Researchers have identified cells that halt the progression of HIV to AIDS. They studied people who have had HIV for years , yet never develop symptoms of AIDS. The findings could allow scientists to find an effective AIDS vaccine.
A small group of HIV infected people; referred to as long-term non-progressors (LTNPs) , have a special type of immunity that kills HIV when it infects the cells , known as CD8+ T cells. According to the new research , CD8+ T cells become highly effective HIV killers when they team up with other molecules in the body. When the molecules get together , they destroy HIV infected cells , halting the progression of HIV to AIDS.
Stephen Migueles , M.D. , senior author Mark Connors , M.D. , and colleagues at the National Institute of Allergy and Infectious Diseases (NIAID) , studied CD8+ T with innovative technology that allowed them to watch how CD8+ T cells , taken from long-term HIV survivors , kill HIV infected cells.
The researchers discovered that cells taken from LTNP’s destroyed HIV in less than an hour. Conversely , CD8+ T taken from AIDS progressors could not do the job , even when CD8+T cells were present in large quantities.
The second molecule , manufactured by CD8+ T cells is the protein , perforin. When enough perforin forms it punches holes in the HIV infected cells. The next molecular member of the HIV killing team , granzyme B , then enters the HIV infected cell , killing the virus.
The research clarifies how HIV survivors are able to avoid symptoms of AIDS. The accumulation of sufficient quantities of perforin and granzyme B in CD8+ T cells eliminates HIV in infected cells. The discovery explains why a minority of people infected with HIV do not require medications to stop the progression of HIV to AIDS.
The researchers hope for a new vaccine that can facilitate the production of large amounts of perforin and granzyme B from CD8+ T cells. If such a vaccine proves successful , it may provide a way to keep HIV infected individuals from developing AIDS.
Kathleen Blanchard , RN
http://grabsomehealthnews.blogspot.comSource:
http://www3.niaid.nih.gov/news/newsreleases/2008/LTNPs.htm
