Researchers at the Partners AIDS Research Center at Massachusetts General Hospital report that they have uncovered a mechanism that suppresses the immune system’s ability to control HIV, possibly resulting in a new target for HIV treatment.
The research team, led by Bruce Walker, MD, investigated the role of a protein called CTLA-4, a known suppressor of immune system activity. They found disproportionately high levels of CTLA-4 on HIV-specific CD4 cells—T cells designated to respond specifically to HIV in people infected with the virus. Levels were highest in people with more advanced HIV disease and lowest in a group of people, known as “elite controllers,” whose immune systems have a natural ability to keep the virus under control.
Of particular interest, antiretroviral treatment had only a minor effect on CTLA-4 levels. Even when treatment resulted in viral load reductions, drops in CTLA-4 levels were minimal and slow to occur. Dr. Walker says that further research is needed to validate these findings, but that “understanding why the immune system fails to control HIV is essential for development of vaccines and new therapies.”
