Important note: Information in this article was accurate in 1995. The state of the art may have changed since the publication date.

Reuters NewMedia, Inc. - 6 Dec 1995
Joanne Kenen / Reuter

The discovery of these natural "suppressors," reported in two prestigious research journals in Britain and the United States, does not have any immediate impact on AIDS patients. But scientists regard the discoveries as hugely significant and expect them to shed light on the body's peculiar responses to the HIV virus that causes AIDS and to spur new lines of research into possible drugs or even a vaccine.

"The potential implications are substantial," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland.

"These papers are important in that they identify for the first time more than one factor...that is responsible for the blocking of HIV replication. This opens up new avenues of approach," Fauci told Reuters.

Both reports deal with factors produced by CD8 T cells, white blood cells that are components of the immune system.

In one, released ahead of publication next week in the journal Science, a U.S.-Italian team found three substances made by CD8 cells that were previously known to respond to inflammation but were not known to react to viruses.

"This was a surprise -- they had never been thought of as anti-virals," lead author Robert Gallo, the co-discoverer of HIV, told Reuters. "These are a naturally occurring set of molecules that inhibit HIV infection and replication."

In test-tube experiments on cell cultures, the substances shut down production of many strains of HIV and a related monkey virus.

In another study in the journal Nature, Reinhard Kurth and colleagues at the Paul-Ehrlich-Institut in Langen, Germany said they had found that interleukin-16 (IL-16), another substance secreted by CD8 cells, acted as a natural defense by slowing the reproduction of HIV viruses.

This happened at the highest rate after people were infected with HIV but before they showed AIDS symptoms.

Kurth said that, if animal tests are encouraging, he hopes to start human trials in about a year. He hopes IL-16 used with other drugs may help reduce the amount of virus in the body and so prolong the time patients stay symptom-free.

"If we manage to reduce the daily multiplication of viral cells from 100 million to one million, that would be a big step," he said.

Fauci said interleukin might eventually be used as an immune system booster -- similar to gamma globulin, which is given to people to boost their immune systems against forms of hepatitis. Not quite a vaccine, it works in a similar way.

The German team said African green monkeys, which often carry their own version of the virus, never contract the ape and monkey version of AIDS. Their interleukin-16 is similar to the human one, which might explain this protection.

AIDS researchers said scientists have known for some time that something unidentified in the "suppressor" T-cells was inhibiting the replication of the virus. Research is under way to find the basic mechanisms of how these various suppressor factors work, and that will then lead to animal studies to learn more about them, scientists said.

Two studies in this Thursday's New England Journal of Medicine report that an experimental drug that gums up the operation of a key protein used by the AIDS virus seems to keep it at bay for a while.

The drug is ritonavir, formerly known as ABT-538 and developed by Abbott Laboratories, which announcedMonday that it will make the experimental drug available via lottery to 2,000 people worldwide with advanced AIDS.

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