In recent decades, scientists have advanced our understanding of the body’s response to human immunodeficiency virus (HIV) and hepatitis C virus (HCV). However, the biology of HIV/HCV coinfection – simultaneous infection with both viruses – remains a scientific riddle, presenting serious challenges to the clinical management of the resulting cases. In the October issue of the medical journal Gut, an international group of scientists from Oxford, UK; Los Angeles, CA; and Chapel Hill, NC, presented pioneering research that offers a glimpse of the biology of HIV/HCV coinfection in people with hemophilia.
By comparing a group of 126 HCV-infected subjects with 207 subjects coinfected with both HIV and HCV, the scientists discovered that the coinfected group produced significantly lower levels of a specific type of immune cell--interferon g secreting CD4+ T cells. The cells are released by the liver, and are believed to play a major role in antiviral activity against HCV infection. The differing levels of interferon g secreting CD4+ T cells between the two groups show that HCV is sensitive to HIV infection. It further indicates that the liver’s typical role in handling HCV is impaired when there is HIV coinfection, underscoring the fact that liver disease is a serious complication among HIV/HCV-coinfected people.
While highly active antiretroviral treatment (HAART) can increase the levels of CD4+ T cells in the body, it is beyond the scope of this study to determine whether it is effective in restoring interferon g secreting CD4+ T cells in cases of HIV/HCV coinfection. While many questions remain about the immunology of HIV/HCV coinfection, this study offers an optimistic outlook for the hemophilia community. Better understanding of the mechanisms that decrease the volume of interferon g secreting CD4+ T cells may lead to improved therapies that can ultimately prevent deaths due to liver disease in people coinfected with HIV and HCV.
Source: Harcourt G, Gomperts E, Donfield S, et al. Diminished Frequency of Hepatitis C
Virus Specific Interferon g Secreting CD4+ T Cells in Human Immunodeficiency
Virus/Hepatitis C Virus Coinfected Patients. Gut October 2006; 55: 1484-7.