Clinical

HIV infection impairs immune response to hepatitis C virus

Last Updated: 2006-12-22 13:40:13 -0400 (Reuters Health)

By Will Boggs, MD

NEW YORK (Reuters Health) - HIV infection impairs the hepatitis C virus (HCV)-specific T cell response, according to a report in the December issue of PLoS Medicine.

"The loss of HCV-specific immunity that is associated with HIV may have clinical consequences, namely a susceptibility to recurrent HCV viremia with potentially high viral loads," Dr. Arthur Y. Kim from Massachusetts General Hospital, Harvard Medical School, Boston, told Reuters Health. "This helps to explain the increased rate of HCV persistence seen in HIV coinfection."

Dr. Kim and associates investigated the effects of HIV-induced T cell depletion on T cell responsiveness to both HIV-1 and HCV and examined the durability of spontaneous control of HCV in the setting of HIV-1 infection.

Spontaneous control of HCV was strongly associated with T cell proliferative responses, the authors report, but these HCV-specific responses were much less common among patients infected with both HIV and HCV.

Lower nadir CD4+ T cell counts were strongly correlated with weaker HCV-specific CD4+ lymphoproliferative responses, the results indicate, as were responses against HIV p24 antigen.

Six of 25 coinfected participants experienced recurrent HCV viremia, the researchers note, compared with none of 16 HIV-negative HCV controllers.

Moreover, the report indicates, patients with higher CD4+ T cell counts showed lower levels of HCV viremia following recurrence, and the shift from controlled to chronic HCV viremia was associated with attenuation of circulating immune responses.

"Further understanding of the immune correlates of maintaining natural HCV control and subsequent loss of control will enhance our knowledge of the quality and quantity of CF4+ and CD8+ T cell responses necessary to elicit long-lasting and cross-protective immunity," the authors conclude.

"Our further studies will address the more pressing issue of accelerated liver disease progression in HIV-positive individuals with HCV coinfection," Dr. Kim said. "We are examining whether earlier treatment of HIV-1 can affect liver disease outcomes and mortality."

PLoS Medicine 2006;12:e492.