Georgetown researcher links increase in key T cells caused by anti-HIV therapy to T cells traveling through lymph nodes

(Washington, DC) - A Georgetown University Medical Center researcher has found that a certain type of CD4+ T cell-a type which travels through the lymph nodes-increases in HIV patients after they receive antiretroviral (anti-HIV) therapy. These findings are published in the July 1 issue of the Journal of Infectious Diseases.

"We've known for some time that CD4+ T cells increase after HIV patients receive anti-HIV drug combinations," said Richard Hengel, MD, assistant professor of medicine at Georgetown University Medical Center and the lead author of this study. "What this study shows us is that it is a specific type of CD4+ T cell that is primarily responsible for this increase-the CD4+ T cells which traffic through the lymph nodes." Hengel added that this finding might have important implications for the pathogenesis of HIV and for future HIV vaccine development.

It is in the lymph nodes that immune responses to infection begin, causing increases in infection-fighting cells. The lymph node-travelling CD4+ T cells are preferentially depleted during HIV infection, but this study shows that antiretroviral therapy causes their reaccummulation for at least one year.

"This study helps us better understand how HIV causes depletion of CD4+ T cells, as well as how the antiretroviral drugs help the immune system recover," Hengel said. "The findings may help explain why HIV patients typically show increased immunity to opportunistic infections after receiving antiretroviral therapy, even before total numbers of CD4+ T cells have risen dramatically; it may be due to the fact that lymph node recirculating CD4+ T cells are the most important cells for eliciting a robust immune response."

CD4+ T cells are targets for HIV infection. Depletion of these cells-whether due to HIV or to other types of infection-leads to suppression of the immune system, and to increased risk of developing opportunistic infections. The CD4 cell count is the most commonly used marker for assessing the state of the immune system.

This study, which was funded by and conducted at the Centers for Disease Control and Prevention (CDC) in Atlanta, Ga., involved 20 HIV-infected patients who received antiretroviral therapy over the course of one year.

Although he is now a faculty member at Georgetown University Medical Center, Hengel conducted the research for his study while a fellow at Emory University School of Medicine and CDC. In addition to Hengel, the research team included J. Steven McDougal, Bonnie M. Jones, M. Susan Kennedy and Marjorie R. Hubbard, all of the CDC.

The full article is available on-line at www.journals.uchicago.edu/JID.

For more information, or to arrange an interview with Dr. Hengel, please contact Amy DeMaria at 202-687-5100 or at [email protected].

Georgetown University Medical Center includes the nationally ranked School of Medicine, School of Nursing and Health Studies, and a biomedical research enterprise. For more information, please visit www.georgetown.edu/gumc.