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Being Alive
ICA9 Report: Pathogenesis
Mark Katz, MD and reported by Jim Stoecker
July 5, 1993
Being Alive 1993 Jul 5: 4

We have known for some time now the general course of HIV in the body. Right after infection, the virus builds up in the body. The body then mounts its immune response and the viral load goes down. The viral load may stay down for some time. At some point, however, the virus begins to build up as the immune response weakens.

In looking at this process, researchers have begun to focus on the early stage of HIV infection. When designing strategies to enhance the immune system, it makes sense to zero in on the early phase because that is when the immune system is still reasonably intact. The body is still able to mount an immune response.

In past years, many immune boosters have been tested and rejected. But these were studied with people with advanced HIV disease. Now researchers are resurrecting some of these approaches in hopes that using these boosters earlier in the course of disease may bring greater success.

Jay Levy of San Francisco continues his research on the role of CD8 (T8 or T-suppressor) cells in fighting HIV progression. CD8 cells appear to secrete some factor that helps to hold HIV in check. This factor, however, has not yet been isolated. If we could isolate it and then genetically engineer it, CD8 factor might prove to be the most effective immune booster of all.

Levy also postulates that there are two kinds of CD4 cells: TH1 and TH2. Early in HIV disease, TH1 type T-cells predominate. These cells secrete cytokines (especially IL-2) which promote CD8 functioning. CD8 is then stimulated to produce the factor that fights HIV. At some point, however, TH2 cells begin to predominate. These cells secrete other cytokines (such as IL-10) which stop the TH1 cells and thus slows down the CD8 factor. HIV disease progression then begins to accelerate.

All in all, our understanding of the progression of HIV disease is growing. And from this, we hope to learn when and where to intervene for optimal effect. 

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