Effect of exposure to injection drugs or alcohol on antigen-specific immune responses in HIV and hepatitis C virus coinfection

Abstract

Background. Ongoing substance use is a potential confounder for immunological studies on hepatitis C virus (HCV), but there is little in the literature regarding the effects of injection drug use (IDU) or alcohol on HCV-specific immune responses. We wanted to determine whether IDU or alcohol affected immune responses in HCV-infected and human immunodeficiency virus (HIV)/HCV coinfected subjects. Methods. Eight-four subjects with HIV/HCV and 57 with HCV were classified as either injection drug users, drinkers, or nonusers based on questionnaire results. Immune responses were studied with enzyme-linked immunosorbent spot assay for interferon (IFN)-γ, interleukin (IL)-10, and tumor necrosis factor (TNF)-α against HCV proteins Core, NS3, and NS5 and recall antigens. Results. Subjects with HIV/HCV, in aggregate, had significantly lower HCV-specific IFN-γ and TNF-α responses than subjects with HCV. However, HIV/HCV injection drug users had HCV-specific IFN-γ and IL-10 responses that were similar to those of HCV injection drug users and were significantly higher than in nonusers with HIV/HCV Conversely, subjects who drank alcohol had similar immune responses to those who were abstinent, among both subjects with HIV/HCV and subjects with HCV Conclusions. Studies that examine IFN-γ or IL-10 immune responses in HIV/HCV-coinfected or HCV-infected persons need to consider current IDU. Alcohol, at levels consumed in this cohort, does not appear to have as much of an effect on antigen-specific immune responses. © 2007 by the Infectious Diseases Society of America. All rights reserved.