A Possible Clue To Surviving Hiv

Why do some people with HIV never develop AIDS? Scientists have long known that these lucky "long-term nonprogressors" secrete a protective substance from immune cells called CD8 T cells. But because these cells churn out thousands of proteins, identifying the AIDS fighters among them has proved daunting. Now the mystery may be solved. In the online version of the journal Science last week, Drs. David Ho and Linqi Zhang of New York's Aaron Diamond AIDS Research Center identified the elusive defenders as a group of three proteins called alpha-defensins. "This discovery is a major step forward in our understanding of how the body fights HIV," says Zhang.

The scientists owe their breakthrough to new technology that allowed them to sift quickly through vast numbers of proteins. They found that CD8 cells from nonprogressors manufactured one set of proteins that those of AIDS patients did not--the alpha-defensins. And further tests showed that the defensins were not just bystanders. The proteins kept HIV from replicating in cultures.

Other scientists are skeptical. Virologist Jay Levy of the University of California, San Francisco, insists that the alpha-defensins have only weak antiviral properties and says that in his experiments, CD8 cells don't even make the proteins. Only further research will resolve the dispute.

Whoever's right, the announcement will not yield new treatments soon. The proteins are too cumbersome to synthesize or inject. But unraveling the way they work could one day lead to new approaches to treatment--making every patient a potential nonprogressor.