December 17, 2009
Body Might Eliminate Best Weapon Against HIV
It turns out the human body can produce very potent antibodies to help fight HIV—but it eliminates them before they fully mature, according a study published online December 14 in the Proceedings of the National Academy of Sciences and reported by ScienceDaily.
Antibodies are one of the most important components of the immune system to fight diseases. Not only can antibodies bind to and tag infectious organisms for elimination by other immune cells, they can sometimes kill those organisms directly. For many years, scientists believed HIV was able to elude such an attack by hiding its most vulnerable parts.
Several years ago, however, researchers at Duke University in Durham, North Carolina, hypothesized the body might recognize the most potent anti-HIV antibodies as a threat and eliminate them. They wondered whether this is because these more potent antibodies resemble too closely the type of antibodies that betray and attack our own bodies. This process is called autoimmunity and is characteristic of diseases like lupus and rheumatoid arthritis.
To determine whether this was occurring, Laurent Verkoczy, PhD, and his colleagues from Duke University genetically engineered mice that could produce only B cells—immune cells that make antibodies—capable of generating a potent antibody against HIV.
Verkoczy’s team found that the mice could make immature forms of the B cells, but their bodies eliminated them before they could become mature and effective.
“We have now unveiled a major reason why members of this class of neutralizing antibodies are not routinely made: Our own immune systems block their production because they are perceived as potentially harmful, when in reality, they are not,” said Barton Haynes, PhD, the team’s senior member. “This is a very unusual way the virus has developed to evade the immune system.”
The team also found, however, that about 15 percent of those B cells did survive but were circulating in the body in a deactivated state. Researchers viewed this discovery as encouraging news. Verkoczy explained: “One goal in vaccine design may be to figure out how to wake them up so they can go to work.”
Search: B-cells, antibodies, autoimmunity, Duke, Laurent Verkoczy, Barton Haynes
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