Plasma Bioavailable Interleukin‐6 Is Elevated in Human Immunodeficiency Virus–Infected Patients Who Experience Herpesvirus‐Associated Immune Restoration Disease after Start of Highly Active Antiretroviral Therapy

Abstract

This study compared plasma bioavailable interleukin (IL)-6 levels in 3 groups: human immunodeficiency virus (HIV)-infected patients who had a human herpesvirus (HHV)-associated immune restoration disease (IRD) during highly active antiretroviral therapy (HAART); patients who experienced an IRD initiated by Mycobacterium avium complex, hepatitis C virus, or human papillomavirus; and control patients who had uneventful immune reconstitution. Total IL-6, soluble IL-6 receptor (sIL-6R), and soluble gp130 were measured by ELISA, and levels of free IL-6 and sIL-6/IL-6R complex were modeled mathematically. Persons who had an HHV-associated IRD had increased plasma bioavailable IL-6 before HAART, compared with patients who experienced a non-HHV-associated IRD and with control patients, and their plasma bioavailable IL-6 increased progressively over 3-4 years of treatment. Increased IL-6 production may be a feature of HAART-induced restoration of immune responses to HHV infections and may have long-term immunopathologic consequences.