Absence of favourable changes in circulating levels of interleukin-16 or β-chemokine concentration following structured intermittent interruption treatment of chronic human immunodeficiency virus infection

Changes in virological and immunological parameters were analysed following structured intermittent interruption of highly active anti-retroviral therapy (HAART) of patients with chronic human immunodeficiency virus (HIV) infection. Parameters analysed were serum levels of the CD8+ T-cellderived inhibitory molecules interleukin-16 (IL-16), monocyte inhibitory protein-1β (MIP-1β) and RANTES ('regulated upon activation, normal T-cell expressed and presumably secreted'), and the enhancer of HIV replication, monocyte chemotactic protein-1 (MCP-1). Twenty-five patients with chronic HIV infection were evaluated during three cycles of intermittent interruptions of therapy (8 weeks on/4 weeks off) in comparison with 20 healthy sex-and age-matched controls. At enrolment, HIV-infected patients showed significantly higher serum concentrations of IL-16 and RANTES, and significantly lower concentrations of MCP-1, than did healthy controls. Levels of MIP-1β were similar in both groups. Only the serum levels of IL-16 increased significantly in HIV-infected patients after every treatment interruption. However, differences between the CD4+ or CD8+ T-cell counts/μL, HIV loads and serum concentrations of each cytokine at baseline and at the end of the three cycles of intermittent interruptions of therapy were not significant. It was concluded that structured intermittent interruption of HAART for patients with chronic HIV infection did not modify the immunological parameters, including serum levels of CD8+ T-cell-derived inhibitory molecules, or the virus parameters studied. Thus, the findings do not support the use of this treatment modality for the management of HIV-infected patients.