Researchers Discover how Natural Immunity Kills HIV Infected Cells

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