Doctors have boosted the immune systems of long-term HIV patients with a new therapy designed to protect them from common but potentially lethal infections.
The treatment doubled the number of immune cells HIV patients had circulating in their blood, suggesting it was rebuilding their ailing immune systems.
Infection with HIV wipes out immune cells and ultimately leads to the collapse of the entire immune system, leaving patients vulnerable to even minor infections.
In the developing world, a major cause of death among HIV sufferers is tuberculosis and pneumonia because their immune systems are too weak to fight the infections.
Doctors at the Gladstone Institute of Virology and Immunology, and the University of California, San Francisco, injected HIV patients with a growth hormone and found it kick-started the thymus, a gland which often shuts down after HIV infection. The thymus plays a crucial role in the body's defences by producing T cells, the workhorses of the immune system.
The study, published in the Journal of Clinical Investigation, is the first to show how a drug therapy can reactivate the thymus and immune system.
Laura Napolitano, who led the study, enrolled 22 HIV patients who had received standard HIV therapy for an average of three years. The patients were split into two groups, one being given regular injections of growth hormone, while the others continued therapy as before. At the end of the first year, the groups were swapped.
Blood samples and medical scans were used to check how well the patients responded throughout the treatment. The team found that when patients were given growth hormone, their thymus increased in size and produced twice as many fresh T cells. The increase persisted for at least one year after the injections were stopped.
Napolitano said the findings were proof of principle that the therapy could reverse damage caused by HIV, "an important step to determine whether immune therapies might someday benefit patients who need more T cells".
Though the trial was successful, the researchers said it was too early to consider growth hormone as a general treatment. The hormone is known to have side-effects, including a higher risk of diabetes, bone pain, swelling of the arms and legs, abnormal bone growth and carpal tunnel syndrome.
According to the World Health Organisation, 13 million people living with HIV are at risk of developing TB because their immune systems are unable to fight it. In some regions of Africa, up to 80% of adult TB patients are also infected with HIV.
Frances Gotch, an HIV specialist at Chelsea and Westminster hospital in London, said hormone therapy might help some patients, but added that treatment must first focus on reducing the amount of virus circulating in their blood.
