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A tiny minority of people, about one
in 300, can keep HIV from progressing to AIDS without drugs. In such “elite
controllers,” the virus is kept in check with “killer” cytotoxic T lymphocyte
cells, earlier research has shown. In a new study, investigators found that
elite controllers differ from others with HIV in how well these killer cells
work, not in how many cells they have. In particular, the effective strain has
receptors that are better able to identify HIV-infected white blood cells for
attack.
People with HIV “have tons of these
killer cells,” said Bruce Walker, an infectious-diseases expert at the Ragon
Institute in Massachusetts. “We have been scratching our heads since then,
asking how, with so many killer cells around, people are getting AIDS. It turns
out there is a special quality that makes [some cells] better at killing.”
Walker and colleagues examined 10
people with HIV: five who took antiretroviral therapy to control the virus, and
five elite controllers who were naturally healthy.
“What we found was that the way the
killer cells are able to see infected cells and engage them was different,”
Walker said. “It is not just that you need a killer cell, what you need is a
killer cell with a [T cell] receptor that is particularly good at recognizing
the infected cell. This gives us a way to understand what it is that makes a
really good killer cell.”
Generating such cells, however,
remains problematic for researchers. “The next step is to determine what it is
about those receptors that is endowing them with that ability,” said Walker.
“Each secret that HIV reveals is putting us in a better position to ultimately
make a vaccine to control the virus.”
[PNU editor’s note: The study, “TCR
Clonotypes Modulate the Protective Effect of HLA Class I Molecules in HIV-1
Infection,” was published in Nature Immunology (2012;doi:10.1038/ni.2342).]
The Friends of AIDS Foundation is
dedicated to enhancing the quality of life for HIV positive individuals and
empowering people to make healthy choices to prevent the spread of the HIV
virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.
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