Are Some People Immune to AIDS?

ANYONE WHO THINKS THAT BEING infected with HIV amounts to an automatic death sentence should talk to Rob Anderson. The 39-year-old San Francisco artist has beaten the odds against him by living -- no, thriving -- with the virus that causes AIDS for 14 years. At 6 ft. 2 in. and 170 lbs., Anderson has only routine medical complaints: the stuffiness of an occasional head cold or the aches and pains of a flu. His good health is not the work of some miracle drug: he has never taken AZT or any other compound to fight HIV. Incredible as it sounds, Anderson's own immune system seems to have held the villainous virus at bay. "It feels good to be on the winning side of HIV," he says. Looking to the future with surprisingly little fear, he hopes to fix up the crumbling Victorian house that he shares with his HIV-negative companion of 10 years.

Does Anderson have a natural immunity to AIDS? Just a few years ago, the idea would have seemed absurd. But that was before the results started coming in from a group of long-term health studies of 10,000 gay men, begun in the late 1970s to mid-1980s. Scientists, prodded by AIDS activists who wanted to "study the healthy" and to lift the shadows of doom that surround the disease, have now documented at least 70 cases like Anderson's. Researchers are also beginning to find similarly healthy, long-lived survivors among women and children with HIV. There is now good reason to hope that at least 5% of the estimated 1 million Americans infected with the virus may never come down with the disease.

It sounds like the most morbid of questions to ask of a patient: "Why aren't you dead yet -- or even sick?" Looking for the answers may prove to be one of the most productive avenues of research in the battle against AIDS. By shifting their focus to the healthy, many researchers believe they can make dramatic improvements in the treatment of everyone who is infected with HIV -- whether ailing or not. Just as important, their work could channel the scattershot search for a vaccine into new and more promising directions. "Early in the epidemic we thought everyone who got infected died," says Dr. Lewis Schrager of the National Institutes of Health. "And that still may be true. But I'm becoming convinced that there is something about these people who are not progressing to AIDS that is worth intensive investigation."

Resistance to HIV does not seem to be the same as more common examples of immunity. The body's protective countermeasures against measles and mumps are absolute. Years after exposure, there is no hint within the body of the foreign agents that cause those diseases. After children become immune to mumps, they can no longer infect other people.

! That is not the case for healthy HIV survivors, no matter how wholesome their glow. They test positive for antibodies to HIV and small amounts of virus can be detected in their blood. Although stable, their immune systems show telltale signs of having been weakened by the infection -- not enough to make them sick but enough to register on blood tests. "We don't know how infectious these people are," says Dr. Susan Buchbinder of the San Francisco Department of Public Health. "But we have to assume that they can pass on the virus."