Natural Antibody Shows
Promise as HIV Treatment
Excerpt By Merritt McKinney, Reuters Health Writer

NEW YORK (Reuters Health) - In a finding that could lead to new HIV therapies, scientists have identified a component of the ``innate'' immune system that the body uses to combat the virus.

The discovery may open the door to a new type of treatment for HIV, since it is possible to grow the component in the laboratory, one of the study's authors told Reuters Health in an interview.

Innate immunity is a relatively new area in the study of the body's immune system, according to Dr. Ronald Winston, president of both the Switzerland-based Institute for Human Genetics and Biochemistry and the Harry Winston Research Foundation in New York.

Most people are familiar with induced immunity, which is the immune response that occurs when the body recognizes an outside invader because it was exposed to it in the past. For instance, after having chickenpox, a person develops an induced immunity to the virus that causes the illness, which prevents repeat infections.

``The problem with the AIDS virus,'' according to Winston, is that ``it's constantly re-camouflaging itself with a new protein code.'' When the virus changes its camouflage, ``the body doesn't recognize it anymore,'' which makes developing a vaccine difficult, he explained.

But Winston and his colleagues, who were led by Dr. Toby C. Rodman of Rockefeller University in New York, discovered HIV-fighting antibodies of the body's innate immune system--the defenses that are functional without first being exposed to a virus or another outside invader.

These antibodies in the blood defend against HIV by reacting with certain parts of the virus, Winston explained. But eventually, as an HIV-positive person develops full-blown AIDS, he noted, the body stops producing large numbers of the antibodies.

``The body's immune system gets paralyzed,'' he said.

Winston and his colleagues suspect that a person with HIV starts to get sick as the body begins to lose its innate immunity to the virus. But the researchers speculate that if adequate levels of the antibodies could be restored, it might be possible to prevent HIV-related illness.

``We show a very specific therapeutic action'' of these antibodies, Rodman, the lead author, told Reuters Health in an interview. She explained that the antibodies inhibit an HIV protein called the Tat protein. The activity of the Tat protein causes some of the ``most disastrous'' effects of HIV, according to Rodman.

Since the antibodies block this deadly protein, ``they may be a source of therapeutic agents,'' she said.

After isolating the antibodies in human beings, the researchers were able to produce them in the lab. Using cells taken from umbilical-cord blood, the researchers grew the innate anti-HIV antibodies. The next step is to produce enough of the antibodies to test them as a treatment for HIV, Winston explained.

``We would like to talk to a bioengineering firm to figure out how to get this toward clinical trials,'' he said.

Winston stressed that the research, which appears in the August issue of the journal Experimental Hematology, is still in the early stages. Still, he said he believes the findings are exciting because any treatment based on such antibodies would be ``reintroducing what is natural and what is normally sustained'' in the body.

SOURCE: Experimental Hematology 2001;29:1004-1009.

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