Published on August 20, 2006 at 9:41 PM
It appeared that HIV turned the T cell switch off, triggering the inhibitory PD-1 pathway and this in turn was associated with more severe functional impairment of T cells.
When HIV treatment began, however, blocking the PD-1 pathway, the T cell function was restored.
The researchers say the next step will be to see if the T cells can be turned back on in HIV-infected people in a way that will benefit them without incurring any serious side effects.
They are also exploring whether PD-1 measurements could be used to guide treatment.
Dr Walker, a professor of Medicine at Harvard Medical School and a Howard Hughes Medical Institute investigator, says at present to decide when to treat someone, the number of T cells is counted, but the possibility that adding PD-1 measurement might give more information about the likely progression of the disease and need for treatment in infected people, is he says exciting.
Experts and specialist in HIV and AIDS say the study is promising and encouraging, and fills another gap in scientists' knowledge about how HIV functions.
They hope that it will lead to new therapies to treat and prevent the disease within the coming decade.
The study is published in the journal Nature.