Important note: Information in this article was accurate in May 2000. The state of the art may have changed since the publication date.
Several studies have found that infusing CD8+ cells into PHAs is generally safe. Results also show that the cells transferred during this process sometimes have anti-HIV activity. Unfortunately the transferred cells do not live long. In one study, about 90% of CD8+ cells died 48 hours after being infused. Researchers are conducting experiments to find out why this happens and to develop ways to extend the life of these CD8+ cells.
According to their latest series of experiments, researchers in Seattle reported infusing about one billion anti-HIV CD8+ cells into HIV-positive subjects. The cells quickly moved to the lymph nodes, which containing large amounts of HIV. Once there, the cells released anti-HIV chemicals.
In previous experiments, researchers found that infusions of anti-HIV CD8+ cells resulted in a temporary reduction of CD4+ cell levels. It is likely that the lost CD4+ cells had been infected with HIV and were killed by the CD8+ cells. As before, the infused CD8+ cells rapidly disappeared from the blood. Within two to three weeks of the infusion, most of the CD8+ cells could no longer be detected.
Future experiments will attempt to keep the infused cells alive for longer periods of time. One method may be to infuse both CD4+ and CD8+ cells together in the hope that, somehow, interaction between the two types of cells will help CD8+ cells live longer. Another research team thinks that infusing CD8+ cells together with another group of cells called dendritic cells may be a useful option.
According to some researchers, bathing CD8+ cells with the immune booster IL-2 (interleukin-2) prior to infusion may prolong their life. Other research suggests that treating CD8+ cells with the immune booster IL-12 (interleukin-12) before infusions may also help prolong their life but this needs to be confirmed.
Whatever the method, researchers are busy searching for a way to keep CD8+ alive or to identify HIV-fighting chemicals they produce so that therapies can one day be developed for PHAs.
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