cells that have invaded the body.
Defensins
are known to be an important component of the body's immediate
response to infection. ß-defensin 2 attacks and destroys
a broad range of bacteria as part of the innate immune system,
the body's first line of defense against such infections.
The
new finding links ß-defensin 2 to the second arm of
the immune system, adaptive immunity. The adaptive immune
response combats pathogens that evade the body's initial
defense mechanisms. Unlike innate immunity, the adaptive
immune system develops specifically in response to an infection,
changing as needed to ward off each invader.
"This
link between the innate and adaptive immune systems is important
for our understanding of the body's ability to detect infection,"
said Arya Biragyn, Ph.D., National Cancer Institute (NCI)
staff scientist and first author of the study. "ß-defensin
2 is likely to play an important role in the immune system's
ability to recognize protein fragments from the body's own
cells, including tumor cells."
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Working in both mice and laboratory cell cultures,
Biragyn and his colleagues found that ß-defensin 2 directly
activates immune cells known as dendritic cells. Once activated, dendritic
cells interact with other components of the immune system to stimulate
the multiplication of a subset of T cells that will recognize and
destroy infected cells. Dendritic cells can also trigger attack of
tumor cells by the immune system.
"When we administered ß-defensin 2 to mice,
we observed a robust response among cells involved in anti-tumor immunity,"
noted NCI's Larry W. Kwak, M.D., Ph.D., the senior investigator on
the study. Researchers hope to take advantage of this property by
incorporating ß-defensin 2 into cancer vaccines.
Cancer vaccines are an investigational therapy designed
to program the body's own immune system to attack a tumor. The vaccine
does this by training T cells to recognize cancerous cells. Scientists
hope that adding ß-defensin 2 to such vaccines will promote
the growth and multiplication of the tumor-destroying cells, improving
patient response to the therapy.
Similarly, researchers hope that ß-defensin
2 will also be useful in improving AIDS vaccines in the future.
For more information on cancer, please visit NCI's
Web site at www.cancer.gov.
This
article has been adapted from a news release issued by NIH/National
Cancer Institute, www.nci.nih.gov.
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