Are Some People Immune to AIDS?

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One of the most surprising findings has been the discovery of a subset of healthy, long-term survivors who have lived for years with CD4 counts less than 200. For the most part, they do not develop the secondary infections that are associated with AIDS, or if they do, they tend to recover. This only goes to prove that there is a lot about the immune system that immunologists still do not understand. Some researchers believe these men managed to press other white blood cells into service to make up for the CD4 deficiency.

Because gay men were the first people to be studied, most of the current data comes from them. In the past 18 months, however, researchers have launched a growing number of studies of women and children infected with HIV, and the preliminary results are encouraging. Once investigators start looking for healthy survivors, they find them. Still the question remains -- Why? Does the amount of virus a woman is exposed to make a difference? How effective might her vaginal and cervical tissue be as a barrier against infection? Does it matter if a child is infected while still in the womb or during passage through the birth canal?

The answers to these and other questions are just beginning to take shape. By painstakingly studying the same individuals over long periods of time, scientists are changing the way they think about AIDS. Clearly, some people can fight off the virus on their own. Over the past five years, doctors have developed more and more treatments to control the opportunistic infections and illnesses that appear in other patients. Scientists may not discover a cure, but if they learn how to control an HIV infection the way diabetes can be managed with insulin, they will have tamed one of the most feared killers of the 20th century.