GayBombay: Why HIV patients are vulnerable to TB

Why HIV patients are vulnerable to TB

1 Jul 2009, 1236 hrs IST, ANI

Ending one of the biggest mysteries, Harvard scientists have found out why HIV patients are more susceptible to tuberculosis

(TB) infection.

In their study paper, a team of researchers led by Dr. Naimish Patel have described how HIV switches off the immune response to Mycobacterium tuberculosis.

The researchers have detailed how HIV interferes with the cellular and molecular mechanisms used by the lungs to fight TB infection.

With this discovery, the researchers have taken an important first step toward the development of new treatments to help people with HIV to prevent or recover from TB infection.

"HIV/TB co-infection is a critical global health problem, especially in developing countries. We hope that these findings will lead to further studies and possible new therapies for treating or preventing tuberculosis in HIV disease," said Patel.

For their study, the researchers extracted immune cells called "alveolar macrophages" from the lungs of otherwise healthy, asymptomatic HIV-positive patients as well as from people who did not have HIV.

In people who are HIV-positive, the macrophages have a decreased response to the TB bacterium when compared to people who did not have HIV.

To know why this happens, the scientists examined lung specimens from the HIV-positive patients, and found increased levels of a molecule called IL-10.

IL-10 elevated the amount of a protein called "BCL-3" in alveolar macrophages, which in turn reduced their ability to ward off TB infection.

"HIV and TB represent two of the most significant health challenges in human history and the combination of the two infections is particularly devastating because HIV dramatically increases the severity of TB infection," said Dr. John Wherry, Deputy Editor of the Journal of Leukocyte Biology,

He added: "There are still many unknowns about how HIV reduces the ability of the body to combat other infections. This study sheds light on co-infection with HIV and TB, which up to this point, has perplexed scientists and physicians alike."

The study has been published in the Journal of Leukocyte Biology.