Following bone marrow transplants, two men infected with HIV no longer have any traces of the AIDS-causing virus in their lymphocytes, researchers report.
Lymphocytes are a type of white blood cell and are a key part of the immune system.
The U.S. researchers suspect that bone marrow transplantation along with continuation ofantiretroviral therapy resulted in the dramatic effects evident eight months post-transplant. They are scheduled to present these preliminary findings Thursday at the International AIDS Conference in Washington, D.C.
HIV patients on antiretroviral therapy often achieve "undetectable viral loads," meaning there are no virus particles in their blood. But they still have latent HIV in their lymphocytes, and if antiretroviral therapy were discontinued, the latent HIV could reactivate.
But having no traces of HIV in these white blood cells is an indication that this "reservoir" of latent HIV may have been eliminated, the researchers believe.
At this point, they are far from saying these patients are cured. But the findings are "exciting," said Dr. Savita Pahwa, director of the Center for AIDS Research at the University of Miami Miller School of Medicine, who was not involved with the study.
"Every hint you get that it’s possible to wipe out the reservoir needs to be investigated," she said.
"Eliminating the reservoir is the key to the cure," said Pahwa. She also stressed that it would only be possible to say these patients were "functionally cured" if the virus did not rebound when the patients went off antiretroviral therapy.
The two men whose cases are described in the paper underwent chemotherapy for blood cancers before receiving stem cell transplants. One had his transplant two years ago; the other, four years ago. Both also developed graft-versus-host disease (when transplanted cells attack the host cells) and continued with their antiretroviral medications throughout and after the transplant procedures.
Any of these factors could theoretically explain their HIV-free status, but the bone marrow transplantation combined with antiretroviral therapy seems the most likely explanation, said the study authors.